/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.support.v7.widget;
import android.content.Context;
import android.database.Observable;
import android.graphics.Canvas;
import android.graphics.PointF;
import android.graphics.Rect;
import android.os.Build;
import android.os.Bundle;
import android.os.Parcel;
import android.os.Parcelable;
import android.support.annotation.Nullable;
import android.support.v4.util.ArrayMap;
import android.support.v4.view.MotionEventCompat;
import android.support.v4.view.VelocityTrackerCompat;
import android.support.v4.view.ViewCompat;
import android.support.v4.view.ViewConfigurationCompat;
import android.support.v4.view.accessibility.AccessibilityEventCompat;
import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat;
import android.support.v4.view.accessibility.AccessibilityRecordCompat;
import android.support.v4.widget.EdgeEffectCompat;
import android.support.v4.widget.ScrollerCompat;
import static android.support.v7.widget.AdapterHelper.UpdateOp;
import static android.support.v7.widget.AdapterHelper.Callback;
import android.util.AttributeSet;
import android.util.Log;
import android.util.SparseArray;
import android.util.SparseIntArray;
import android.view.FocusFinder;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityManager;
import android.view.animation.Interpolator;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* A flexible view for providing a limited window into a large data set.
*
* <h3>Glossary of terms:</h3>
*
* <ul>
* <li><em>Adapter:</em> A subclass of {@link Adapter} responsible for providing views
* that represent items in a data set.</li>
* <li><em>Position:</em> The position of a data item within an <em>Adapter</em>.</li>
* <li><em>Index:</em> The index of an attached child view as used in a call to
* {@link ViewGroup#getChildAt}. Contrast with <em>Position.</em></li>
* <li><em>Binding:</em> The process of preparing a child view to display data corresponding
* to a <em>position</em> within the adapter.</li>
* <li><em>Recycle (view):</em> A view previously used to display data for a specific adapter
* position may be placed in a cache for later reuse to display the same type of data again
* later. This can drastically improve performance by skipping initial layout inflation
* or construction.</li>
* <li><em>Scrap (view):</em> A child view that has entered into a temporarily detached
* state during layout. Scrap views may be reused without becoming fully detached
* from the parent RecyclerView, either unmodified if no rebinding is required or modified
* by the adapter if the view was considered <em>dirty</em>.</li>
* <li><em>Dirty (view):</em> A child view that must be rebound by the adapter before
* being displayed.</li>
* </ul>
*
* <h4>Positions in RecyclerView:</h4>
* <p>
* RecyclerView introduces an additional level of abstraction between the {@link Adapter} and
* {@link LayoutManager} to be able to detect data set changes in batches during a layout
* calculation. This saves LayoutManager from tracking adapter changes to calculate animations.
* It also helps with performance because all view bindings happen at the same time and unnecessary
* bindings are avoided.
* <p>
* For this reason, there are two types of <code>position</code> related methods in RecyclerView:
* <ul>
* <li>layout position: Position of an item in the latest layout calculation. This is the
* position from the LayoutManager's perspective.</li>
* <li>adapter position: Position of an item in the adapter. This is the position from
* the Adapter's perspective.</li>
* </ul>
* <p>
* These two positions are the same except the time between dispatching <code>adapter.notify*
* </code> events and calculating the updated layout.
* <p>
* Methods that return or receive <code>*LayoutPosition*</code> use position as of the latest
* layout calculation (e.g. {@link ViewHolder#getLayoutPosition()},
* {@link #findViewHolderForLayoutPosition(int)}). These positions include all changes until the
* last layout calculation. You can rely on these positions to be consistent with what user is
* currently seeing on the screen. For example, if you have a list of items on the screen and user
* asks for the 5<sup>th</sup> element, you should use these methods as they'll match what user
* is seeing.
* <p>
* The other set of position related methods are in the form of
* <code>*AdapterPosition*</code>. (e.g. {@link ViewHolder#getAdapterPosition()},
* {@link #findViewHolderForAdapterPosition(int)}) You should use these methods when you need to
* work with up-to-date adapter positions even if they may not have been reflected to layout yet.
* For example, if you want to access the item in the adapter on a ViewHolder click, you should use
* {@link ViewHolder#getAdapterPosition()}. Beware that these methods may not be able to calculate
* adapter positions if {@link Adapter#notifyDataSetChanged()} has been called and new layout has
* not yet been calculated. For this reasons, you should carefully handle {@link #NO_POSITION} or
* <code>null</code> results from these methods.
* <p>
* When writing a {@link LayoutManager} you almost always want to use layout positions whereas when
* writing an {@link Adapter}, you probably want to use adapter positions.
*/
public class RecyclerView extends ViewGroup {
private static final String TAG = "RecyclerView";
private static final boolean DEBUG = false;
/**
* On Kitkat, there is a bug which prevents DisplayList from being invalidated if a View is two
* levels deep(wrt to ViewHolder.itemView). DisplayList can be invalidated by setting
* View's visibility to INVISIBLE when View is detached. On Kitkat, Recycler recursively
* traverses itemView and invalidates display list for each ViewGroup that matches this
* criteria.
*/
private static final boolean FORCE_INVALIDATE_DISPLAY_LIST = Build.VERSION.SDK_INT == 19 ||
Build.VERSION.SDK_INT == 20;
private static final boolean DISPATCH_TEMP_DETACH = false;
public static final int HORIZONTAL = 0;
public static final int VERTICAL = 1;
public static final int NO_POSITION = -1;
public static final long NO_ID = -1;
public static final int INVALID_TYPE = -1;
/**
* Constant for use with {@link #setScrollingTouchSlop(int)}. Indicates
* that the RecyclerView should use the standard touch slop for smooth,
* continuous scrolling.
*/
public static final int TOUCH_SLOP_DEFAULT = 0;
/**
* Constant for use with {@link #setScrollingTouchSlop(int)}. Indicates
* that the RecyclerView should use the standard touch slop for scrolling
* widgets that snap to a page or other coarse-grained barrier.
*/
public static final int TOUCH_SLOP_PAGING = 1;
private static final int MAX_SCROLL_DURATION = 2000;
private final RecyclerViewDataObserver mObserver = new RecyclerViewDataObserver();
final Recycler mRecycler = new Recycler();
private SavedState mPendingSavedState;
AdapterHelper mAdapterHelper;
ChildHelper mChildHelper;
// we use this like a set
final List<View> mDisappearingViewsInLayoutPass = new ArrayList<View>();
/**
* Prior to L, there is no way to query this variable which is why we override the setter and
* track it here.
*/
private boolean mClipToPadding;
/**
* Note: this Runnable is only ever posted if:
* 1) We've been through first layout
* 2) We know we have a fixed size (mHasFixedSize)
* 3) We're attached
*/
private final Runnable mUpdateChildViewsRunnable = new Runnable() {
public void run() {
if (!mFirstLayoutComplete) {
// a layout request will happen, we should not do layout here.
return;
}
if (mDataSetHasChangedAfterLayout) {
dispatchLayout();
} else if (mAdapterHelper.hasPendingUpdates()) {
eatRequestLayout();
mAdapterHelper.preProcess();
if (!mLayoutRequestEaten) {
// We run this after pre-processing is complete so that ViewHolders have their
// final adapter positions. No need to run it if a layout is already requested.
rebindUpdatedViewHolders();
}
resumeRequestLayout(true);
}
}
};
private final Rect mTempRect = new Rect();
private Adapter mAdapter;
private LayoutManager mLayout;
private RecyclerListener mRecyclerListener;
private final ArrayList<ItemDecoration> mItemDecorations = new ArrayList<ItemDecoration>();
private final ArrayList<OnItemTouchListener> mOnItemTouchListeners =
new ArrayList<OnItemTouchListener>();
private OnItemTouchListener mActiveOnItemTouchListener;
private boolean mIsAttached;
private boolean mHasFixedSize;
private boolean mFirstLayoutComplete;
private boolean mEatRequestLayout;
private boolean mLayoutRequestEaten;
private boolean mAdapterUpdateDuringMeasure;
private final boolean mPostUpdatesOnAnimation;
private final AccessibilityManager mAccessibilityManager;
/**
* Set to true when an adapter data set changed notification is received.
* In that case, we cannot run any animations since we don't know what happened.
*/
private boolean mDataSetHasChangedAfterLayout = false;
/**
* This variable is set to true during a dispatchLayout and/or scroll.
* Some methods should not be called during these periods (e.g. adapter data change).
* Doing so will create hard to find bugs so we better check it and throw an exception.
*
* @see #assertInLayoutOrScroll(String)
* @see #assertNotInLayoutOrScroll(String)
*/
private boolean mRunningLayoutOrScroll = false;
private EdgeEffectCompat mLeftGlow, mTopGlow, mRightGlow, mBottomGlow;
ItemAnimator mItemAnimator = new DefaultItemAnimator();
private static final int INVALID_POINTER = -1;
/**
* The RecyclerView is not currently scrolling.
* @see #getScrollState()
*/
public static final int SCROLL_STATE_IDLE = 0;
/**
* The RecyclerView is currently being dragged by outside input such as user touch input.
* @see #getScrollState()
*/
public static final int SCROLL_STATE_DRAGGING = 1;
/**
* The RecyclerView is currently animating to a final position while not under
* outside control.
* @see #getScrollState()
*/
public static final int SCROLL_STATE_SETTLING = 2;
// Touch/scrolling handling
private int mScrollState = SCROLL_STATE_IDLE;
private int mScrollPointerId = INVALID_POINTER;
private VelocityTracker mVelocityTracker;
private int mInitialTouchX;
private int mInitialTouchY;
private int mLastTouchX;
private int mLastTouchY;
private int mTouchSlop;
private final int mMinFlingVelocity;
private final int mMaxFlingVelocity;
private final ViewFlinger mViewFlinger = new ViewFlinger();
final State mState = new State();
private OnScrollListener mScrollListener;
// For use in item animations
boolean mItemsAddedOrRemoved = false;
boolean mItemsChanged = false;
private ItemAnimator.ItemAnimatorListener mItemAnimatorListener =
new ItemAnimatorRestoreListener();
private boolean mPostedAnimatorRunner = false;
private RecyclerViewAccessibilityDelegate mAccessibilityDelegate;
// simple array to keep min and max child position during a layout calculation
// preserved not to create a new one in each layout pass
private final int[] mMinMaxLayoutPositions = new int[2];
private Runnable mItemAnimatorRunner = new Runnable() {
@Override
public void run() {
if (mItemAnimator != null) {
mItemAnimator.runPendingAnimations();
}
mPostedAnimatorRunner = false;
}
};
private static final Interpolator sQuinticInterpolator = new Interpolator() {
public float getInterpolation(float t) {
t -= 1.0f;
return t * t * t * t * t + 1.0f;
}
};
public RecyclerView(Context context) {
this(context, null);
}
public RecyclerView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public RecyclerView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
final int version = Build.VERSION.SDK_INT;
mPostUpdatesOnAnimation = version >= 16;
final ViewConfiguration vc = ViewConfiguration.get(context);
mTouchSlop = vc.getScaledTouchSlop();
mMinFlingVelocity = vc.getScaledMinimumFlingVelocity();
mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
setWillNotDraw(ViewCompat.getOverScrollMode(this) == ViewCompat.OVER_SCROLL_NEVER);
mItemAnimator.setListener(mItemAnimatorListener);
initAdapterManager();
initChildrenHelper();
// If not explicitly specified this view is important for accessibility.
if (ViewCompat.getImportantForAccessibility(this)
== ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_AUTO) {
ViewCompat.setImportantForAccessibility(this,
ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_YES);
}
mAccessibilityManager = (AccessibilityManager) getContext()
.getSystemService(Context.ACCESSIBILITY_SERVICE);
setAccessibilityDelegateCompat(new RecyclerViewAccessibilityDelegate(this));
}
/**
* Returns the accessibility delegate compatibility implementation used by the RecyclerView.
* @return An instance of AccessibilityDelegateCompat used by RecyclerView
*/
public RecyclerViewAccessibilityDelegate getCompatAccessibilityDelegate() {
return mAccessibilityDelegate;
}
/**
* Sets the accessibility delegate compatibility implementation used by RecyclerView.
* @param accessibilityDelegate The accessibility delegate to be used by RecyclerView.
*/
public void setAccessibilityDelegateCompat(
RecyclerViewAccessibilityDelegate accessibilityDelegate) {
mAccessibilityDelegate = accessibilityDelegate;
ViewCompat.setAccessibilityDelegate(this, mAccessibilityDelegate);
}
private void initChildrenHelper() {
mChildHelper = new ChildHelper(new ChildHelper.Callback() {
@Override
public int getChildCount() {
return RecyclerView.this.getChildCount();
}
@Override
public void addView(View child, int index) {
RecyclerView.this.addView(child, index);
dispatchChildAttached(child);
}
@Override
public int indexOfChild(View view) {
return RecyclerView.this.indexOfChild(view);
}
@Override
public void removeViewAt(int index) {
final View child = RecyclerView.this.getChildAt(index);
if (child != null) {
dispatchChildDetached(child);
}
RecyclerView.this.removeViewAt(index);
}
@Override
public View getChildAt(int offset) {
return RecyclerView.this.getChildAt(offset);
}
@Override
public void removeAllViews() {
final int count = getChildCount();
for (int i = 0; i < count; i ++) {
dispatchChildDetached(getChildAt(i));
}
RecyclerView.this.removeAllViews();
}
@Override
public ViewHolder getChildViewHolder(View view) {
return getChildViewHolderInt(view);
}
@Override
public void attachViewToParent(View child, int index,
ViewGroup.LayoutParams layoutParams) {
final ViewHolder vh = getChildViewHolderInt(child);
if (vh != null) {
if (!vh.isTmpDetached() && !vh.shouldIgnore()) {
throw new IllegalArgumentException("Called attach on a child which is not"
+ " detached: " + vh);
}
if (DEBUG) {
Log.d(TAG, "reAttach " + vh);
}
vh.clearTmpDetachFlag();
}
RecyclerView.this.attachViewToParent(child, index, layoutParams);
}
@Override
public void detachViewFromParent(int offset) {
final View view = getChildAt(offset);
if (view != null) {
final ViewHolder vh = getChildViewHolderInt(view);
if (vh != null) {
if (vh.isTmpDetached() && !vh.shouldIgnore()) {
throw new IllegalArgumentException("called detach on an already"
+ " detached child " + vh);
}
if (DEBUG) {
Log.d(TAG, "tmpDetach " + vh);
}
vh.addFlags(ViewHolder.FLAG_TMP_DETACHED);
}
}
RecyclerView.this.detachViewFromParent(offset);
}
});
}
void initAdapterManager() {
mAdapterHelper = new AdapterHelper(new Callback() {
@Override
public ViewHolder findViewHolder(int position) {
return findViewHolderForPosition(position, true);
}
@Override
public void offsetPositionsForRemovingInvisible(int start, int count) {
offsetPositionRecordsForRemove(start, count, true);
mItemsAddedOrRemoved = true;
mState.mDeletedInvisibleItemCountSincePreviousLayout += count;
}
@Override
public void offsetPositionsForRemovingLaidOutOrNewView(int positionStart, int itemCount) {
offsetPositionRecordsForRemove(positionStart, itemCount, false);
mItemsAddedOrRemoved = true;
}
@Override
public void markViewHoldersUpdated(int positionStart, int itemCount) {
viewRangeUpdate(positionStart, itemCount);
mItemsChanged = true;
}
@Override
public void onDispatchFirstPass(UpdateOp op) {
dispatchUpdate(op);
}
void dispatchUpdate(UpdateOp op) {
switch (op.cmd) {
case UpdateOp.ADD:
mLayout.onItemsAdded(RecyclerView.this, op.positionStart, op.itemCount);
break;
case UpdateOp.REMOVE:
mLayout.onItemsRemoved(RecyclerView.this, op.positionStart, op.itemCount);
break;
case UpdateOp.UPDATE:
mLayout.onItemsUpdated(RecyclerView.this, op.positionStart, op.itemCount);
break;
case UpdateOp.MOVE:
mLayout.onItemsMoved(RecyclerView.this, op.positionStart, op.itemCount, 1);
break;
}
}
@Override
public void onDispatchSecondPass(UpdateOp op) {
dispatchUpdate(op);
}
@Override
public void offsetPositionsForAdd(int positionStart, int itemCount) {
offsetPositionRecordsForInsert(positionStart, itemCount);
mItemsAddedOrRemoved = true;
}
@Override
public void offsetPositionsForMove(int from, int to) {
offsetPositionRecordsForMove(from, to);
// should we create mItemsMoved ?
mItemsAddedOrRemoved = true;
}
});
}
/**
* RecyclerView can perform several optimizations if it can know in advance that changes in
* adapter content cannot change the size of the RecyclerView itself.
* If your use of RecyclerView falls into this category, set this to true.
*
* @param hasFixedSize true if adapter changes cannot affect the size of the RecyclerView.
*/
public void setHasFixedSize(boolean hasFixedSize) {
mHasFixedSize = hasFixedSize;
}
/**
* @return true if the app has specified that changes in adapter content cannot change
* the size of the RecyclerView itself.
*/
public boolean hasFixedSize() {
return mHasFixedSize;
}
@Override
public void setClipToPadding(boolean clipToPadding) {
if (clipToPadding != mClipToPadding) {
invalidateGlows();
}
mClipToPadding = clipToPadding;
super.setClipToPadding(clipToPadding);
if (mFirstLayoutComplete) {
requestLayout();
}
}
/**
* Configure the scrolling touch slop for a specific use case.
*
* Set up the RecyclerView's scrolling motion threshold based on common usages.
* Valid arguments are {@link #TOUCH_SLOP_DEFAULT} and {@link #TOUCH_SLOP_PAGING}.
*
* @param slopConstant One of the <code>TOUCH_SLOP_</code> constants representing
* the intended usage of this RecyclerView
*/
public void setScrollingTouchSlop(int slopConstant) {
final ViewConfiguration vc = ViewConfiguration.get(getContext());
switch (slopConstant) {
default:
Log.w(TAG, "setScrollingTouchSlop(): bad argument constant "
+ slopConstant + "; using default value");
// fall-through
case TOUCH_SLOP_DEFAULT:
mTouchSlop = vc.getScaledTouchSlop();
break;
case TOUCH_SLOP_PAGING:
mTouchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(vc);
break;
}
}
/**
* Swaps the current adapter with the provided one. It is similar to
* {@link #setAdapter(Adapter)} but assumes existing adapter and the new adapter uses the same
* {@link ViewHolder} and does not clear the RecycledViewPool.
* <p>
* Note that it still calls onAdapterChanged callbacks.
*
* @param adapter The new adapter to set, or null to set no adapter.
* @param removeAndRecycleExistingViews If set to true, RecyclerView will recycle all existing
* Views. If adapters have stable ids and/or you want to
* animate the disappearing views, you may prefer to set
* this to false.
* @see #setAdapter(Adapter)
*/
public void swapAdapter(Adapter adapter, boolean removeAndRecycleExistingViews) {
setAdapterInternal(adapter, true, removeAndRecycleExistingViews);
setDataSetChangedAfterLayout();
requestLayout();
}
/**
* Set a new adapter to provide child views on demand.
* <p>
* When adapter is changed, all existing views are recycled back to the pool. If the pool has
* only one adapter, it will be cleared.
*
* @param adapter The new adapter to set, or null to set no adapter.
* @see #swapAdapter(Adapter, boolean)
*/
public void setAdapter(Adapter adapter) {
setAdapterInternal(adapter, false, true);
requestLayout();
}
/**
* Replaces the current adapter with the new one and triggers listeners.
* @param adapter The new adapter
* @param compatibleWithPrevious If true, the new adapter is using the same View Holders and
* item types with the current adapter (helps us avoid cache
* invalidation).
* @param removeAndRecycleViews If true, we'll remove and recycle all existing views. If
* compatibleWithPrevious is false, this parameter is ignored.
*/
private void setAdapterInternal(Adapter adapter, boolean compatibleWithPrevious,
boolean removeAndRecycleViews) {
if (mAdapter != null) {
mAdapter.unregisterAdapterDataObserver(mObserver);
mAdapter.onDetachedFromRecyclerView(this);
}
if (!compatibleWithPrevious || removeAndRecycleViews) {
// end all running animations
if (mItemAnimator != null) {
mItemAnimator.endAnimations();
}
// Since animations are ended, mLayout.children should be equal to
// recyclerView.children. This may not be true if item animator's end does not work as
// expected. (e.g. not release children instantly). It is safer to use mLayout's child
// count.
if (mLayout != null) {
mLayout.removeAndRecycleAllViews(mRecycler);
mLayout.removeAndRecycleScrapInt(mRecycler);
}
// we should clear it here before adapters are swapped to ensure correct callbacks.
mRecycler.clear();
}
mAdapterHelper.reset();
final Adapter oldAdapter = mAdapter;
mAdapter = adapter;
if (adapter != null) {
adapter.registerAdapterDataObserver(mObserver);
adapter.onAttachedToRecyclerView(this);
}
if (mLayout != null) {
mLayout.onAdapterChanged(oldAdapter, mAdapter);
}
mRecycler.onAdapterChanged(oldAdapter, mAdapter, compatibleWithPrevious);
mState.mStructureChanged = true;
markKnownViewsInvalid();
}
/**
* Retrieves the previously set adapter or null if no adapter is set.
*
* @return The previously set adapter
* @see #setAdapter(Adapter)
*/
public Adapter getAdapter() {
return mAdapter;
}
/**
* Register a listener that will be notified whenever a child view is recycled.
*
* <p>This listener will be called when a LayoutManager or the RecyclerView decides
* that a child view is no longer needed. If an application associates expensive
* or heavyweight data with item views, this may be a good place to release
* or free those resources.</p>
*
* @param listener Listener to register, or null to clear
*/
public void setRecyclerListener(RecyclerListener listener) {
mRecyclerListener = listener;
}
/**
* Set the {@link LayoutManager} that this RecyclerView will use.
*
* <p>In contrast to other adapter-backed views such as {@link android.widget.ListView}
* or {@link android.widget.GridView}, RecyclerView allows client code to provide custom
* layout arrangements for child views. These arrangements are controlled by the
* {@link LayoutManager}. A LayoutManager must be provided for RecyclerView to function.</p>
*
* <p>Several default strategies are provided for common uses such as lists and grids.</p>
*
* @param layout LayoutManager to use
*/
public void setLayoutManager(LayoutManager layout) {
if (layout == mLayout) {
return;
}
// TODO We should do this switch a dispachLayout pass and animate children. There is a good
// chance that LayoutManagers will re-use views.
if (mLayout != null) {
if (mIsAttached) {
mLayout.onDetachedFromWindow(this, mRecycler);
}
mLayout.setRecyclerView(null);
}
mRecycler.clear();
mChildHelper.removeAllViewsUnfiltered();
mLayout = layout;
if (layout != null) {
if (layout.mRecyclerView != null) {
throw new IllegalArgumentException("LayoutManager " + layout +
" is already attached to a RecyclerView: " + layout.mRecyclerView);
}
mLayout.setRecyclerView(this);
if (mIsAttached) {
mLayout.onAttachedToWindow(this);
}
}
requestLayout();
}
@Override
protected Parcelable onSaveInstanceState() {
SavedState state = new SavedState(super.onSaveInstanceState());
if (mPendingSavedState != null) {
state.copyFrom(mPendingSavedState);
} else if (mLayout != null) {
state.mLayoutState = mLayout.onSaveInstanceState();
} else {
state.mLayoutState = null;
}
return state;
}
@Override
protected void onRestoreInstanceState(Parcelable state) {
mPendingSavedState = (SavedState) state;
super.onRestoreInstanceState(mPendingSavedState.getSuperState());
if (mLayout != null && mPendingSavedState.mLayoutState != null) {
mLayout.onRestoreInstanceState(mPendingSavedState.mLayoutState);
}
}
/**
* Adds a view to the animatingViews list.
* mAnimatingViews holds the child views that are currently being kept around
* purely for the purpose of being animated out of view. They are drawn as a regular
* part of the child list of the RecyclerView, but they are invisible to the LayoutManager
* as they are managed separately from the regular child views.
* @param viewHolder The ViewHolder to be removed
*/
private void addAnimatingView(ViewHolder viewHolder) {
final View view = viewHolder.itemView;
final boolean alreadyParented = view.getParent() == this;
mRecycler.unscrapView(getChildViewHolder(view));
if (viewHolder.isTmpDetached()) {
// re-attach
mChildHelper.attachViewToParent(view, -1, view.getLayoutParams(), true);
} else if(!alreadyParented) {
mChildHelper.addView(view, true);
} else {
mChildHelper.hide(view);
}
}
/**
* Removes a view from the animatingViews list.
* @param view The view to be removed
* @see #addAnimatingView(RecyclerView.ViewHolder)
* @return true if an animating view is removed
*/
private boolean removeAnimatingView(View view) {
eatRequestLayout();
final boolean removed = mChildHelper.removeViewIfHidden(view);
if (removed) {
final ViewHolder viewHolder = getChildViewHolderInt(view);
mRecycler.unscrapView(viewHolder);
mRecycler.recycleViewHolderInternal(viewHolder);
if (DEBUG) {
Log.d(TAG, "after removing animated view: " + view + ", " + this);
}
}
resumeRequestLayout(false);
return removed;
}
/**
* Return the {@link LayoutManager} currently responsible for
* layout policy for this RecyclerView.
*
* @return The currently bound LayoutManager
*/
public LayoutManager getLayoutManager() {
return mLayout;
}
/**
* Retrieve this RecyclerView's {@link RecycledViewPool}. This method will never return null;
* if no pool is set for this view a new one will be created. See
* {@link #setRecycledViewPool(RecycledViewPool) setRecycledViewPool} for more information.
*
* @return The pool used to store recycled item views for reuse.
* @see #setRecycledViewPool(RecycledViewPool)
*/
public RecycledViewPool getRecycledViewPool() {
return mRecycler.getRecycledViewPool();
}
/**
* Recycled view pools allow multiple RecyclerViews to share a common pool of scrap views.
* This can be useful if you have multiple RecyclerViews with adapters that use the same
* view types, for example if you have several data sets with the same kinds of item views
* displayed by a {@link android.support.v4.view.ViewPager ViewPager}.
*
* @param pool Pool to set. If this parameter is null a new pool will be created and used.
*/
public void setRecycledViewPool(RecycledViewPool pool) {
mRecycler.setRecycledViewPool(pool);
}
/**
* Sets a new {@link ViewCacheExtension} to be used by the Recycler.
*
* @param extension ViewCacheExtension to be used or null if you want to clear the existing one.
*
* @see {@link ViewCacheExtension#getViewForPositionAndType(Recycler, int, int)}
*/
public void setViewCacheExtension(ViewCacheExtension extension) {
mRecycler.setViewCacheExtension(extension);
}
/**
* Set the number of offscreen views to retain before adding them to the potentially shared
* {@link #getRecycledViewPool() recycled view pool}.
*
* <p>The offscreen view cache stays aware of changes in the attached adapter, allowing
* a LayoutManager to reuse those views unmodified without needing to return to the adapter
* to rebind them.</p>
*
* @param size Number of views to cache offscreen before returning them to the general
* recycled view pool
*/
public void setItemViewCacheSize(int size) {
mRecycler.setViewCacheSize(size);
}
/**
* Return the current scrolling state of the RecyclerView.
*
* @return {@link #SCROLL_STATE_IDLE}, {@link #SCROLL_STATE_DRAGGING} or
* {@link #SCROLL_STATE_SETTLING}
*/
public int getScrollState() {
return mScrollState;
}
private void setScrollState(int state) {
if (state == mScrollState) {
return;
}
if (DEBUG) {
Log.d(TAG, "setting scroll state to " + state + " from " + mScrollState, new Exception());
}
mScrollState = state;
if (state != SCROLL_STATE_SETTLING) {
stopScrollersInternal();
}
if (mScrollListener != null) {
mScrollListener.onScrollStateChanged(this, state);
}
if (mLayout != null) {
mLayout.onScrollStateChanged(state);
}
}
/**
* Add an {@link ItemDecoration} to this RecyclerView. Item decorations can
* affect both measurement and drawing of individual item views.
*
* <p>Item decorations are ordered. Decorations placed earlier in the list will
* be run/queried/drawn first for their effects on item views. Padding added to views
* will be nested; a padding added by an earlier decoration will mean further
* item decorations in the list will be asked to draw/pad within the previous decoration's
* given area.</p>
*
* @param decor Decoration to add
* @param index Position in the decoration chain to insert this decoration at. If this value
* is negative the decoration will be added at the end.
*/
public void addItemDecoration(ItemDecoration decor, int index) {
if (mLayout != null) {
mLayout.assertNotInLayoutOrScroll("Cannot add item decoration during a scroll or"
+ " layout");
}
if (mItemDecorations.isEmpty()) {
setWillNotDraw(false);
}
if (index < 0) {
mItemDecorations.add(decor);
} else {
mItemDecorations.add(index, decor);
}
markItemDecorInsetsDirty();
requestLayout();
}
/**
* Add an {@link ItemDecoration} to this RecyclerView. Item decorations can
* affect both measurement and drawing of individual item views.
*
* <p>Item decorations are ordered. Decorations placed earlier in the list will
* be run/queried/drawn first for their effects on item views. Padding added to views
* will be nested; a padding added by an earlier decoration will mean further
* item decorations in the list will be asked to draw/pad within the previous decoration's
* given area.</p>
*
* @param decor Decoration to add
*/
public void addItemDecoration(ItemDecoration decor) {
addItemDecoration(decor, -1);
}
/**
* Remove an {@link ItemDecoration} from this RecyclerView.
*
* <p>The given decoration will no longer impact the measurement and drawing of
* item views.</p>
*
* @param decor Decoration to remove
* @see #addItemDecoration(ItemDecoration)
*/
public void removeItemDecoration(ItemDecoration decor) {
if (mLayout != null) {
mLayout.assertNotInLayoutOrScroll("Cannot remove item decoration during a scroll or"
+ " layout");
}
mItemDecorations.remove(decor);
if (mItemDecorations.isEmpty()) {
setWillNotDraw(ViewCompat.getOverScrollMode(this) == ViewCompat.OVER_SCROLL_NEVER);
}
markItemDecorInsetsDirty();
requestLayout();
}
/**
* Set a listener that will be notified of any changes in scroll state or position.
*
* @param listener Listener to set or null to clear
*/
public void setOnScrollListener(OnScrollListener listener) {
mScrollListener = listener;
}
/**
* Convenience method to scroll to a certain position.
*
* RecyclerView does not implement scrolling logic, rather forwards the call to
* {@link android.support.v7.widget.RecyclerView.LayoutManager#scrollToPosition(int)}
* @param position Scroll to this adapter position
* @see android.support.v7.widget.RecyclerView.LayoutManager#scrollToPosition(int)
*/
public void scrollToPosition(int position) {
stopScroll();
if (mLayout == null) {
Log.e(TAG, "Cannot scroll to position a LayoutManager set. " +
"Call setLayoutManager with a non-null argument.");
return;
}
mLayout.scrollToPosition(position);
awakenScrollBars();
}
/**
* Starts a smooth scroll to an adapter position.
* <p>
* To support smooth scrolling, you must override
* {@link LayoutManager#smoothScrollToPosition(RecyclerView, State, int)} and create a
* {@link SmoothScroller}.
* <p>
* {@link LayoutManager} is responsible for creating the actual scroll action. If you want to
* provide a custom smooth scroll logic, override
* {@link LayoutManager#smoothScrollToPosition(RecyclerView, State, int)} in your
* LayoutManager.
*
* @param position The adapter position to scroll to
* @see LayoutManager#smoothScrollToPosition(RecyclerView, State, int)
*/
public void smoothScrollToPosition(int position) {
if (mLayout == null) {
Log.e(TAG, "Cannot smooth scroll without a LayoutManager set. " +
"Call setLayoutManager with a non-null argument.");
return;
}
mLayout.smoothScrollToPosition(this, mState, position);
}
@Override
public void scrollTo(int x, int y) {
throw new UnsupportedOperationException(
"RecyclerView does not support scrolling to an absolute position.");
}
@Override
public void scrollBy(int x, int y) {
if (mLayout == null) {
Log.e(TAG, "Cannot scroll without a LayoutManager set. " +
"Call setLayoutManager with a non-null argument.");
return;
}
final boolean canScrollHorizontal = mLayout.canScrollHorizontally();
final boolean canScrollVertical = mLayout.canScrollVertically();
if (canScrollHorizontal || canScrollVertical) {
scrollByInternal(canScrollHorizontal ? x : 0, canScrollVertical ? y : 0);
}
}
/**
* Helper method reflect data changes to the state.
* <p>
* Adapter changes during a scroll may trigger a crash because scroll assumes no data change
* but data actually changed.
* <p>
* This method consumes all deferred changes to avoid that case.
*/
private void consumePendingUpdateOperations() {
mUpdateChildViewsRunnable.run();
}
/**
* Does not perform bounds checking. Used by internal methods that have already validated input.
*
* @return Whether any scroll was consumed in either direction.
*/
boolean scrollByInternal(int x, int y) {
int overscrollX = 0, overscrollY = 0;
int hresult = 0, vresult = 0;
consumePendingUpdateOperations();
if (mAdapter != null) {
eatRequestLayout();
mRunningLayoutOrScroll = true;
if (x != 0) {
hresult = mLayout.scrollHorizontallyBy(x, mRecycler, mState);
overscrollX = x - hresult;
}
if (y != 0) {
vresult = mLayout.scrollVerticallyBy(y, mRecycler, mState);
overscrollY = y - vresult;
}
if (supportsChangeAnimations()) {
// Fix up shadow views used by changing animations
int count = mChildHelper.getChildCount();
for (int i = 0; i < count; i++) {
View view = mChildHelper.getChildAt(i);
ViewHolder holder = getChildViewHolder(view);
if (holder != null && holder.mShadowingHolder != null) {
ViewHolder shadowingHolder = holder.mShadowingHolder;
View shadowingView = shadowingHolder != null ? shadowingHolder.itemView : null;
if (shadowingView != null) {
int left = view.getLeft();
int top = view.getTop();
if (left != shadowingView.getLeft() || top != shadowingView.getTop()) {
shadowingView.layout(left, top,
left + shadowingView.getWidth(),
top + shadowingView.getHeight());
}
}
}
}
}
mRunningLayoutOrScroll = false;
resumeRequestLayout(false);
}
if (!mItemDecorations.isEmpty()) {
invalidate();
}
if (ViewCompat.getOverScrollMode(this) != ViewCompat.OVER_SCROLL_NEVER) {
considerReleasingGlowsOnScroll(x, y);
pullGlows(overscrollX, overscrollY);
}
if (hresult != 0 || vresult != 0) {
notifyOnScrolled(hresult, vresult);
}
if (!awakenScrollBars()) {
invalidate();
}
return hresult != 0 || vresult != 0;
}
/**
* <p>Compute the horizontal offset of the horizontal scrollbar's thumb within the horizontal
* range. This value is used to compute the length of the thumb within the scrollbar's track.
* </p>
*
* <p>The range is expressed in arbitrary units that must be the same as the units used by
* {@link #computeHorizontalScrollRange()} and {@link #computeHorizontalScrollExtent()}.</p>
*
* <p>Default implementation returns 0.</p>
*
* <p>If you want to support scroll bars, override
* {@link RecyclerView.LayoutManager#computeHorizontalScrollOffset(RecyclerView.State)} in your
* LayoutManager. </p>
*
* @return The horizontal offset of the scrollbar's thumb
* @see android.support.v7.widget.RecyclerView.LayoutManager#computeHorizontalScrollOffset
* (RecyclerView.Adapter)
*/
@Override
protected int computeHorizontalScrollOffset() {
return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollOffset(mState)
: 0;
}
/**
* <p>Compute the horizontal extent of the horizontal scrollbar's thumb within the
* horizontal range. This value is used to compute the length of the thumb within the
* scrollbar's track.</p>
*
* <p>The range is expressed in arbitrary units that must be the same as the units used by
* {@link #computeHorizontalScrollRange()} and {@link #computeHorizontalScrollOffset()}.</p>
*
* <p>Default implementation returns 0.</p>
*
* <p>If you want to support scroll bars, override
* {@link RecyclerView.LayoutManager#computeHorizontalScrollExtent(RecyclerView.State)} in your
* LayoutManager.</p>
*
* @return The horizontal extent of the scrollbar's thumb
* @see RecyclerView.LayoutManager#computeHorizontalScrollExtent(RecyclerView.State)
*/
@Override
protected int computeHorizontalScrollExtent() {
return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollExtent(mState) : 0;
}
/**
* <p>Compute the horizontal range that the horizontal scrollbar represents.</p>
*
* <p>The range is expressed in arbitrary units that must be the same as the units used by
* {@link #computeHorizontalScrollExtent()} and {@link #computeHorizontalScrollOffset()}.</p>
*
* <p>Default implementation returns 0.</p>
*
* <p>If you want to support scroll bars, override
* {@link RecyclerView.LayoutManager#computeHorizontalScrollRange(RecyclerView.State)} in your
* LayoutManager.</p>
*
* @return The total horizontal range represented by the vertical scrollbar
* @see RecyclerView.LayoutManager#computeHorizontalScrollRange(RecyclerView.State)
*/
@Override
protected int computeHorizontalScrollRange() {
return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollRange(mState) : 0;
}
/**
* <p>Compute the vertical offset of the vertical scrollbar's thumb within the vertical range.
* This value is used to compute the length of the thumb within the scrollbar's track. </p>
*
* <p>The range is expressed in arbitrary units that must be the same as the units used by
* {@link #computeVerticalScrollRange()} and {@link #computeVerticalScrollExtent()}.</p>
*
* <p>Default implementation returns 0.</p>
*
* <p>If you want to support scroll bars, override
* {@link RecyclerView.LayoutManager#computeVerticalScrollOffset(RecyclerView.State)} in your
* LayoutManager.</p>
*
* @return The vertical offset of the scrollbar's thumb
* @see android.support.v7.widget.RecyclerView.LayoutManager#computeVerticalScrollOffset
* (RecyclerView.Adapter)
*/
@Override
protected int computeVerticalScrollOffset() {
return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollOffset(mState) : 0;
}
/**
* <p>Compute the vertical extent of the vertical scrollbar's thumb within the vertical range.
* This value is used to compute the length of the thumb within the scrollbar's track.</p>
*
* <p>The range is expressed in arbitrary units that must be the same as the units used by
* {@link #computeVerticalScrollRange()} and {@link #computeVerticalScrollOffset()}.</p>
*
* <p>Default implementation returns 0.</p>
*
* <p>If you want to support scroll bars, override
* {@link RecyclerView.LayoutManager#computeVerticalScrollExtent(RecyclerView.State)} in your
* LayoutManager.</p>
*
* @return The vertical extent of the scrollbar's thumb
* @see RecyclerView.LayoutManager#computeVerticalScrollExtent(RecyclerView.State)
*/
@Override
protected int computeVerticalScrollExtent() {
return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollExtent(mState) : 0;
}
/**
* <p>Compute the vertical range that the vertical scrollbar represents.</p>
*
* <p>The range is expressed in arbitrary units that must be the same as the units used by
* {@link #computeVerticalScrollExtent()} and {@link #computeVerticalScrollOffset()}.</p>
*
* <p>Default implementation returns 0.</p>
*
* <p>If you want to support scroll bars, override
* {@link RecyclerView.LayoutManager#computeVerticalScrollRange(RecyclerView.State)} in your
* LayoutManager.</p>
*
* @return The total vertical range represented by the vertical scrollbar
* @see RecyclerView.LayoutManager#computeVerticalScrollRange(RecyclerView.State)
*/
@Override
protected int computeVerticalScrollRange() {
return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollRange(mState) : 0;
}
void eatRequestLayout() {
if (!mEatRequestLayout) {
mEatRequestLayout = true;
mLayoutRequestEaten = false;
}
}
void resumeRequestLayout(boolean performLayoutChildren) {
if (mEatRequestLayout) {
if (performLayoutChildren && mLayoutRequestEaten &&
mLayout != null && mAdapter != null) {
dispatchLayout();
}
mEatRequestLayout = false;
mLayoutRequestEaten = false;
}
}
/**
* Animate a scroll by the given amount of pixels along either axis.
*
* @param dx Pixels to scroll horizontally
* @param dy Pixels to scroll vertically
*/
public void smoothScrollBy(int dx, int dy) {
if (mLayout == null) {
Log.e(TAG, "Cannot smooth scroll without a LayoutManager set. " +
"Call setLayoutManager with a non-null argument.");
return;
}
if (!mLayout.canScrollHorizontally()) {
dx = 0;
}
if (!mLayout.canScrollVertically()) {
dy = 0;
}
if (dx != 0 || dy != 0) {
mViewFlinger.smoothScrollBy(dx, dy);
}
}
/**
* Begin a standard fling with an initial velocity along each axis in pixels per second.
* If the velocity given is below the system-defined minimum this method will return false
* and no fling will occur.
*
* @param velocityX Initial horizontal velocity in pixels per second
* @param velocityY Initial vertical velocity in pixels per second
* @return true if the fling was started, false if the velocity was too low to fling or
* LayoutManager does not support scrolling in the axis fling is issued.
*
* @see LayoutManager#canScrollVertically()
* @see LayoutManager#canScrollHorizontally()
*/
public boolean fling(int velocityX, int velocityY) {
if (mLayout == null) {
Log.e(TAG, "Cannot fling without a LayoutManager set. " +
"Call setLayoutManager with a non-null argument.");
return false;
}
final boolean canScrollHorizontal = mLayout.canScrollHorizontally();
final boolean canScrollVertical = mLayout.canScrollVertically();
if (!canScrollHorizontal || Math.abs(velocityX) < mMinFlingVelocity) {
velocityX = 0;
}
if (!canScrollVertical || Math.abs(velocityY) < mMinFlingVelocity) {
velocityY = 0;
}
velocityX = Math.max(-mMaxFlingVelocity, Math.min(velocityX, mMaxFlingVelocity));
velocityY = Math.max(-mMaxFlingVelocity, Math.min(velocityY, mMaxFlingVelocity));
if (velocityX != 0 || velocityY != 0) {
mViewFlinger.fling(velocityX, velocityY);
return true;
}
return false;
}
/**
* Stop any current scroll in progress, such as one started by
* {@link #smoothScrollBy(int, int)}, {@link #fling(int, int)} or a touch-initiated fling.
*/
public void stopScroll() {
setScrollState(SCROLL_STATE_IDLE);
stopScrollersInternal();
}
/**
* Similar to {@link #stopScroll()} but does not set the state.
*/
private void stopScrollersInternal() {
mViewFlinger.stop();
if (mLayout != null) {
mLayout.stopSmoothScroller();
}
}
/**
* Apply a pull to relevant overscroll glow effects
*/
private void pullGlows(int overscrollX, int overscrollY) {
if (overscrollX < 0) {
ensureLeftGlow();
mLeftGlow.onPull(-overscrollX / (float) getWidth());
} else if (overscrollX > 0) {
ensureRightGlow();
mRightGlow.onPull(overscrollX / (float) getWidth());
}
if (overscrollY < 0) {
ensureTopGlow();
mTopGlow.onPull(-overscrollY / (float) getHeight());
} else if (overscrollY > 0) {
ensureBottomGlow();
mBottomGlow.onPull(overscrollY / (float) getHeight());
}
if (overscrollX != 0 || overscrollY != 0) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
private void releaseGlows() {
boolean needsInvalidate = false;
if (mLeftGlow != null) needsInvalidate = mLeftGlow.onRelease();
if (mTopGlow != null) needsInvalidate |= mTopGlow.onRelease();
if (mRightGlow != null) needsInvalidate |= mRightGlow.onRelease();
if (mBottomGlow != null) needsInvalidate |= mBottomGlow.onRelease();
if (needsInvalidate) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
private void considerReleasingGlowsOnScroll(int dx, int dy) {
boolean needsInvalidate = false;
if (mLeftGlow != null && !mLeftGlow.isFinished() && dx > 0) {
needsInvalidate = mLeftGlow.onRelease();
}
if (mRightGlow != null && !mRightGlow.isFinished() && dx < 0) {
needsInvalidate |= mRightGlow.onRelease();
}
if (mTopGlow != null && !mTopGlow.isFinished() && dy > 0) {
needsInvalidate |= mTopGlow.onRelease();
}
if (mBottomGlow != null && !mBottomGlow.isFinished() && dy < 0) {
needsInvalidate |= mBottomGlow.onRelease();
}
if (needsInvalidate) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
void absorbGlows(int velocityX, int velocityY) {
if (velocityX < 0) {
ensureLeftGlow();
mLeftGlow.onAbsorb(-velocityX);
} else if (velocityX > 0) {
ensureRightGlow();
mRightGlow.onAbsorb(velocityX);
}
if (velocityY < 0) {
ensureTopGlow();
mTopGlow.onAbsorb(-velocityY);
} else if (velocityY > 0) {
ensureBottomGlow();
mBottomGlow.onAbsorb(velocityY);
}
if (velocityX != 0 || velocityY != 0) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
void ensureLeftGlow() {
if (mLeftGlow != null) {
return;
}
mLeftGlow = new EdgeEffectCompat(getContext());
if (mClipToPadding) {
mLeftGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(),
getMeasuredWidth() - getPaddingLeft() - getPaddingRight());
} else {
mLeftGlow.setSize(getMeasuredHeight(), getMeasuredWidth());
}
}
void ensureRightGlow() {
if (mRightGlow != null) {
return;
}
mRightGlow = new EdgeEffectCompat(getContext());
if (mClipToPadding) {
mRightGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(),
getMeasuredWidth() - getPaddingLeft() - getPaddingRight());
} else {
mRightGlow.setSize(getMeasuredHeight(), getMeasuredWidth());
}
}
void ensureTopGlow() {
if (mTopGlow != null) {
return;
}
mTopGlow = new EdgeEffectCompat(getContext());
if (mClipToPadding) {
mTopGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(),
getMeasuredHeight() - getPaddingTop() - getPaddingBottom());
} else {
mTopGlow.setSize(getMeasuredWidth(), getMeasuredHeight());
}
}
void ensureBottomGlow() {
if (mBottomGlow != null) {
return;
}
mBottomGlow = new EdgeEffectCompat(getContext());
if (mClipToPadding) {
mBottomGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(),
getMeasuredHeight() - getPaddingTop() - getPaddingBottom());
} else {
mBottomGlow.setSize(getMeasuredWidth(), getMeasuredHeight());
}
}
void invalidateGlows() {
mLeftGlow = mRightGlow = mTopGlow = mBottomGlow = null;
}
// Focus handling
@Override
public View focusSearch(View focused, int direction) {
View result = mLayout.onInterceptFocusSearch(focused, direction);
if (result != null) {
return result;
}
final FocusFinder ff = FocusFinder.getInstance();
result = ff.findNextFocus(this, focused, direction);
if (result == null && mAdapter != null && mLayout != null) {
eatRequestLayout();
result = mLayout.onFocusSearchFailed(focused, direction, mRecycler, mState);
resumeRequestLayout(false);
}
return result != null ? result : super.focusSearch(focused, direction);
}
@Override
public void requestChildFocus(View child, View focused) {
if (!mLayout.onRequestChildFocus(this, mState, child, focused) && focused != null) {
mTempRect.set(0, 0, focused.getWidth(), focused.getHeight());
offsetDescendantRectToMyCoords(focused, mTempRect);
offsetRectIntoDescendantCoords(child, mTempRect);
requestChildRectangleOnScreen(child, mTempRect, !mFirstLayoutComplete);
}
super.requestChildFocus(child, focused);
}
@Override
public boolean requestChildRectangleOnScreen(View child, Rect rect, boolean immediate) {
return mLayout.requestChildRectangleOnScreen(this, child, rect, immediate);
}
@Override
public void addFocusables(ArrayList<View> views, int direction, int focusableMode) {
if (!mLayout.onAddFocusables(this, views, direction, focusableMode)) {
super.addFocusables(views, direction, focusableMode);
}
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
mIsAttached = true;
mFirstLayoutComplete = false;
if (mLayout != null) {
mLayout.onAttachedToWindow(this);
}
mPostedAnimatorRunner = false;
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
if (mItemAnimator != null) {
mItemAnimator.endAnimations();
}
mFirstLayoutComplete = false;
stopScroll();
mIsAttached = false;
if (mLayout != null) {
mLayout.onDetachedFromWindow(this, mRecycler);
}
removeCallbacks(mItemAnimatorRunner);
}
/**
* Checks if RecyclerView is in the middle of a layout or scroll and throws an
* {@link IllegalStateException} if it <b>is not</b>.
*
* @param message The message for the exception. Can be null.
* @see #assertNotInLayoutOrScroll(String)
*/
void assertInLayoutOrScroll(String message) {
if (!mRunningLayoutOrScroll) {
if (message == null) {
throw new IllegalStateException("Cannot call this method unless RecyclerView is "
+ "computing a layout or scrolling");
}
throw new IllegalStateException(message);
}
}
/**
* Checks if RecyclerView is in the middle of a layout or scroll and throws an
* {@link IllegalStateException} if it <b>is</b>.
*
* @param message The message for the exception. Can be null.
* @see #assertInLayoutOrScroll(String)
*/
void assertNotInLayoutOrScroll(String message) {
if (mRunningLayoutOrScroll) {
if (message == null) {
throw new IllegalStateException("Cannot call this method while RecyclerView is "
+ "computing a layout or scrolling");
}
throw new IllegalStateException(message);
}
}
/**
* Add an {@link OnItemTouchListener} to intercept touch events before they are dispatched
* to child views or this view's standard scrolling behavior.
*
* <p>Client code may use listeners to implement item manipulation behavior. Once a listener
* returns true from
* {@link OnItemTouchListener#onInterceptTouchEvent(RecyclerView, MotionEvent)} its
* {@link OnItemTouchListener#onTouchEvent(RecyclerView, MotionEvent)} method will be called
* for each incoming MotionEvent until the end of the gesture.</p>
*
* @param listener Listener to add
*/
public void addOnItemTouchListener(OnItemTouchListener listener) {
mOnItemTouchListeners.add(listener);
}
/**
* Remove an {@link OnItemTouchListener}. It will no longer be able to intercept touch events.
*
* @param listener Listener to remove
*/
public void removeOnItemTouchListener(OnItemTouchListener listener) {
mOnItemTouchListeners.remove(listener);
if (mActiveOnItemTouchListener == listener) {
mActiveOnItemTouchListener = null;
}
}
private boolean dispatchOnItemTouchIntercept(MotionEvent e) {
final int action = e.getAction();
if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_DOWN) {
mActiveOnItemTouchListener = null;
}
final int listenerCount = mOnItemTouchListeners.size();
for (int i = 0; i < listenerCount; i++) {
final OnItemTouchListener listener = mOnItemTouchListeners.get(i);
if (listener.onInterceptTouchEvent(this, e) && action != MotionEvent.ACTION_CANCEL) {
mActiveOnItemTouchListener = listener;
return true;
}
}
return false;
}
private boolean dispatchOnItemTouch(MotionEvent e) {
final int action = e.getAction();
if (mActiveOnItemTouchListener != null) {
if (action == MotionEvent.ACTION_DOWN) {
// Stale state from a previous gesture, we're starting a new one. Clear it.
mActiveOnItemTouchListener = null;
} else {
mActiveOnItemTouchListener.onTouchEvent(this, e);
if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) {
// Clean up for the next gesture.
mActiveOnItemTouchListener = null;
}
return true;
}
}
// Listeners will have already received the ACTION_DOWN via dispatchOnItemTouchIntercept
// as called from onInterceptTouchEvent; skip it.
if (action != MotionEvent.ACTION_DOWN) {
final int listenerCount = mOnItemTouchListeners.size();
for (int i = 0; i < listenerCount; i++) {
final OnItemTouchListener listener = mOnItemTouchListeners.get(i);
if (listener.onInterceptTouchEvent(this, e)) {
mActiveOnItemTouchListener = listener;
return true;
}
}
}
return false;
}
@Override
public boolean onInterceptTouchEvent(MotionEvent e) {
if (dispatchOnItemTouchIntercept(e)) {
cancelTouch();
return true;
}
final boolean canScrollHorizontally = mLayout.canScrollHorizontally();
final boolean canScrollVertically = mLayout.canScrollVertically();
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(e);
final int action = MotionEventCompat.getActionMasked(e);
final int actionIndex = MotionEventCompat.getActionIndex(e);
switch (action) {
case MotionEvent.ACTION_DOWN:
mScrollPointerId = MotionEventCompat.getPointerId(e, 0);
mInitialTouchX = mLastTouchX = (int) (e.getX() + 0.5f);
mInitialTouchY = mLastTouchY = (int) (e.getY() + 0.5f);
if (mScrollState == SCROLL_STATE_SETTLING) {
getParent().requestDisallowInterceptTouchEvent(true);
setScrollState(SCROLL_STATE_DRAGGING);
}
break;
case MotionEventCompat.ACTION_POINTER_DOWN:
mScrollPointerId = MotionEventCompat.getPointerId(e, actionIndex);
mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, actionIndex) + 0.5f);
mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, actionIndex) + 0.5f);
break;
case MotionEvent.ACTION_MOVE: {
final int index = MotionEventCompat.findPointerIndex(e, mScrollPointerId);
if (index < 0) {
Log.e(TAG, "Error processing scroll; pointer index for id " +
mScrollPointerId + " not found. Did any MotionEvents get skipped?");
return false;
}
final int x = (int) (MotionEventCompat.getX(e, index) + 0.5f);
final int y = (int) (MotionEventCompat.getY(e, index) + 0.5f);
if (mScrollState != SCROLL_STATE_DRAGGING) {
final int dx = x - mInitialTouchX;
final int dy = y - mInitialTouchY;
boolean startScroll = false;
if (canScrollHorizontally && Math.abs(dx) > mTouchSlop) {
mLastTouchX = mInitialTouchX + mTouchSlop * (dx < 0 ? -1 : 1);
startScroll = true;
}
if (canScrollVertically && Math.abs(dy) > mTouchSlop) {
mLastTouchY = mInitialTouchY + mTouchSlop * (dy < 0 ? -1 : 1);
startScroll = true;
}
if (startScroll) {
setScrollState(SCROLL_STATE_DRAGGING);
}
}
} break;
case MotionEventCompat.ACTION_POINTER_UP: {
onPointerUp(e);
} break;
case MotionEvent.ACTION_UP: {
mVelocityTracker.clear();
} break;
case MotionEvent.ACTION_CANCEL: {
cancelTouch();
}
}
return mScrollState == SCROLL_STATE_DRAGGING;
}
@Override
public boolean onTouchEvent(MotionEvent e) {
if (dispatchOnItemTouch(e)) {
cancelTouch();
return true;
}
final boolean canScrollHorizontally = mLayout.canScrollHorizontally();
final boolean canScrollVertically = mLayout.canScrollVertically();
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(e);
final int action = MotionEventCompat.getActionMasked(e);
final int actionIndex = MotionEventCompat.getActionIndex(e);
switch (action) {
case MotionEvent.ACTION_DOWN: {
mScrollPointerId = MotionEventCompat.getPointerId(e, 0);
mInitialTouchX = mLastTouchX = (int) (e.getX() + 0.5f);
mInitialTouchY = mLastTouchY = (int) (e.getY() + 0.5f);
} break;
case MotionEventCompat.ACTION_POINTER_DOWN: {
mScrollPointerId = MotionEventCompat.getPointerId(e, actionIndex);
mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, actionIndex) + 0.5f);
mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, actionIndex) + 0.5f);
} break;
case MotionEvent.ACTION_MOVE: {
final int index = MotionEventCompat.findPointerIndex(e, mScrollPointerId);
if (index < 0) {
Log.e(TAG, "Error processing scroll; pointer index for id " +
mScrollPointerId + " not found. Did any MotionEvents get skipped?");
return false;
}
final int x = (int) (MotionEventCompat.getX(e, index) + 0.5f);
final int y = (int) (MotionEventCompat.getY(e, index) + 0.5f);
if (mScrollState != SCROLL_STATE_DRAGGING) {
final int dx = x - mInitialTouchX;
final int dy = y - mInitialTouchY;
boolean startScroll = false;
if (canScrollHorizontally && Math.abs(dx) > mTouchSlop) {
mLastTouchX = mInitialTouchX + mTouchSlop * (dx < 0 ? -1 : 1);
startScroll = true;
}
if (canScrollVertically && Math.abs(dy) > mTouchSlop) {
mLastTouchY = mInitialTouchY + mTouchSlop * (dy < 0 ? -1 : 1);
startScroll = true;
}
if (startScroll) {
setScrollState(SCROLL_STATE_DRAGGING);
}
}
if (mScrollState == SCROLL_STATE_DRAGGING) {
final int dx = x - mLastTouchX;
final int dy = y - mLastTouchY;
if (scrollByInternal(
canScrollHorizontally ? -dx : 0, canScrollVertically ? -dy : 0)) {
getParent().requestDisallowInterceptTouchEvent(true);
}
}
mLastTouchX = x;
mLastTouchY = y;
} break;
case MotionEventCompat.ACTION_POINTER_UP: {
onPointerUp(e);
} break;
case MotionEvent.ACTION_UP: {
mVelocityTracker.computeCurrentVelocity(1000, mMaxFlingVelocity);
final float xvel = canScrollHorizontally ?
-VelocityTrackerCompat.getXVelocity(mVelocityTracker, mScrollPointerId) : 0;
final float yvel = canScrollVertically ?
-VelocityTrackerCompat.getYVelocity(mVelocityTracker, mScrollPointerId) : 0;
if (!((xvel != 0 || yvel != 0) && fling((int) xvel, (int) yvel))) {
setScrollState(SCROLL_STATE_IDLE);
}
mVelocityTracker.clear();
releaseGlows();
} break;
case MotionEvent.ACTION_CANCEL: {
cancelTouch();
} break;
}
return true;
}
private void cancelTouch() {
if (mVelocityTracker != null) {
mVelocityTracker.clear();
}
releaseGlows();
setScrollState(SCROLL_STATE_IDLE);
}
private void onPointerUp(MotionEvent e) {
final int actionIndex = MotionEventCompat.getActionIndex(e);
if (MotionEventCompat.getPointerId(e, actionIndex) == mScrollPointerId) {
// Pick a new pointer to pick up the slack.
final int newIndex = actionIndex == 0 ? 1 : 0;
mScrollPointerId = MotionEventCompat.getPointerId(e, newIndex);
mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, newIndex) + 0.5f);
mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, newIndex) + 0.5f);
}
}
@Override
protected void onMeasure(int widthSpec, int heightSpec) {
if (mAdapterUpdateDuringMeasure) {
eatRequestLayout();
processAdapterUpdatesAndSetAnimationFlags();
if (mState.mRunPredictiveAnimations) {
// TODO: try to provide a better approach.
// When RV decides to run predictive animations, we need to measure in pre-layout
// state so that pre-layout pass results in correct layout.
// On the other hand, this will prevent the layout manager from resizing properly.
mState.mInPreLayout = true;
} else {
// consume remaining updates to provide a consistent state with the layout pass.
mAdapterHelper.consumeUpdatesInOnePass();
mState.mInPreLayout = false;
}
mAdapterUpdateDuringMeasure = false;
resumeRequestLayout(false);
}
if (mAdapter != null) {
mState.mItemCount = mAdapter.getItemCount();
} else {
mState.mItemCount = 0;
}
if (mLayout == null) {
defaultOnMeasure(widthSpec, heightSpec);
} else {
mLayout.onMeasure(mRecycler, mState, widthSpec, heightSpec);
}
mState.mInPreLayout = false; // clear
}
/**
* Used when onMeasure is called before layout manager is set
*/
private void defaultOnMeasure(int widthSpec, int heightSpec) {
final int widthMode = MeasureSpec.getMode(widthSpec);
final int heightMode = MeasureSpec.getMode(heightSpec);
final int widthSize = MeasureSpec.getSize(widthSpec);
final int heightSize = MeasureSpec.getSize(heightSpec);
int width = 0;
int height = 0;
switch (widthMode) {
case MeasureSpec.EXACTLY:
case MeasureSpec.AT_MOST:
width = widthSize;
break;
case MeasureSpec.UNSPECIFIED:
default:
width = ViewCompat.getMinimumWidth(this);
break;
}
switch (heightMode) {
case MeasureSpec.EXACTLY:
case MeasureSpec.AT_MOST:
height = heightSize;
break;
case MeasureSpec.UNSPECIFIED:
default:
height = ViewCompat.getMinimumHeight(this);
break;
}
setMeasuredDimension(width, height);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
if (w != oldw || h != oldh) {
invalidateGlows();
}
}
/**
* Sets the {@link ItemAnimator} that will handle animations involving changes
* to the items in this RecyclerView. By default, RecyclerView instantiates and
* uses an instance of {@link DefaultItemAnimator}. Whether item animations are
* enabled for the RecyclerView depends on the ItemAnimator and whether
* the LayoutManager {@link LayoutManager#supportsPredictiveItemAnimations()
* supports item animations}.
*
* @param animator The ItemAnimator being set. If null, no animations will occur
* when changes occur to the items in this RecyclerView.
*/
public void setItemAnimator(ItemAnimator animator) {
if (mItemAnimator != null) {
mItemAnimator.endAnimations();
mItemAnimator.setListener(null);
}
mItemAnimator = animator;
if (mItemAnimator != null) {
mItemAnimator.setListener(mItemAnimatorListener);
}
}
/**
* Gets the current ItemAnimator for this RecyclerView. A null return value
* indicates that there is no animator and that item changes will happen without
* any animations. By default, RecyclerView instantiates and
* uses an instance of {@link DefaultItemAnimator}.
*
* @return ItemAnimator The current ItemAnimator. If null, no animations will occur
* when changes occur to the items in this RecyclerView.
*/
public ItemAnimator getItemAnimator() {
return mItemAnimator;
}
private boolean supportsChangeAnimations() {
return mItemAnimator != null && mItemAnimator.getSupportsChangeAnimations();
}
/**
* Post a runnable to the next frame to run pending item animations. Only the first such
* request will be posted, governed by the mPostedAnimatorRunner flag.
*/
private void postAnimationRunner() {
if (!mPostedAnimatorRunner && mIsAttached) {
ViewCompat.postOnAnimation(this, mItemAnimatorRunner);
mPostedAnimatorRunner = true;
}
}
private boolean predictiveItemAnimationsEnabled() {
return (mItemAnimator != null && mLayout.supportsPredictiveItemAnimations());
}
/**
* Consumes adapter updates and calculates which type of animations we want to run.
* Called in onMeasure and dispatchLayout.
* <p>
* This method may process only the pre-layout state of updates or all of them.
*/
private void processAdapterUpdatesAndSetAnimationFlags() {
if (mDataSetHasChangedAfterLayout) {
// Processing these items have no value since data set changed unexpectedly.
// Instead, we just reset it.
mAdapterHelper.reset();
markKnownViewsInvalid();
mLayout.onItemsChanged(this);
}
// simple animations are a subset of advanced animations (which will cause a
// pre-layout step)
// If layout supports predictive animations, pre-process to decide if we want to run them
if (mItemAnimator != null && mLayout.supportsPredictiveItemAnimations()) {
mAdapterHelper.preProcess();
} else {
mAdapterHelper.consumeUpdatesInOnePass();
}
boolean animationTypeSupported = (mItemsAddedOrRemoved && !mItemsChanged) ||
(mItemsAddedOrRemoved || (mItemsChanged && supportsChangeAnimations()));
mState.mRunSimpleAnimations = mFirstLayoutComplete && mItemAnimator != null &&
(mDataSetHasChangedAfterLayout || animationTypeSupported ||
mLayout.mRequestedSimpleAnimations) &&
(!mDataSetHasChangedAfterLayout || mAdapter.hasStableIds());
mState.mRunPredictiveAnimations = mState.mRunSimpleAnimations &&
animationTypeSupported && !mDataSetHasChangedAfterLayout &&
predictiveItemAnimationsEnabled();
}
/**
* Wrapper around layoutChildren() that handles animating changes caused by layout.
* Animations work on the assumption that there are five different kinds of items
* in play:
* PERSISTENT: items are visible before and after layout
* REMOVED: items were visible before layout and were removed by the app
* ADDED: items did not exist before layout and were added by the app
* DISAPPEARING: items exist in the data set before/after, but changed from
* visible to non-visible in the process of layout (they were moved off
* screen as a side-effect of other changes)
* APPEARING: items exist in the data set before/after, but changed from
* non-visible to visible in the process of layout (they were moved on
* screen as a side-effect of other changes)
* The overall approach figures out what items exist before/after layout and
* infers one of the five above states for each of the items. Then the animations
* are set up accordingly:
* PERSISTENT views are moved ({@link ItemAnimator#animateMove(ViewHolder, int, int, int, int)})
* REMOVED views are removed ({@link ItemAnimator#animateRemove(ViewHolder)})
* ADDED views are added ({@link ItemAnimator#animateAdd(ViewHolder)})
* DISAPPEARING views are moved off screen
* APPEARING views are moved on screen
*/
void dispatchLayout() {
if (mAdapter == null) {
Log.e(TAG, "No adapter attached; skipping layout");
return;
}
if (mLayout == null) {
Log.e(TAG, "No layout manager attached; skipping layout");
return;
}
mDisappearingViewsInLayoutPass.clear();
eatRequestLayout();
mRunningLayoutOrScroll = true;
processAdapterUpdatesAndSetAnimationFlags();
mState.mOldChangedHolders = mState.mRunSimpleAnimations && mItemsChanged
&& supportsChangeAnimations() ? new ArrayMap<Long, ViewHolder>() : null;
mItemsAddedOrRemoved = mItemsChanged = false;
ArrayMap<View, Rect> appearingViewInitialBounds = null;
mState.mInPreLayout = mState.mRunPredictiveAnimations;
mState.mItemCount = mAdapter.getItemCount();
findMinMaxChildLayoutPositions(mMinMaxLayoutPositions);
if (mState.mRunSimpleAnimations) {
// Step 0: Find out where all non-removed items are, pre-layout
mState.mPreLayoutHolderMap.clear();
mState.mPostLayoutHolderMap.clear();
int count = mChildHelper.getChildCount();
for (int i = 0; i < count; ++i) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i));
if (holder.shouldIgnore() || (holder.isInvalid() && !mAdapter.hasStableIds())) {
continue;
}
final View view = holder.itemView;
mState.mPreLayoutHolderMap.put(holder, new ItemHolderInfo(holder,
view.getLeft(), view.getTop(), view.getRight(), view.getBottom()));
}
}
if (mState.mRunPredictiveAnimations) {
// Step 1: run prelayout: This will use the old positions of items. The layout manager
// is expected to layout everything, even removed items (though not to add removed
// items back to the container). This gives the pre-layout position of APPEARING views
// which come into existence as part of the real layout.
// Save old positions so that LayoutManager can run its mapping logic.
saveOldPositions();
// processAdapterUpdatesAndSetAnimationFlags already run pre-layout animations.
if (mState.mOldChangedHolders != null) {
int count = mChildHelper.getChildCount();
for (int i = 0; i < count; ++i) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i));
if (holder.isChanged() && !holder.isRemoved() && !holder.shouldIgnore()) {
long key = getChangedHolderKey(holder);
mState.mOldChangedHolders.put(key, holder);
mState.mPreLayoutHolderMap.remove(holder);
}
}
}
final boolean didStructureChange = mState.mStructureChanged;
mState.mStructureChanged = false;
// temporarily disable flag because we are asking for previous layout
mLayout.onLayoutChildren(mRecycler, mState);
mState.mStructureChanged = didStructureChange;
appearingViewInitialBounds = new ArrayMap<View, Rect>();
for (int i = 0; i < mChildHelper.getChildCount(); ++i) {
boolean found = false;
View child = mChildHelper.getChildAt(i);
if (getChildViewHolderInt(child).shouldIgnore()) {
continue;
}
for (int j = 0; j < mState.mPreLayoutHolderMap.size(); ++j) {
ViewHolder holder = mState.mPreLayoutHolderMap.keyAt(j);
if (holder.itemView == child) {
found = true;
break;
}
}
if (!found) {
appearingViewInitialBounds.put(child, new Rect(child.getLeft(), child.getTop(),
child.getRight(), child.getBottom()));
}
}
// we don't process disappearing list because they may re-appear in post layout pass.
clearOldPositions();
mAdapterHelper.consumePostponedUpdates();
} else {
clearOldPositions();
// in case pre layout did run but we decided not to run predictive animations.
mAdapterHelper.consumeUpdatesInOnePass();
if (mState.mOldChangedHolders != null) {
int count = mChildHelper.getChildCount();
for (int i = 0; i < count; ++i) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i));
if (holder.isChanged() && !holder.isRemoved() && !holder.shouldIgnore()) {
long key = getChangedHolderKey(holder);
mState.mOldChangedHolders.put(key, holder);
mState.mPreLayoutHolderMap.remove(holder);
}
}
}
}
mState.mItemCount = mAdapter.getItemCount();
mState.mDeletedInvisibleItemCountSincePreviousLayout = 0;
// Step 2: Run layout
mState.mInPreLayout = false;
mLayout.onLayoutChildren(mRecycler, mState);
mState.mStructureChanged = false;
mPendingSavedState = null;
// onLayoutChildren may have caused client code to disable item animations; re-check
mState.mRunSimpleAnimations = mState.mRunSimpleAnimations && mItemAnimator != null;
if (mState.mRunSimpleAnimations) {
// Step 3: Find out where things are now, post-layout
ArrayMap<Long, ViewHolder> newChangedHolders = mState.mOldChangedHolders != null ?
new ArrayMap<Long, ViewHolder>() : null;
int count = mChildHelper.getChildCount();
for (int i = 0; i < count; ++i) {
ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i));
if (holder.shouldIgnore()) {
continue;
}
final View view = holder.itemView;
long key = getChangedHolderKey(holder);
if (newChangedHolders != null && mState.mOldChangedHolders.get(key) != null) {
newChangedHolders.put(key, holder);
} else {
mState.mPostLayoutHolderMap.put(holder, new ItemHolderInfo(holder,
view.getLeft(), view.getTop(), view.getRight(), view.getBottom()));
}
}
processDisappearingList(appearingViewInitialBounds);
// Step 4: Animate DISAPPEARING and REMOVED items
int preLayoutCount = mState.mPreLayoutHolderMap.size();
for (int i = preLayoutCount - 1; i >= 0; i--) {
ViewHolder itemHolder = mState.mPreLayoutHolderMap.keyAt(i);
if (!mState.mPostLayoutHolderMap.containsKey(itemHolder)) {
ItemHolderInfo disappearingItem = mState.mPreLayoutHolderMap.valueAt(i);
mState.mPreLayoutHolderMap.removeAt(i);
View disappearingItemView = disappearingItem.holder.itemView;
mRecycler.unscrapView(disappearingItem.holder);
animateDisappearance(disappearingItem);
}
}
// Step 5: Animate APPEARING and ADDED items
int postLayoutCount = mState.mPostLayoutHolderMap.size();
if (postLayoutCount > 0) {
for (int i = postLayoutCount - 1; i >= 0; i--) {
ViewHolder itemHolder = mState.mPostLayoutHolderMap.keyAt(i);
ItemHolderInfo info = mState.mPostLayoutHolderMap.valueAt(i);
if ((mState.mPreLayoutHolderMap.isEmpty() ||
!mState.mPreLayoutHolderMap.containsKey(itemHolder))) {
mState.mPostLayoutHolderMap.removeAt(i);
Rect initialBounds = (appearingViewInitialBounds != null) ?
appearingViewInitialBounds.get(itemHolder.itemView) : null;
animateAppearance(itemHolder, initialBounds,
info.left, info.top);
}
}
}
// Step 6: Animate PERSISTENT items
count = mState.mPostLayoutHolderMap.size();
for (int i = 0; i < count; ++i) {
ViewHolder postHolder = mState.mPostLayoutHolderMap.keyAt(i);
ItemHolderInfo postInfo = mState.mPostLayoutHolderMap.valueAt(i);
ItemHolderInfo preInfo = mState.mPreLayoutHolderMap.get(postHolder);
if (preInfo != null && postInfo != null) {
if (preInfo.left != postInfo.left || preInfo.top != postInfo.top) {
postHolder.setIsRecyclable(false);
if (DEBUG) {
Log.d(TAG, "PERSISTENT: " + postHolder +
" with view " + postHolder.itemView);
}
if (mItemAnimator.animateMove(postHolder,
preInfo.left, preInfo.top, postInfo.left, postInfo.top)) {
postAnimationRunner();
}
}
}
}
// Step 7: Animate CHANGING items
count = mState.mOldChangedHolders != null ? mState.mOldChangedHolders.size() : 0;
// traverse reverse in case view gets recycled while we are traversing the list.
for (int i = count - 1; i >= 0; i--) {
long key = mState.mOldChangedHolders.keyAt(i);
ViewHolder oldHolder = mState.mOldChangedHolders.get(key);
View oldView = oldHolder.itemView;
if (oldHolder.shouldIgnore()) {
continue;
}
// We probably don't need this check anymore since these views are removed from
// the list if they are recycled.
if (mRecycler.mChangedScrap != null &&
mRecycler.mChangedScrap.contains(oldHolder)) {
animateChange(oldHolder, newChangedHolders.get(key));
} else if (DEBUG) {
Log.e(TAG, "cannot find old changed holder in changed scrap :/" + oldHolder);
}
}
}
resumeRequestLayout(false);
mLayout.removeAndRecycleScrapInt(mRecycler);
mState.mPreviousLayoutItemCount = mState.mItemCount;
mDataSetHasChangedAfterLayout = false;
mState.mRunSimpleAnimations = false;
mState.mRunPredictiveAnimations = false;
mRunningLayoutOrScroll = false;
mLayout.mRequestedSimpleAnimations = false;
if (mRecycler.mChangedScrap != null) {
mRecycler.mChangedScrap.clear();
}
mState.mOldChangedHolders = null;
if (didChildRangeChange(mMinMaxLayoutPositions[0], mMinMaxLayoutPositions[1])) {
notifyOnScrolled(0, 0);
}
}
private void findMinMaxChildLayoutPositions(int[] into) {
final int count = mChildHelper.getChildCount();
if (count == 0) {
into[0] = 0;
into[1] = 0;
return;
}
int minPositionPreLayout = Integer.MAX_VALUE;
int maxPositionPreLayout = Integer.MIN_VALUE;
for (int i = 0; i < count; ++i) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i));
if (holder.shouldIgnore()) {
continue;
}
final int pos = holder.getLayoutPosition();
if (pos < minPositionPreLayout) {
minPositionPreLayout = pos;
}
if (pos > maxPositionPreLayout) {
maxPositionPreLayout = pos;
}
}
into[0] = minPositionPreLayout;
into[1] = maxPositionPreLayout;
}
private boolean didChildRangeChange(int minPositionPreLayout, int maxPositionPreLayout) {
int count = mChildHelper.getChildCount();
if (count == 0) {
return minPositionPreLayout != 0 || maxPositionPreLayout != 0;
}
for (int i = 0; i < count; ++i) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i));
if (holder.shouldIgnore()) {
continue;
}
final int pos = holder.getLayoutPosition();
if (pos < minPositionPreLayout || pos > maxPositionPreLayout) {
return true;
}
}
return false;
}
@Override
protected void removeDetachedView(View child, boolean animate) {
ViewHolder vh = getChildViewHolderInt(child);
if (vh != null) {
if (vh.isTmpDetached()) {
vh.clearTmpDetachFlag();
} else if (!vh.shouldIgnore()) {
throw new IllegalArgumentException("Called removeDetachedView with a view which"
+ " is not flagged as tmp detached." + vh);
}
}
dispatchChildDetached(child);
super.removeDetachedView(child, animate);
}
/**
* Returns a unique key to be used while handling change animations.
* It might be child's position or stable id depending on the adapter type.
*/
long getChangedHolderKey(ViewHolder holder) {
return mAdapter.hasStableIds() ? holder.getItemId() : holder.mPosition;
}
/**
* A LayoutManager may want to layout a view just to animate disappearance.
* This method handles those views and triggers remove animation on them.
*/
private void processDisappearingList(ArrayMap<View, Rect> appearingViews) {
final int count = mDisappearingViewsInLayoutPass.size();
for (int i = 0; i < count; i ++) {
View view = mDisappearingViewsInLayoutPass.get(i);
ViewHolder vh = getChildViewHolderInt(view);
final ItemHolderInfo info = mState.mPreLayoutHolderMap.remove(vh);
if (!mState.isPreLayout()) {
mState.mPostLayoutHolderMap.remove(vh);
}
if (appearingViews.remove(view) != null) {
mLayout.removeAndRecycleView(view, mRecycler);
continue;
}
if (info != null) {
animateDisappearance(info);
} else {
// let it disappear from the position it becomes visible
animateDisappearance(new ItemHolderInfo(vh, view.getLeft(), view.getTop(),
view.getRight(), view.getBottom()));
}
}
mDisappearingViewsInLayoutPass.clear();
}
private void animateAppearance(ViewHolder itemHolder, Rect beforeBounds, int afterLeft,
int afterTop) {
View newItemView = itemHolder.itemView;
if (beforeBounds != null &&
(beforeBounds.left != afterLeft || beforeBounds.top != afterTop)) {
// slide items in if before/after locations differ
itemHolder.setIsRecyclable(false);
if (DEBUG) {
Log.d(TAG, "APPEARING: " + itemHolder + " with view " + newItemView);
}
if (mItemAnimator.animateMove(itemHolder,
beforeBounds.left, beforeBounds.top,
afterLeft, afterTop)) {
postAnimationRunner();
}
} else {
if (DEBUG) {
Log.d(TAG, "ADDED: " + itemHolder + " with view " + newItemView);
}
itemHolder.setIsRecyclable(false);
if (mItemAnimator.animateAdd(itemHolder)) {
postAnimationRunner();
}
}
}
private void animateDisappearance(ItemHolderInfo disappearingItem) {
View disappearingItemView = disappearingItem.holder.itemView;
addAnimatingView(disappearingItem.holder);
int oldLeft = disappearingItem.left;
int oldTop = disappearingItem.top;
int newLeft = disappearingItemView.getLeft();
int newTop = disappearingItemView.getTop();
if (oldLeft != newLeft || oldTop != newTop) {
disappearingItem.holder.setIsRecyclable(false);
disappearingItemView.layout(newLeft, newTop,
newLeft + disappearingItemView.getWidth(),
newTop + disappearingItemView.getHeight());
if (DEBUG) {
Log.d(TAG, "DISAPPEARING: " + disappearingItem.holder +
" with view " + disappearingItemView);
}
if (mItemAnimator.animateMove(disappearingItem.holder, oldLeft, oldTop,
newLeft, newTop)) {
postAnimationRunner();
}
} else {
if (DEBUG) {
Log.d(TAG, "REMOVED: " + disappearingItem.holder +
" with view " + disappearingItemView);
}
disappearingItem.holder.setIsRecyclable(false);
if (mItemAnimator.animateRemove(disappearingItem.holder)) {
postAnimationRunner();
}
}
}
private void animateChange(ViewHolder oldHolder, ViewHolder newHolder) {
oldHolder.setIsRecyclable(false);
addAnimatingView(oldHolder);
oldHolder.mShadowedHolder = newHolder;
mRecycler.unscrapView(oldHolder);
if (DEBUG) {
Log.d(TAG, "CHANGED: " + oldHolder + " with view " + oldHolder.itemView);
}
final int fromLeft = oldHolder.itemView.getLeft();
final int fromTop = oldHolder.itemView.getTop();
final int toLeft, toTop;
if (newHolder == null || newHolder.shouldIgnore()) {
toLeft = fromLeft;
toTop = fromTop;
} else {
toLeft = newHolder.itemView.getLeft();
toTop = newHolder.itemView.getTop();
newHolder.setIsRecyclable(false);
newHolder.mShadowingHolder = oldHolder;
}
if(mItemAnimator.animateChange(oldHolder, newHolder,
fromLeft, fromTop, toLeft, toTop)) {
postAnimationRunner();
}
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
eatRequestLayout();
dispatchLayout();
resumeRequestLayout(false);
mFirstLayoutComplete = true;
}
@Override
public void requestLayout() {
if (!mEatRequestLayout) {
super.requestLayout();
} else {
mLayoutRequestEaten = true;
}
}
void markItemDecorInsetsDirty() {
final int childCount = mChildHelper.getUnfilteredChildCount();
for (int i = 0; i < childCount; i++) {
final View child = mChildHelper.getUnfilteredChildAt(i);
((LayoutParams) child.getLayoutParams()).mInsetsDirty = true;
}
mRecycler.markItemDecorInsetsDirty();
}
@Override
public void draw(Canvas c) {
super.draw(c);
final int count = mItemDecorations.size();
for (int i = 0; i < count; i++) {
mItemDecorations.get(i).onDrawOver(c, this, mState);
}
// TODO If padding is not 0 and chilChildrenToPadding is false, to draw glows properly, we
// need find children closest to edges. Not sure if it is worth the effort.
boolean needsInvalidate = false;
if (mLeftGlow != null && !mLeftGlow.isFinished()) {
final int restore = c.save();
final int padding = mClipToPadding ? getPaddingBottom() : 0;
c.rotate(270);
c.translate(-getHeight() + padding, 0);
needsInvalidate = mLeftGlow != null && mLeftGlow.draw(c);
c.restoreToCount(restore);
}
if (mTopGlow != null && !mTopGlow.isFinished()) {
final int restore = c.save();
if (mClipToPadding) {
c.translate(getPaddingLeft(), getPaddingTop());
}
needsInvalidate |= mTopGlow != null && mTopGlow.draw(c);
c.restoreToCount(restore);
}
if (mRightGlow != null && !mRightGlow.isFinished()) {
final int restore = c.save();
final int width = getWidth();
final int padding = mClipToPadding ? getPaddingTop() : 0;
c.rotate(90);
c.translate(-padding, -width);
needsInvalidate |= mRightGlow != null && mRightGlow.draw(c);
c.restoreToCount(restore);
}
if (mBottomGlow != null && !mBottomGlow.isFinished()) {
final int restore = c.save();
c.rotate(180);
if (mClipToPadding) {
c.translate(-getWidth() + getPaddingRight(), -getHeight() + getPaddingBottom());
} else {
c.translate(-getWidth(), -getHeight());
}
needsInvalidate |= mBottomGlow != null && mBottomGlow.draw(c);
c.restoreToCount(restore);
}
// If some views are animating, ItemDecorators are likely to move/change with them.
// Invalidate RecyclerView to re-draw decorators. This is still efficient because children's
// display lists are not invalidated.
if (!needsInvalidate && mItemAnimator != null && mItemDecorations.size() > 0 &&
mItemAnimator.isRunning()) {
needsInvalidate = true;
}
if (needsInvalidate) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
@Override
public void onDraw(Canvas c) {
super.onDraw(c);
final int count = mItemDecorations.size();
for (int i = 0; i < count; i++) {
mItemDecorations.get(i).onDraw(c, this, mState);
}
}
@Override
protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
return p instanceof LayoutParams && mLayout.checkLayoutParams((LayoutParams) p);
}
@Override
protected ViewGroup.LayoutParams generateDefaultLayoutParams() {
if (mLayout == null) {
throw new IllegalStateException("RecyclerView has no LayoutManager");
}
return mLayout.generateDefaultLayoutParams();
}
@Override
public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) {
if (mLayout == null) {
throw new IllegalStateException("RecyclerView has no LayoutManager");
}
return mLayout.generateLayoutParams(getContext(), attrs);
}
@Override
protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {
if (mLayout == null) {
throw new IllegalStateException("RecyclerView has no LayoutManager");
}
return mLayout.generateLayoutParams(p);
}
void saveOldPositions() {
final int childCount = mChildHelper.getUnfilteredChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i));
if (DEBUG && holder.mPosition == -1 && !holder.isRemoved()) {
throw new IllegalStateException("view holder cannot have position -1 unless it"
+ " is removed");
}
if (!holder.shouldIgnore()) {
holder.saveOldPosition();
}
}
}
void clearOldPositions() {
final int childCount = mChildHelper.getUnfilteredChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i));
if (!holder.shouldIgnore()) {
holder.clearOldPosition();
}
}
mRecycler.clearOldPositions();
}
void offsetPositionRecordsForMove(int from, int to) {
final int childCount = mChildHelper.getUnfilteredChildCount();
final int start, end, inBetweenOffset;
if (from < to) {
start = from;
end = to;
inBetweenOffset = -1;
} else {
start = to;
end = from;
inBetweenOffset = 1;
}
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i));
if (holder == null || holder.mPosition < start || holder.mPosition > end) {
continue;
}
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForMove attached child " + i + " holder " +
holder);
}
if (holder.mPosition == from) {
holder.offsetPosition(to - from, false);
} else {
holder.offsetPosition(inBetweenOffset, false);
}
mState.mStructureChanged = true;
}
mRecycler.offsetPositionRecordsForMove(from, to);
requestLayout();
}
void offsetPositionRecordsForInsert(int positionStart, int itemCount) {
final int childCount = mChildHelper.getUnfilteredChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i));
if (holder != null && !holder.shouldIgnore() && holder.mPosition >= positionStart) {
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForInsert attached child " + i + " holder " +
holder + " now at position " + (holder.mPosition + itemCount));
}
holder.offsetPosition(itemCount, false);
mState.mStructureChanged = true;
}
}
mRecycler.offsetPositionRecordsForInsert(positionStart, itemCount);
requestLayout();
}
void offsetPositionRecordsForRemove(int positionStart, int itemCount,
boolean applyToPreLayout) {
final int positionEnd = positionStart + itemCount;
final int childCount = mChildHelper.getUnfilteredChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i));
if (holder != null && !holder.shouldIgnore()) {
if (holder.mPosition >= positionEnd) {
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForRemove attached child " + i +
" holder " + holder + " now at position " +
(holder.mPosition - itemCount));
}
holder.offsetPosition(-itemCount, applyToPreLayout);
mState.mStructureChanged = true;
} else if (holder.mPosition >= positionStart) {
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForRemove attached child " + i +
" holder " + holder + " now REMOVED");
}
holder.flagRemovedAndOffsetPosition(positionStart - 1, -itemCount,
applyToPreLayout);
mState.mStructureChanged = true;
}
}
}
mRecycler.offsetPositionRecordsForRemove(positionStart, itemCount, applyToPreLayout);
requestLayout();
}
/**
* Rebind existing views for the given range, or create as needed.
*
* @param positionStart Adapter position to start at
* @param itemCount Number of views that must explicitly be rebound
*/
void viewRangeUpdate(int positionStart, int itemCount) {
final int childCount = mChildHelper.getUnfilteredChildCount();
final int positionEnd = positionStart + itemCount;
for (int i = 0; i < childCount; i++) {
final View child = mChildHelper.getUnfilteredChildAt(i);
final ViewHolder holder = getChildViewHolderInt(child);
if (holder == null || holder.shouldIgnore()) {
continue;
}
if (holder.mPosition >= positionStart && holder.mPosition < positionEnd) {
// We re-bind these view holders after pre-processing is complete so that
// ViewHolders have their final positions assigned.
holder.addFlags(ViewHolder.FLAG_UPDATE);
if (supportsChangeAnimations()) {
holder.addFlags(ViewHolder.FLAG_CHANGED);
}
// lp cannot be null since we get ViewHolder from it.
((LayoutParams) child.getLayoutParams()).mInsetsDirty = true;
}
}
mRecycler.viewRangeUpdate(positionStart, itemCount);
}
void rebindUpdatedViewHolders() {
final int childCount = mChildHelper.getChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i));
// validate type is correct
if (holder == null || holder.shouldIgnore()) {
continue;
}
if (holder.isRemoved() || holder.isInvalid()) {
requestLayout();
} else if (holder.needsUpdate()) {
final int type = mAdapter.getItemViewType(holder.mPosition);
if (holder.getItemViewType() == type) {
// Binding an attached view will request a layout if needed.
if (!holder.isChanged() || !supportsChangeAnimations()) {
mAdapter.bindViewHolder(holder, holder.mPosition);
} else {
// Don't rebind changed holders if change animations are enabled.
// We want the old contents for the animation and will get a new
// holder for the new contents.
requestLayout();
}
} else {
// binding to a new view will need re-layout anyways. We can as well trigger
// it here so that it happens during layout
holder.addFlags(ViewHolder.FLAG_INVALID);
requestLayout();
}
}
}
}
private void setDataSetChangedAfterLayout() {
if (mDataSetHasChangedAfterLayout) {
return;
}
mDataSetHasChangedAfterLayout = true;
final int childCount = mChildHelper.getUnfilteredChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i));
if (holder != null && !holder.shouldIgnore()) {
holder.addFlags(ViewHolder.FLAG_ADAPTER_POSITION_UNKNOWN);
}
}
mRecycler.setAdapterPositionsAsUnknown();
}
/**
* Mark all known views as invalid. Used in response to a, "the whole world might have changed"
* data change event.
*/
void markKnownViewsInvalid() {
final int childCount = mChildHelper.getUnfilteredChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i));
if (holder != null && !holder.shouldIgnore()) {
holder.addFlags(ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID);
}
}
markItemDecorInsetsDirty();
mRecycler.markKnownViewsInvalid();
}
/**
* Invalidates all ItemDecorations. If RecyclerView has item decorations, calling this method
* will trigger a {@link #requestLayout()} call.
*/
public void invalidateItemDecorations() {
if (mItemDecorations.size() == 0) {
return;
}
if (mLayout != null) {
mLayout.assertNotInLayoutOrScroll("Cannot invalidate item decorations during a scroll"
+ " or layout");
}
markItemDecorInsetsDirty();
requestLayout();
}
/**
* Retrieve the {@link ViewHolder} for the given child view.
*
* @param child Child of this RecyclerView to query for its ViewHolder
* @return The child view's ViewHolder
*/
public ViewHolder getChildViewHolder(View child) {
final ViewParent parent = child.getParent();
if (parent != null && parent != this) {
throw new IllegalArgumentException("View " + child + " is not a direct child of " +
this);
}
return getChildViewHolderInt(child);
}
static ViewHolder getChildViewHolderInt(View child) {
if (child == null) {
return null;
}
return ((LayoutParams) child.getLayoutParams()).mViewHolder;
}
/**
* @deprecated use {@link #getChildAdapterPosition(View)} or
* {@link #getChildLayoutPosition(View)}.
*/
@Deprecated
public int getChildPosition(View child) {
return getChildAdapterPosition(child);
}
/**
* Return the adapter position that the given child view corresponds to.
*
* @param child Child View to query
* @return Adapter position corresponding to the given view or {@link #NO_POSITION}
*/
public int getChildAdapterPosition(View child) {
final ViewHolder holder = getChildViewHolderInt(child);
return holder != null ? holder.getAdapterPosition() : NO_POSITION;
}
/**
* Return the adapter position of the given child view as of the latest completed layout pass.
* <p>
* This position may not be equal to Item's adapter position if there are pending changes
* in the adapter which have not been reflected to the layout yet.
*
* @param child Child View to query
* @return Adapter position of the given View as of last layout pass or {@link #NO_POSITION} if
* the View is representing a removed item.
*/
public int getChildLayoutPosition(View child) {
final ViewHolder holder = getChildViewHolderInt(child);
return holder != null ? holder.getLayoutPosition() : NO_POSITION;
}
/**
* Return the stable item id that the given child view corresponds to.
*
* @param child Child View to query
* @return Item id corresponding to the given view or {@link #NO_ID}
*/
public long getChildItemId(View child) {
if (mAdapter == null || !mAdapter.hasStableIds()) {
return NO_ID;
}
final ViewHolder holder = getChildViewHolderInt(child);
return holder != null ? holder.getItemId() : NO_ID;
}
/**
* @deprecated use {@link #findViewHolderForLayoutPosition(int)} or
* {@link #findViewHolderForAdapterPosition(int)}
*/
@Deprecated
public ViewHolder findViewHolderForPosition(int position) {
return findViewHolderForPosition(position, false);
}
/**
* Return the ViewHolder for the item in the given position of the data set as of the latest
* layout pass.
* <p>
* This method checks only the children of RecyclerView. If the item at the given
* <code>position</code> is not laid out, it <em>will not</em> create a new one.
* <p>
* Note that when Adapter contents change, ViewHolder positions are not updated until the
* next layout calculation. If there are pending adapter updates, the return value of this
* method may not match your adapter contents. You can use
* #{@link ViewHolder#getAdapterPosition()} to get the current adapter position of a ViewHolder.
*
* @param position The position of the item in the data set of the adapter
* @return The ViewHolder at <code>position</code> or null if there is no such item
*/
public ViewHolder findViewHolderForLayoutPosition(int position) {
return findViewHolderForPosition(position, false);
}
/**
* Return the ViewHolder for the item in the given position of the data set. Unlike
* {@link #findViewHolderForLayoutPosition(int)} this method takes into account any pending
* adapter changes that may not be reflected to the layout yet. On the other hand, if
* {@link Adapter#notifyDataSetChanged()} has been called but the new layout has not been
* calculated yet, this method will return <code>null</code> since the new positions of views
* are unknown until the layout is calculated.
* <p>
* This method checks only the children of RecyclerView. If the item at the given
* <code>position</code> is not laid out, it <em>will not</em> create a new one.
*
* @param position The position of the item in the data set of the adapter
* @return The ViewHolder at <code>position</code> or null if there is no such item
*/
public ViewHolder findViewHolderForAdapterPosition(int position) {
if (mDataSetHasChangedAfterLayout) {
return null;
}
final int childCount = mChildHelper.getUnfilteredChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i));
if (holder != null && !holder.isRemoved() && getAdapterPositionFor(holder) == position) {
return holder;
}
}
return null;
}
ViewHolder findViewHolderForPosition(int position, boolean checkNewPosition) {
final int childCount = mChildHelper.getUnfilteredChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i));
if (holder != null && !holder.isRemoved()) {
if (checkNewPosition) {
if (holder.mPosition == position) {
return holder;
}
} else if (holder.getLayoutPosition() == position) {
return holder;
}
}
}
// This method should not query cached views. It creates a problem during adapter updates
// when we are dealing with already laid out views. Also, for the public method, it is more
// reasonable to return null if position is not laid out.
return null;
}
/**
* Return the ViewHolder for the item with the given id. The RecyclerView must
* use an Adapter with {@link Adapter#setHasStableIds(boolean) stableIds} to
* return a non-null value.
* <p>
* This method checks only the children of RecyclerView. If the item with the given
* <code>id</code> is not laid out, it <em>will not</em> create a new one.
*
* @param id The id for the requested item
* @return The ViewHolder with the given <code>id</code> or null if there is no such item
*/
public ViewHolder findViewHolderForItemId(long id) {
final int childCount = mChildHelper.getUnfilteredChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i));
if (holder != null && holder.getItemId() == id) {
return holder;
}
}
// this method should not query cached views. They are not children so they
// should not be returned in this public method
return null;
}
/**
* Find the topmost view under the given point.
*
* @param x Horizontal position in pixels to search
* @param y Vertical position in pixels to search
* @return The child view under (x, y) or null if no matching child is found
*/
public View findChildViewUnder(float x, float y) {
final int count = mChildHelper.getChildCount();
for (int i = count - 1; i >= 0; i--) {
final View child = mChildHelper.getChildAt(i);
final float translationX = ViewCompat.getTranslationX(child);
final float translationY = ViewCompat.getTranslationY(child);
if (x >= child.getLeft() + translationX &&
x <= child.getRight() + translationX &&
y >= child.getTop() + translationY &&
y <= child.getBottom() + translationY) {
return child;
}
}
return null;
}
/**
* Offset the bounds of all child views by <code>dy</code> pixels.
* Useful for implementing simple scrolling in {@link LayoutManager LayoutManagers}.
*
* @param dy Vertical pixel offset to apply to the bounds of all child views
*/
public void offsetChildrenVertical(int dy) {
final int childCount = mChildHelper.getChildCount();
for (int i = 0; i < childCount; i++) {
mChildHelper.getChildAt(i).offsetTopAndBottom(dy);
}
}
/**
* Called when an item view is attached to this RecyclerView.
*
* <p>Subclasses of RecyclerView may want to perform extra bookkeeping or modifications
* of child views as they become attached. This will be called before a
* {@link LayoutManager} measures or lays out the view and is a good time to perform these
* changes.</p>
*
* @param child Child view that is now attached to this RecyclerView and its associated window
*/
public void onChildAttachedToWindow(View child) {
}
/**
* Called when an item view is detached from this RecyclerView.
*
* <p>Subclasses of RecyclerView may want to perform extra bookkeeping or modifications
* of child views as they become detached. This will be called as a
* {@link LayoutManager} fully detaches the child view from the parent and its window.</p>
*
* @param child Child view that is now detached from this RecyclerView and its associated window
*/
public void onChildDetachedFromWindow(View child) {
}
/**
* Offset the bounds of all child views by <code>dx</code> pixels.
* Useful for implementing simple scrolling in {@link LayoutManager LayoutManagers}.
*
* @param dx Horizontal pixel offset to apply to the bounds of all child views
*/
public void offsetChildrenHorizontal(int dx) {
final int childCount = mChildHelper.getChildCount();
for (int i = 0; i < childCount; i++) {
mChildHelper.getChildAt(i).offsetLeftAndRight(dx);
}
}
Rect getItemDecorInsetsForChild(View child) {
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
if (!lp.mInsetsDirty) {
return lp.mDecorInsets;
}
final Rect insets = lp.mDecorInsets;
insets.set(0, 0, 0, 0);
final int decorCount = mItemDecorations.size();
for (int i = 0; i < decorCount; i++) {
mTempRect.set(0, 0, 0, 0);
mItemDecorations.get(i).getItemOffsets(mTempRect, child, this, mState);
insets.left += mTempRect.left;
insets.top += mTempRect.top;
insets.right += mTempRect.right;
insets.bottom += mTempRect.bottom;
}
lp.mInsetsDirty = false;
return insets;
}
private class ViewFlinger implements Runnable {
private int mLastFlingX;
private int mLastFlingY;
private ScrollerCompat mScroller;
private Interpolator mInterpolator = sQuinticInterpolator;
// When set to true, postOnAnimation callbacks are delayed until the run method completes
private boolean mEatRunOnAnimationRequest = false;
// Tracks if postAnimationCallback should be re-attached when it is done
private boolean mReSchedulePostAnimationCallback = false;
public ViewFlinger() {
mScroller = ScrollerCompat.create(getContext(), sQuinticInterpolator);
}
@Override
public void run() {
disableRunOnAnimationRequests();
consumePendingUpdateOperations();
// keep a local reference so that if it is changed during onAnimation method, it won't
// cause unexpected behaviors
final ScrollerCompat scroller = mScroller;
final SmoothScroller smoothScroller = mLayout.mSmoothScroller;
if (scroller.computeScrollOffset()) {
final int x = scroller.getCurrX();
final int y = scroller.getCurrY();
final int dx = x - mLastFlingX;
final int dy = y - mLastFlingY;
int hresult = 0;
int vresult = 0;
mLastFlingX = x;
mLastFlingY = y;
int overscrollX = 0, overscrollY = 0;
if (mAdapter != null) {
eatRequestLayout();
mRunningLayoutOrScroll = true;
if (dx != 0) {
hresult = mLayout.scrollHorizontallyBy(dx, mRecycler, mState);
overscrollX = dx - hresult;
}
if (dy != 0) {
vresult = mLayout.scrollVerticallyBy(dy, mRecycler, mState);
overscrollY = dy - vresult;
}
if (supportsChangeAnimations()) {
// Fix up shadow views used by changing animations
int count = mChildHelper.getChildCount();
for (int i = 0; i < count; i++) {
View view = mChildHelper.getChildAt(i);
ViewHolder holder = getChildViewHolder(view);
if (holder != null && holder.mShadowingHolder != null) {
View shadowingView = holder.mShadowingHolder.itemView;
int left = view.getLeft();
int top = view.getTop();
if (left != shadowingView.getLeft() ||
top != shadowingView.getTop()) {
shadowingView.layout(left, top,
left + shadowingView.getWidth(),
top + shadowingView.getHeight());
}
}
}
}
if (smoothScroller != null && !smoothScroller.isPendingInitialRun() &&
smoothScroller.isRunning()) {
final int adapterSize = mState.getItemCount();
if (adapterSize == 0) {
smoothScroller.stop();
} else if (smoothScroller.getTargetPosition() >= adapterSize) {
smoothScroller.setTargetPosition(adapterSize - 1);
smoothScroller.onAnimation(dx - overscrollX, dy - overscrollY);
} else {
smoothScroller.onAnimation(dx - overscrollX, dy - overscrollY);
}
}
mRunningLayoutOrScroll = false;
resumeRequestLayout(false);
}
if (!mItemDecorations.isEmpty()) {
invalidate();
}
if (ViewCompat.getOverScrollMode(RecyclerView.this) !=
ViewCompat.OVER_SCROLL_NEVER) {
considerReleasingGlowsOnScroll(dx, dy);
}
if (overscrollX != 0 || overscrollY != 0) {
final int vel = (int) scroller.getCurrVelocity();
int velX = 0;
if (overscrollX != x) {
velX = overscrollX < 0 ? -vel : overscrollX > 0 ? vel : 0;
}
int velY = 0;
if (overscrollY != y) {
velY = overscrollY < 0 ? -vel : overscrollY > 0 ? vel : 0;
}
if (ViewCompat.getOverScrollMode(RecyclerView.this) !=
ViewCompat.OVER_SCROLL_NEVER) {
absorbGlows(velX, velY);
}
if ((velX != 0 || overscrollX == x || scroller.getFinalX() == 0) &&
(velY != 0 || overscrollY == y || scroller.getFinalY() == 0)) {
scroller.abortAnimation();
}
}
if (hresult != 0 || vresult != 0) {
notifyOnScrolled(hresult, vresult);
}
if (!awakenScrollBars()) {
invalidate();
}
final boolean fullyConsumedVertical = dy != 0 && mLayout.canScrollVertically()
&& vresult == dy;
final boolean fullyConsumedHorizontal = dx != 0 && mLayout.canScrollHorizontally()
&& hresult == dx;
final boolean fullyConsumedAny = (dx == 0 && dy == 0) || fullyConsumedHorizontal
|| fullyConsumedVertical;
if (scroller.isFinished() || !fullyConsumedAny) {
setScrollState(SCROLL_STATE_IDLE); // setting state to idle will stop this.
} else {
postOnAnimation();
}
}
// call this after the onAnimation is complete not to have inconsistent callbacks etc.
if (smoothScroller != null && smoothScroller.isPendingInitialRun()) {
smoothScroller.onAnimation(0, 0);
}
enableRunOnAnimationRequests();
}
private void disableRunOnAnimationRequests() {
mReSchedulePostAnimationCallback = false;
mEatRunOnAnimationRequest = true;
}
private void enableRunOnAnimationRequests() {
mEatRunOnAnimationRequest = false;
if (mReSchedulePostAnimationCallback) {
postOnAnimation();
}
}
void postOnAnimation() {
if (mEatRunOnAnimationRequest) {
mReSchedulePostAnimationCallback = true;
} else {
removeCallbacks(this);
ViewCompat.postOnAnimation(RecyclerView.this, this);
}
}
public void fling(int velocityX, int velocityY) {
setScrollState(SCROLL_STATE_SETTLING);
mLastFlingX = mLastFlingY = 0;
mScroller.fling(0, 0, velocityX, velocityY,
Integer.MIN_VALUE, Integer.MAX_VALUE, Integer.MIN_VALUE, Integer.MAX_VALUE);
postOnAnimation();
}
public void smoothScrollBy(int dx, int dy) {
smoothScrollBy(dx, dy, 0, 0);
}
public void smoothScrollBy(int dx, int dy, int vx, int vy) {
smoothScrollBy(dx, dy, computeScrollDuration(dx, dy, vx, vy));
}
private float distanceInfluenceForSnapDuration(float f) {
f -= 0.5f; // center the values about 0.
f *= 0.3f * Math.PI / 2.0f;
return (float) Math.sin(f);
}
private int computeScrollDuration(int dx, int dy, int vx, int vy) {
final int absDx = Math.abs(dx);
final int absDy = Math.abs(dy);
final boolean horizontal = absDx > absDy;
final int velocity = (int) Math.sqrt(vx * vx + vy * vy);
final int delta = (int) Math.sqrt(dx * dx + dy * dy);
final int containerSize = horizontal ? getWidth() : getHeight();
final int halfContainerSize = containerSize / 2;
final float distanceRatio = Math.min(1.f, 1.f * delta / containerSize);
final float distance = halfContainerSize + halfContainerSize *
distanceInfluenceForSnapDuration(distanceRatio);
final int duration;
if (velocity > 0) {
duration = 4 * Math.round(1000 * Math.abs(distance / velocity));
} else {
float absDelta = (float) (horizontal ? absDx : absDy);
duration = (int) (((absDelta / containerSize) + 1) * 300);
}
return Math.min(duration, MAX_SCROLL_DURATION);
}
public void smoothScrollBy(int dx, int dy, int duration) {
smoothScrollBy(dx, dy, duration, sQuinticInterpolator);
}
public void smoothScrollBy(int dx, int dy, int duration, Interpolator interpolator) {
if (mInterpolator != interpolator) {
mInterpolator = interpolator;
mScroller = ScrollerCompat.create(getContext(), interpolator);
}
setScrollState(SCROLL_STATE_SETTLING);
mLastFlingX = mLastFlingY = 0;
mScroller.startScroll(0, 0, dx, dy, duration);
postOnAnimation();
}
public void stop() {
removeCallbacks(this);
mScroller.abortAnimation();
}
}
private void notifyOnScrolled(int hresult, int vresult) {
// dummy values, View's implementation does not use these.
onScrollChanged(0, 0, 0, 0);
if (mScrollListener != null) {
mScrollListener.onScrolled(this, hresult, vresult);
}
}
private class RecyclerViewDataObserver extends AdapterDataObserver {
@Override
public void onChanged() {
assertNotInLayoutOrScroll(null);
if (mAdapter.hasStableIds()) {
// TODO Determine what actually changed.
// This is more important to implement now since this callback will disable all
// animations because we cannot rely on positions.
mState.mStructureChanged = true;
setDataSetChangedAfterLayout();
} else {
mState.mStructureChanged = true;
setDataSetChangedAfterLayout();
}
if (!mAdapterHelper.hasPendingUpdates()) {
requestLayout();
}
}
@Override
public void onItemRangeChanged(int positionStart, int itemCount) {
assertNotInLayoutOrScroll(null);
if (mAdapterHelper.onItemRangeChanged(positionStart, itemCount)) {
triggerUpdateProcessor();
}
}
@Override
public void onItemRangeInserted(int positionStart, int itemCount) {
assertNotInLayoutOrScroll(null);
if (mAdapterHelper.onItemRangeInserted(positionStart, itemCount)) {
triggerUpdateProcessor();
}
}
@Override
public void onItemRangeRemoved(int positionStart, int itemCount) {
assertNotInLayoutOrScroll(null);
if (mAdapterHelper.onItemRangeRemoved(positionStart, itemCount)) {
triggerUpdateProcessor();
}
}
@Override
public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
assertNotInLayoutOrScroll(null);
if (mAdapterHelper.onItemRangeMoved(fromPosition, toPosition, itemCount)) {
triggerUpdateProcessor();
}
}
void triggerUpdateProcessor() {
if (mPostUpdatesOnAnimation && mHasFixedSize && mIsAttached) {
ViewCompat.postOnAnimation(RecyclerView.this, mUpdateChildViewsRunnable);
} else {
mAdapterUpdateDuringMeasure = true;
requestLayout();
}
}
}
/**
* RecycledViewPool lets you share Views between multiple RecyclerViews.
* <p>
* If you want to recycle views across RecyclerViews, create an instance of RecycledViewPool
* and use {@link RecyclerView#setRecycledViewPool(RecycledViewPool)}.
* <p>
* RecyclerView automatically creates a pool for itself if you don't provide one.
*
*/
public static class RecycledViewPool {
private SparseArray<ArrayList<ViewHolder>> mScrap =
new SparseArray<ArrayList<ViewHolder>>();
private SparseIntArray mMaxScrap = new SparseIntArray();
private int mAttachCount = 0;
private static final int DEFAULT_MAX_SCRAP = 5;
public void clear() {
mScrap.clear();
}
public void setMaxRecycledViews(int viewType, int max) {
mMaxScrap.put(viewType, max);
final ArrayList<ViewHolder> scrapHeap = mScrap.get(viewType);
if (scrapHeap != null) {
while (scrapHeap.size() > max) {
scrapHeap.remove(scrapHeap.size() - 1);
}
}
}
public ViewHolder getRecycledView(int viewType) {
final ArrayList<ViewHolder> scrapHeap = mScrap.get(viewType);
if (scrapHeap != null && !scrapHeap.isEmpty()) {
final int index = scrapHeap.size() - 1;
final ViewHolder scrap = scrapHeap.get(index);
scrapHeap.remove(index);
return scrap;
}
return null;
}
int size() {
int count = 0;
for (int i = 0; i < mScrap.size(); i ++) {
ArrayList<ViewHolder> viewHolders = mScrap.valueAt(i);
if (viewHolders != null) {
count += viewHolders.size();
}
}
return count;
}
public void putRecycledView(ViewHolder scrap) {
final int viewType = scrap.getItemViewType();
final ArrayList scrapHeap = getScrapHeapForType(viewType);
if (mMaxScrap.get(viewType) <= scrapHeap.size()) {
return;
}
scrap.resetInternal();
scrapHeap.add(scrap);
}
void attach(Adapter adapter) {
mAttachCount++;
}
void detach() {
mAttachCount--;
}
/**
* Detaches the old adapter and attaches the new one.
* <p>
* RecycledViewPool will clear its cache if it has only one adapter attached and the new
* adapter uses a different ViewHolder than the oldAdapter.
*
* @param oldAdapter The previous adapter instance. Will be detached.
* @param newAdapter The new adapter instance. Will be attached.
* @param compatibleWithPrevious True if both oldAdapter and newAdapter are using the same
* ViewHolder and view types.
*/
void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter,
boolean compatibleWithPrevious) {
if (oldAdapter != null) {
detach();
}
if (!compatibleWithPrevious && mAttachCount == 0) {
clear();
}
if (newAdapter != null) {
attach(newAdapter);
}
}
private ArrayList<ViewHolder> getScrapHeapForType(int viewType) {
ArrayList<ViewHolder> scrap = mScrap.get(viewType);
if (scrap == null) {
scrap = new ArrayList<ViewHolder>();
mScrap.put(viewType, scrap);
if (mMaxScrap.indexOfKey(viewType) < 0) {
mMaxScrap.put(viewType, DEFAULT_MAX_SCRAP);
}
}
return scrap;
}
}
/**
* A Recycler is responsible for managing scrapped or detached item views for reuse.
*
* <p>A "scrapped" view is a view that is still attached to its parent RecyclerView but
* that has been marked for removal or reuse.</p>
*
* <p>Typical use of a Recycler by a {@link LayoutManager} will be to obtain views for
* an adapter's data set representing the data at a given position or item ID.
* If the view to be reused is considered "dirty" the adapter will be asked to rebind it.
* If not, the view can be quickly reused by the LayoutManager with no further work.
* Clean views that have not {@link android.view.View#isLayoutRequested() requested layout}
* may be repositioned by a LayoutManager without remeasurement.</p>
*/
public final class Recycler {
final ArrayList<ViewHolder> mAttachedScrap = new ArrayList<ViewHolder>();
private ArrayList<ViewHolder> mChangedScrap = null;
final ArrayList<ViewHolder> mCachedViews = new ArrayList<ViewHolder>();
private final List<ViewHolder>
mUnmodifiableAttachedScrap = Collections.unmodifiableList(mAttachedScrap);
private int mViewCacheMax = DEFAULT_CACHE_SIZE;
private RecycledViewPool mRecyclerPool;
private ViewCacheExtension mViewCacheExtension;
private static final int DEFAULT_CACHE_SIZE = 2;
/**
* Clear scrap views out of this recycler. Detached views contained within a
* recycled view pool will remain.
*/
public void clear() {
mAttachedScrap.clear();
recycleAndClearCachedViews();
}
/**
* Set the maximum number of detached, valid views we should retain for later use.
*
* @param viewCount Number of views to keep before sending views to the shared pool
*/
public void setViewCacheSize(int viewCount) {
mViewCacheMax = viewCount;
// first, try the views that can be recycled
for (int i = mCachedViews.size() - 1; i >= 0 && mCachedViews.size() > viewCount; i--) {
recycleCachedViewAt(i);
}
}
/**
* Returns an unmodifiable list of ViewHolders that are currently in the scrap list.
*
* @return List of ViewHolders in the scrap list.
*/
public List<ViewHolder> getScrapList() {
return mUnmodifiableAttachedScrap;
}
/**
* Helper method for getViewForPosition.
* <p>
* Checks whether a given view holder can be used for the provided position.
*
* @param holder ViewHolder
* @return true if ViewHolder matches the provided position, false otherwise
*/
boolean validateViewHolderForOffsetPosition(ViewHolder holder) {
// if it is a removed holder, nothing to verify since we cannot ask adapter anymore
// if it is not removed, verify the type and id.
if (holder.isRemoved()) {
return true;
}
if (holder.mPosition < 0 || holder.mPosition >= mAdapter.getItemCount()) {
throw new IndexOutOfBoundsException("Inconsistency detected. Invalid view holder "
+ "adapter position" + holder);
}
if (!mState.isPreLayout()) {
// don't check type if it is pre-layout.
final int type = mAdapter.getItemViewType(holder.mPosition);
if (type != holder.getItemViewType()) {
return false;
}
}
if (mAdapter.hasStableIds()) {
return holder.getItemId() == mAdapter.getItemId(holder.mPosition);
}
return true;
}
/**
* Binds the given View to the position. The View can be a View previously retrieved via
* {@link #getViewForPosition(int)} or created by
* {@link Adapter#onCreateViewHolder(ViewGroup, int)}.
* <p>
* Generally, a LayoutManager should acquire its views via {@link #getViewForPosition(int)}
* and let the RecyclerView handle caching. This is a helper method for LayoutManager who
* wants to handle its own recycling logic.
* <p>
* Note that, {@link #getViewForPosition(int)} already binds the View to the position so
* you don't need to call this method unless you want to bind this View to another position.
*
* @param view The view to update.
* @param position The position of the item to bind to this View.
*/
public void bindViewToPosition(View view, int position) {
ViewHolder holder = getChildViewHolderInt(view);
if (holder == null) {
throw new IllegalArgumentException("The view does not have a ViewHolder. You cannot"
+ " pass arbitrary views to this method, they should be created by the "
+ "Adapter");
}
final int offsetPosition = mAdapterHelper.findPositionOffset(position);
if (offsetPosition < 0 || offsetPosition >= mAdapter.getItemCount()) {
throw new IndexOutOfBoundsException("Inconsistency detected. Invalid item "
+ "position " + position + "(offset:" + offsetPosition + ")."
+ "state:" + mState.getItemCount());
}
mAdapter.bindViewHolder(holder, offsetPosition);
attachAccessibilityDelegate(view);
if (mState.isPreLayout()) {
holder.mPreLayoutPosition = position;
}
final ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();
final LayoutParams rvLayoutParams;
if (lp == null) {
rvLayoutParams = (LayoutParams) generateDefaultLayoutParams();
holder.itemView.setLayoutParams(rvLayoutParams);
} else if (!checkLayoutParams(lp)) {
rvLayoutParams = (LayoutParams) generateLayoutParams(lp);
holder.itemView.setLayoutParams(rvLayoutParams);
} else {
rvLayoutParams = (LayoutParams) lp;
}
rvLayoutParams.mInsetsDirty = true;
rvLayoutParams.mViewHolder = holder;
rvLayoutParams.mPendingInvalidate = holder.itemView.getParent() == null;
}
/**
* RecyclerView provides artificial position range (item count) in pre-layout state and
* automatically maps these positions to {@link Adapter} positions when
* {@link #getViewForPosition(int)} or {@link #bindViewToPosition(View, int)} is called.
* <p>
* Usually, LayoutManager does not need to worry about this. However, in some cases, your
* LayoutManager may need to call some custom component with item positions in which
* case you need the actual adapter position instead of the pre layout position. You
* can use this method to convert a pre-layout position to adapter (post layout) position.
* <p>
* Note that if the provided position belongs to a deleted ViewHolder, this method will
* return -1.
* <p>
* Calling this method in post-layout state returns the same value back.
*
* @param position The pre-layout position to convert. Must be greater or equal to 0 and
* less than {@link State#getItemCount()}.
*/
public int convertPreLayoutPositionToPostLayout(int position) {
if (position < 0 || position >= mState.getItemCount()) {
throw new IndexOutOfBoundsException("invalid position " + position + ". State "
+ "item count is " + mState.getItemCount());
}
if (!mState.isPreLayout()) {
return position;
}
return mAdapterHelper.findPositionOffset(position);
}
/**
* Obtain a view initialized for the given position.
*
* This method should be used by {@link LayoutManager} implementations to obtain
* views to represent data from an {@link Adapter}.
* <p>
* The Recycler may reuse a scrap or detached view from a shared pool if one is
* available for the correct view type. If the adapter has not indicated that the
* data at the given position has changed, the Recycler will attempt to hand back
* a scrap view that was previously initialized for that data without rebinding.
*
* @param position Position to obtain a view for
* @return A view representing the data at <code>position</code> from <code>adapter</code>
*/
public View getViewForPosition(int position) {
return getViewForPosition(position, false);
}
View getViewForPosition(int position, boolean dryRun) {
if (position < 0 || position >= mState.getItemCount()) {
throw new IndexOutOfBoundsException("Invalid item position " + position
+ "(" + position + "). Item count:" + mState.getItemCount());
}
boolean fromScrap = false;
ViewHolder holder = null;
// 0) If there is a changed scrap, try to find from there
if (mState.isPreLayout()) {
holder = getChangedScrapViewForPosition(position);
fromScrap = holder != null;
}
// 1) Find from scrap by position
if (holder == null) {
holder = getScrapViewForPosition(position, INVALID_TYPE, dryRun);
if (holder != null) {
if (!validateViewHolderForOffsetPosition(holder)) {
// recycle this scrap
if (!dryRun) {
// we would like to recycle this but need to make sure it is not used by
// animation logic etc.
holder.addFlags(ViewHolder.FLAG_INVALID);
if (holder.isScrap()) {
removeDetachedView(holder.itemView, false);
holder.unScrap();
} else if (holder.wasReturnedFromScrap()) {
holder.clearReturnedFromScrapFlag();
}
recycleViewHolderInternal(holder);
}
holder = null;
} else {
fromScrap = true;
}
}
}
if (holder == null) {
final int offsetPosition = mAdapterHelper.findPositionOffset(position);
if (offsetPosition < 0 || offsetPosition >= mAdapter.getItemCount()) {
throw new IndexOutOfBoundsException("Inconsistency detected. Invalid item "
+ "position " + position + "(offset:" + offsetPosition + ")."
+ "state:" + mState.getItemCount());
}
final int type = mAdapter.getItemViewType(offsetPosition);
// 2) Find from scrap via stable ids, if exists
if (mAdapter.hasStableIds()) {
holder = getScrapViewForId(mAdapter.getItemId(offsetPosition), type, dryRun);
if (holder != null) {
// update position
holder.mPosition = offsetPosition;
fromScrap = true;
}
}
if (holder == null && mViewCacheExtension != null) {
// We are NOT sending the offsetPosition because LayoutManager does not
// know it.
final View view = mViewCacheExtension
.getViewForPositionAndType(this, position, type);
if (view != null) {
holder = getChildViewHolder(view);
if (holder == null) {
throw new IllegalArgumentException("getViewForPositionAndType returned"
+ " a view which does not have a ViewHolder");
} else if (holder.shouldIgnore()) {
throw new IllegalArgumentException("getViewForPositionAndType returned"
+ " a view that is ignored. You must call stopIgnoring before"
+ " returning this view.");
}
}
}
if (holder == null) { // fallback to recycler
// try recycler.
// Head to the shared pool.
if (DEBUG) {
Log.d(TAG, "getViewForPosition(" + position + ") fetching from shared "
+ "pool");
}
holder = getRecycledViewPool()
.getRecycledView(mAdapter.getItemViewType(offsetPosition));
if (holder != null) {
holder.resetInternal();
if (FORCE_INVALIDATE_DISPLAY_LIST) {
invalidateDisplayListInt(holder);
}
}
}
if (holder == null) {
holder = mAdapter.createViewHolder(RecyclerView.this,
mAdapter.getItemViewType(offsetPosition));
if (DEBUG) {
Log.d(TAG, "getViewForPosition created new ViewHolder");
}
}
}
boolean bound = false;
if (mState.isPreLayout() && holder.isBound()) {
// do not update unless we absolutely have to.
holder.mPreLayoutPosition = position;
} else if (!holder.isBound() || holder.needsUpdate() || holder.isInvalid()) {
if (DEBUG && holder.isRemoved()) {
throw new IllegalStateException("Removed holder should be bound and it should"
+ " come here only in pre-layout. Holder: " + holder);
}
final int offsetPosition = mAdapterHelper.findPositionOffset(position);
mAdapter.bindViewHolder(holder, offsetPosition);
attachAccessibilityDelegate(holder.itemView);
bound = true;
if (mState.isPreLayout()) {
holder.mPreLayoutPosition = position;
}
}
final ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();
final LayoutParams rvLayoutParams;
if (lp == null) {
rvLayoutParams = (LayoutParams) generateDefaultLayoutParams();
holder.itemView.setLayoutParams(rvLayoutParams);
} else if (!checkLayoutParams(lp)) {
rvLayoutParams = (LayoutParams) generateLayoutParams(lp);
holder.itemView.setLayoutParams(rvLayoutParams);
} else {
rvLayoutParams = (LayoutParams) lp;
}
rvLayoutParams.mViewHolder = holder;
rvLayoutParams.mPendingInvalidate = fromScrap && bound;
return holder.itemView;
}
private void attachAccessibilityDelegate(View itemView) {
if (mAccessibilityManager != null && mAccessibilityManager.isEnabled()) {
if (ViewCompat.getImportantForAccessibility(itemView) ==
ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_AUTO) {
ViewCompat.setImportantForAccessibility(itemView,
ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_YES);
}
if (!ViewCompat.hasAccessibilityDelegate(itemView)) {
ViewCompat.setAccessibilityDelegate(itemView,
mAccessibilityDelegate.getItemDelegate());
}
}
}
private void invalidateDisplayListInt(ViewHolder holder) {
if (holder.itemView instanceof ViewGroup) {
invalidateDisplayListInt((ViewGroup) holder.itemView, false);
}
}
private void invalidateDisplayListInt(ViewGroup viewGroup, boolean invalidateThis) {
for (int i = viewGroup.getChildCount() - 1; i >= 0; i--) {
final View view = viewGroup.getChildAt(i);
if (view instanceof ViewGroup) {
invalidateDisplayListInt((ViewGroup) view, true);
}
}
if (!invalidateThis) {
return;
}
// we need to force it to become invisible
if (viewGroup.getVisibility() == View.INVISIBLE) {
viewGroup.setVisibility(View.VISIBLE);
viewGroup.setVisibility(View.INVISIBLE);
} else {
final int visibility = viewGroup.getVisibility();
viewGroup.setVisibility(View.INVISIBLE);
viewGroup.setVisibility(visibility);
}
}
/**
* Recycle a detached view. The specified view will be added to a pool of views
* for later rebinding and reuse.
*
* <p>A view must be fully detached (removed from parent) before it may be recycled. If the
* View is scrapped, it will be removed from scrap list.</p>
*
* @param view Removed view for recycling
* @see LayoutManager#removeAndRecycleView(View, Recycler)
*/
public void recycleView(View view) {
// This public recycle method tries to make view recycle-able since layout manager
// intended to recycle this view (e.g. even if it is in scrap or change cache)
ViewHolder holder = getChildViewHolderInt(view);
if (holder.isTmpDetached()) {
removeDetachedView(view, false);
}
if (holder.isScrap()) {
holder.unScrap();
} else if (holder.wasReturnedFromScrap()){
holder.clearReturnedFromScrapFlag();
}
recycleViewHolderInternal(holder);
}
/**
* Internally, use this method instead of {@link #recycleView(android.view.View)} to
* catch potential bugs.
* @param view
*/
void recycleViewInternal(View view) {
recycleViewHolderInternal(getChildViewHolderInt(view));
}
void recycleAndClearCachedViews() {
final int count = mCachedViews.size();
for (int i = count - 1; i >= 0; i--) {
recycleCachedViewAt(i);
}
mCachedViews.clear();
}
/**
* Recycles a cached view and removes the view from the list. Views are added to cache
* if and only if they are recyclable, so this method does not check it again.
* <p>
* A small exception to this rule is when the view does not have an animator reference
* but transient state is true (due to animations created outside ItemAnimator). In that
* case, adapter may choose to recycle it. From RecyclerView's perspective, the view is
* still recyclable since Adapter wants to do so.
*
* @param cachedViewIndex The index of the view in cached views list
*/
void recycleCachedViewAt(int cachedViewIndex) {
if (DEBUG) {
Log.d(TAG, "Recycling cached view at index " + cachedViewIndex);
}
ViewHolder viewHolder = mCachedViews.get(cachedViewIndex);
if (DEBUG) {
Log.d(TAG, "CachedViewHolder to be recycled: " + viewHolder);
}
addViewHolderToRecycledViewPool(viewHolder);
mCachedViews.remove(cachedViewIndex);
}
/**
* internal implementation checks if view is scrapped or attached and throws an exception
* if so.
* Public version un-scraps before calling recycle.
*/
void recycleViewHolderInternal(ViewHolder holder) {
if (holder.isScrap() || holder.itemView.getParent() != null) {
throw new IllegalArgumentException(
"Scrapped or attached views may not be recycled. isScrap:"
+ holder.isScrap() + " isAttached:"
+ (holder.itemView.getParent() != null));
}
if (holder.isTmpDetached()) {
throw new IllegalArgumentException("Tmp detached view should be removed "
+ "from RecyclerView before it can be recycled: " + holder);
}
if (holder.shouldIgnore()) {
throw new IllegalArgumentException("Trying to recycle an ignored view holder. You"
+ " should first call stopIgnoringView(view) before calling recycle.");
}
//noinspection unchecked
final boolean forceRecycle = mAdapter != null
&& holder.doesTransientStatePreventRecycling()
&& mAdapter.onFailedToRecycleView(holder);
if (forceRecycle || holder.isRecyclable()) {
boolean cached = false;
if (!holder.isInvalid() && (mState.mInPreLayout || !holder.isRemoved()) &&
!holder.isChanged()) {
// Retire oldest cached view
final int cachedViewSize = mCachedViews.size();
if (cachedViewSize == mViewCacheMax && cachedViewSize > 0) {
recycleCachedViewAt(0);
}
if (cachedViewSize < mViewCacheMax) {
mCachedViews.add(holder);
cached = true;
}
}
if (!cached) {
addViewHolderToRecycledViewPool(holder);
}
} else if (DEBUG) {
Log.d(TAG, "trying to recycle a non-recycleable holder. Hopefully, it will "
+ "re-visit here. We are stil removing it from animation lists");
}
// even if the holder is not removed, we still call this method so that it is removed
// from view holder lists.
mState.onViewRecycled(holder);
}
void addViewHolderToRecycledViewPool(ViewHolder holder) {
ViewCompat.setAccessibilityDelegate(holder.itemView, null);
getRecycledViewPool().putRecycledView(holder);
dispatchViewRecycled(holder);
}
/**
* Used as a fast path for unscrapping and recycling a view during a bulk operation.
* The caller must call {@link #clearScrap()} when it's done to update the recycler's
* internal bookkeeping.
*/
void quickRecycleScrapView(View view) {
final ViewHolder holder = getChildViewHolderInt(view);
holder.mScrapContainer = null;
holder.clearReturnedFromScrapFlag();
recycleViewHolderInternal(holder);
}
/**
* Mark an attached view as scrap.
*
* <p>"Scrap" views are still attached to their parent RecyclerView but are eligible
* for rebinding and reuse. Requests for a view for a given position may return a
* reused or rebound scrap view instance.</p>
*
* @param view View to scrap
*/
void scrapView(View view) {
final ViewHolder holder = getChildViewHolderInt(view);
holder.setScrapContainer(this);
if (!holder.isChanged() || !supportsChangeAnimations()) {
if (holder.isInvalid() && !holder.isRemoved() && !mAdapter.hasStableIds()) {
throw new IllegalArgumentException("Called scrap view with an invalid view."
+ " Invalid views cannot be reused from scrap, they should rebound from"
+ " recycler pool.");
}
mAttachedScrap.add(holder);
} else {
if (mChangedScrap == null) {
mChangedScrap = new ArrayList<ViewHolder>();
}
mChangedScrap.add(holder);
}
}
/**
* Remove a previously scrapped view from the pool of eligible scrap.
*
* <p>This view will no longer be eligible for reuse until re-scrapped or
* until it is explicitly removed and recycled.</p>
*/
void unscrapView(ViewHolder holder) {
if (!holder.isChanged() || !supportsChangeAnimations() || mChangedScrap == null) {
mAttachedScrap.remove(holder);
} else {
mChangedScrap.remove(holder);
}
holder.mScrapContainer = null;
holder.clearReturnedFromScrapFlag();
}
int getScrapCount() {
return mAttachedScrap.size();
}
View getScrapViewAt(int index) {
return mAttachedScrap.get(index).itemView;
}
void clearScrap() {
mAttachedScrap.clear();
}
ViewHolder getChangedScrapViewForPosition(int position) {
// If pre-layout, check the changed scrap for an exact match.
final int changedScrapSize;
if (mChangedScrap == null || (changedScrapSize = mChangedScrap.size()) == 0) {
return null;
}
// find by position
for (int i = 0; i < changedScrapSize; i++) {
final ViewHolder holder = mChangedScrap.get(i);
if (!holder.wasReturnedFromScrap() && holder.getLayoutPosition() == position) {
holder.addFlags(ViewHolder.FLAG_RETURNED_FROM_SCRAP);
return holder;
}
}
// find by id
if (mAdapter.hasStableIds()) {
final int offsetPosition = mAdapterHelper.findPositionOffset(position);
if (offsetPosition > 0 && offsetPosition < mAdapter.getItemCount()) {
final long id = mAdapter.getItemId(offsetPosition);
for (int i = 0; i < changedScrapSize; i++) {
final ViewHolder holder = mChangedScrap.get(i);
if (!holder.wasReturnedFromScrap() && holder.getItemId() == id) {
holder.addFlags(ViewHolder.FLAG_RETURNED_FROM_SCRAP);
return holder;
}
}
}
}
return null;
}
/**
* Returns a scrap view for the position. If type is not INVALID_TYPE, it also checks if
* ViewHolder's type matches the provided type.
*
* @param position Item position
* @param type View type
* @param dryRun Does a dry run, finds the ViewHolder but does not remove
* @return a ViewHolder that can be re-used for this position.
*/
ViewHolder getScrapViewForPosition(int position, int type, boolean dryRun) {
final int scrapCount = mAttachedScrap.size();
// Try first for an exact, non-invalid match from scrap.
for (int i = 0; i < scrapCount; i++) {
final ViewHolder holder = mAttachedScrap.get(i);
if (!holder.wasReturnedFromScrap() && holder.getLayoutPosition() == position
&& !holder.isInvalid() && (mState.mInPreLayout || !holder.isRemoved())) {
if (type != INVALID_TYPE && holder.getItemViewType() != type) {
Log.e(TAG, "Scrap view for position " + position + " isn't dirty but has" +
" wrong view type! (found " + holder.getItemViewType() +
" but expected " + type + ")");
break;
}
holder.addFlags(ViewHolder.FLAG_RETURNED_FROM_SCRAP);
return holder;
}
}
if (!dryRun) {
View view = mChildHelper.findHiddenNonRemovedView(position, type);
if (view != null) {
// ending the animation should cause it to get recycled before we reuse it
mItemAnimator.endAnimation(getChildViewHolder(view));
}
}
// Search in our first-level recycled view cache.
final int cacheSize = mCachedViews.size();
for (int i = 0; i < cacheSize; i++) {
final ViewHolder holder = mCachedViews.get(i);
// invalid view holders may be in cache if adapter has stable ids as they can be
// retrieved via getScrapViewForId
if (!holder.isInvalid() && holder.getLayoutPosition() == position) {
if (!dryRun) {
mCachedViews.remove(i);
}
if (DEBUG) {
Log.d(TAG, "getScrapViewForPosition(" + position + ", " + type +
") found match in cache: " + holder);
}
return holder;
}
}
return null;
}
ViewHolder getScrapViewForId(long id, int type, boolean dryRun) {
// Look in our attached views first
final int count = mAttachedScrap.size();
for (int i = count - 1; i >= 0; i--) {
final ViewHolder holder = mAttachedScrap.get(i);
if (holder.getItemId() == id && !holder.wasReturnedFromScrap()) {
if (type == holder.getItemViewType()) {
holder.addFlags(ViewHolder.FLAG_RETURNED_FROM_SCRAP);
if (holder.isRemoved()) {
// this might be valid in two cases:
// > item is removed but we are in pre-layout pass
// >> do nothing. return as is. make sure we don't rebind
// > item is removed then added to another position and we are in
// post layout.
// >> remove removed and invalid flags, add update flag to rebind
// because item was invisible to us and we don't know what happened in
// between.
if (!mState.isPreLayout()) {
holder.setFlags(ViewHolder.FLAG_UPDATE, ViewHolder.FLAG_UPDATE |
ViewHolder.FLAG_INVALID | ViewHolder.FLAG_REMOVED);
}
}
return holder;
} else if (!dryRun) {
// Recycle this scrap. Type mismatch.
mAttachedScrap.remove(i);
removeDetachedView(holder.itemView, false);
quickRecycleScrapView(holder.itemView);
}
}
}
// Search the first-level cache
final int cacheSize = mCachedViews.size();
for (int i = cacheSize - 1; i >= 0; i--) {
final ViewHolder holder = mCachedViews.get(i);
if (holder.getItemId() == id) {
if (type == holder.getItemViewType()) {
if (!dryRun) {
mCachedViews.remove(i);
}
return holder;
} else if (!dryRun) {
recycleCachedViewAt(i);
}
}
}
return null;
}
void dispatchViewRecycled(ViewHolder holder) {
if (mRecyclerListener != null) {
mRecyclerListener.onViewRecycled(holder);
}
if (mAdapter != null) {
mAdapter.onViewRecycled(holder);
}
if (mState != null) {
mState.onViewRecycled(holder);
}
if (DEBUG) Log.d(TAG, "dispatchViewRecycled: " + holder);
}
void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter,
boolean compatibleWithPrevious) {
clear();
getRecycledViewPool().onAdapterChanged(oldAdapter, newAdapter, compatibleWithPrevious);
}
void offsetPositionRecordsForMove(int from, int to) {
final int start, end, inBetweenOffset;
if (from < to) {
start = from;
end = to;
inBetweenOffset = -1;
} else {
start = to;
end = from;
inBetweenOffset = 1;
}
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
if (holder == null || holder.mPosition < start || holder.mPosition > end) {
continue;
}
if (holder.mPosition == from) {
holder.offsetPosition(to - from, false);
} else {
holder.offsetPosition(inBetweenOffset, false);
}
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForMove cached child " + i + " holder " +
holder);
}
}
}
void offsetPositionRecordsForInsert(int insertedAt, int count) {
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
if (holder != null && holder.getLayoutPosition() >= insertedAt) {
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForInsert cached " + i + " holder " +
holder + " now at position " + (holder.mPosition + count));
}
holder.offsetPosition(count, true);
}
}
}
/**
* @param removedFrom Remove start index
* @param count Remove count
* @param applyToPreLayout If true, changes will affect ViewHolder's pre-layout position, if
* false, they'll be applied before the second layout pass
*/
void offsetPositionRecordsForRemove(int removedFrom, int count, boolean applyToPreLayout) {
final int removedEnd = removedFrom + count;
final int cachedCount = mCachedViews.size();
for (int i = cachedCount - 1; i >= 0; i--) {
final ViewHolder holder = mCachedViews.get(i);
if (holder != null) {
if (holder.getLayoutPosition() >= removedEnd) {
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForRemove cached " + i +
" holder " + holder + " now at position " +
(holder.mPosition - count));
}
holder.offsetPosition(-count, applyToPreLayout);
} else if (holder.getLayoutPosition() >= removedFrom) {
// Item for this view was removed. Dump it from the cache.
recycleCachedViewAt(i);
}
}
}
}
void setViewCacheExtension(ViewCacheExtension extension) {
mViewCacheExtension = extension;
}
void setRecycledViewPool(RecycledViewPool pool) {
if (mRecyclerPool != null) {
mRecyclerPool.detach();
}
mRecyclerPool = pool;
if (pool != null) {
mRecyclerPool.attach(getAdapter());
}
}
RecycledViewPool getRecycledViewPool() {
if (mRecyclerPool == null) {
mRecyclerPool = new RecycledViewPool();
}
return mRecyclerPool;
}
void viewRangeUpdate(int positionStart, int itemCount) {
final int positionEnd = positionStart + itemCount;
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
if (holder == null) {
continue;
}
final int pos = holder.getLayoutPosition();
if (pos >= positionStart && pos < positionEnd) {
holder.addFlags(ViewHolder.FLAG_UPDATE);
// cached views should not be flagged as changed because this will cause them
// to animate when they are returned from cache.
}
}
}
void setAdapterPositionsAsUnknown() {
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
if (holder != null) {
holder.addFlags(ViewHolder.FLAG_ADAPTER_POSITION_UNKNOWN);
}
}
}
void markKnownViewsInvalid() {
if (mAdapter != null && mAdapter.hasStableIds()) {
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
if (holder != null) {
holder.addFlags(ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID);
}
}
} else {
// we cannot re-use cached views in this case. Recycle them all
recycleAndClearCachedViews();
}
}
void clearOldPositions() {
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
holder.clearOldPosition();
}
final int scrapCount = mAttachedScrap.size();
for (int i = 0; i < scrapCount; i++) {
mAttachedScrap.get(i).clearOldPosition();
}
if (mChangedScrap != null) {
final int changedScrapCount = mChangedScrap.size();
for (int i = 0; i < changedScrapCount; i++) {
mChangedScrap.get(i).clearOldPosition();
}
}
}
void markItemDecorInsetsDirty() {
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
LayoutParams layoutParams = (LayoutParams) holder.itemView.getLayoutParams();
if (layoutParams != null) {
layoutParams.mInsetsDirty = true;
}
}
}
}
/**
* ViewCacheExtension is a helper class to provide an additional layer of view caching that can
* ben controlled by the developer.
* <p>
* When {@link Recycler#getViewForPosition(int)} is called, Recycler checks attached scrap and
* first level cache to find a matching View. If it cannot find a suitable View, Recycler will
* call the {@link #getViewForPositionAndType(Recycler, int, int)} before checking
* {@link RecycledViewPool}.
* <p>
* Note that, Recycler never sends Views to this method to be cached. It is developers
* responsibility to decide whether they want to keep their Views in this custom cache or let
* the default recycling policy handle it.
*/
public abstract static class ViewCacheExtension {
/**
* Returns a View that can be binded to the given Adapter position.
* <p>
* This method should <b>not</b> create a new View. Instead, it is expected to return
* an already created View that can be re-used for the given type and position.
* If the View is marked as ignored, it should first call
* {@link LayoutManager#stopIgnoringView(View)} before returning the View.
* <p>
* RecyclerView will re-bind the returned View to the position if necessary.
*
* @param recycler The Recycler that can be used to bind the View
* @param position The adapter position
* @param type The type of the View, defined by adapter
* @return A View that is bound to the given position or NULL if there is no View to re-use
* @see LayoutManager#ignoreView(View)
*/
abstract public View getViewForPositionAndType(Recycler recycler, int position, int type);
}
/**
* Base class for an Adapter
*
* <p>Adapters provide a binding from an app-specific data set to views that are displayed
* within a {@link RecyclerView}.</p>
*/
public static abstract class Adapter<VH extends ViewHolder> {
private final AdapterDataObservable mObservable = new AdapterDataObservable();
private boolean mHasStableIds = false;
/**
* Called when RecyclerView needs a new {@link ViewHolder} of the given type to represent
* an item.
* <p>
* This new ViewHolder should be constructed with a new View that can represent the items
* of the given type. You can either create a new View manually or inflate it from an XML
* layout file.
* <p>
* The new ViewHolder will be used to display items of the adapter using
* {@link #onBindViewHolder(ViewHolder, int)}. Since it will be re-used to display different
* items in the data set, it is a good idea to cache references to sub views of the View to
* avoid unnecessary {@link View#findViewById(int)} calls.
*
* @param parent The ViewGroup into which the new View will be added after it is bound to
* an adapter position.
* @param viewType The view type of the new View.
*
* @return A new ViewHolder that holds a View of the given view type.
* @see #getItemViewType(int)
* @see #onBindViewHolder(ViewHolder, int)
*/
public abstract VH onCreateViewHolder(ViewGroup parent, int viewType);
/**
* Called by RecyclerView to display the data at the specified position. This method
* should update the contents of the {@link ViewHolder#itemView} to reflect the item at
* the given position.
* <p>
* Note that unlike {@link android.widget.ListView}, RecyclerView will not call this
* method again if the position of the item changes in the data set unless the item itself
* is invalidated or the new position cannot be determined. For this reason, you should only
* use the <code>position</code> parameter while acquiring the related data item inside this
* method and should not keep a copy of it. If you need the position of an item later on
* (e.g. in a click listener), use {@link ViewHolder#getAdapterPosition()} which will have
* the updated adapter position.
*
* @param holder The ViewHolder which should be updated to represent the contents of the
* item at the given position in the data set.
* @param position The position of the item within the adapter's data set.
*/
public abstract void onBindViewHolder(VH holder, int position);
/**
* This method calls {@link #onCreateViewHolder(ViewGroup, int)} to create a new
* {@link ViewHolder} and initializes some private fields to be used by RecyclerView.
*
* @see #onCreateViewHolder(ViewGroup, int)
*/
public final VH createViewHolder(ViewGroup parent, int viewType) {
final VH holder = onCreateViewHolder(parent, viewType);
holder.mItemViewType = viewType;
return holder;
}
/**
* This method internally calls {@link #onBindViewHolder(ViewHolder, int)} to update the
* {@link ViewHolder} contents with the item at the given position and also sets up some
* private fields to be used by RecyclerView.
*
* @see #onBindViewHolder(ViewHolder, int)
*/
public final void bindViewHolder(VH holder, int position) {
holder.mPosition = position;
if (hasStableIds()) {
holder.mItemId = getItemId(position);
}
onBindViewHolder(holder, position);
holder.setFlags(ViewHolder.FLAG_BOUND,
ViewHolder.FLAG_BOUND | ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID
| ViewHolder.FLAG_ADAPTER_POSITION_UNKNOWN);
}
/**
* Return the view type of the item at <code>position</code> for the purposes
* of view recycling.
*
* <p>The default implementation of this method returns 0, making the assumption of
* a single view type for the adapter. Unlike ListView adapters, types need not
* be contiguous. Consider using id resources to uniquely identify item view types.
*
* @param position position to query
* @return integer value identifying the type of the view needed to represent the item at
* <code>position</code>. Type codes need not be contiguous.
*/
public int getItemViewType(int position) {
return 0;
}
/**
* Indicates whether each item in the data set can be represented with a unique identifier
* of type {@link java.lang.Long}.
*
* @param hasStableIds Whether items in data set have unique identifiers or not.
* @see #hasStableIds()
* @see #getItemId(int)
*/
public void setHasStableIds(boolean hasStableIds) {
if (hasObservers()) {
throw new IllegalStateException("Cannot change whether this adapter has " +
"stable IDs while the adapter has registered observers.");
}
mHasStableIds = hasStableIds;
}
/**
* Return the stable ID for the item at <code>position</code>. If {@link #hasStableIds()}
* would return false this method should return {@link #NO_ID}. The default implementation
* of this method returns {@link #NO_ID}.
*
* @param position Adapter position to query
* @return the stable ID of the item at position
*/
public long getItemId(int position) {
return NO_ID;
}
/**
* Returns the total number of items in the data set hold by the adapter.
*
* @return The total number of items in this adapter.
*/
public abstract int getItemCount();
/**
* Returns true if this adapter publishes a unique <code>long</code> value that can
* act as a key for the item at a given position in the data set. If that item is relocated
* in the data set, the ID returned for that item should be the same.
*
* @return true if this adapter's items have stable IDs
*/
public final boolean hasStableIds() {
return mHasStableIds;
}
/**
* Called when a view created by this adapter has been recycled.
*
* <p>A view is recycled when a {@link LayoutManager} decides that it no longer
* needs to be attached to its parent {@link RecyclerView}. This can be because it has
* fallen out of visibility or a set of cached views represented by views still
* attached to the parent RecyclerView. If an item view has large or expensive data
* bound to it such as large bitmaps, this may be a good place to release those
* resources.</p>
*
* @param holder The ViewHolder for the view being recycled
*/
public void onViewRecycled(VH holder) {
}
/**
* Called by the RecyclerView if a ViewHolder created by this Adapter cannot be recycled
* due to its transient state. Upon receiving this callback, Adapter can clear the
* animation(s) that effect the View's transient state and return <code>true</code> so that
* the View can be recycled. Keep in mind that the View in question is already removed from
* the RecyclerView.
* <p>
* In some cases, it is acceptable to recycle a View although it has transient state. Most
* of the time, this is a case where the transient state will be cleared in
* {@link #onBindViewHolder(ViewHolder, int)} call when View is rebound to a new position.
* For this reason, RecyclerView leaves the decision to the Adapter and uses the return
* value of this method to decide whether the View should be recycled or not.
* <p>
* Note that when all animations are created by {@link RecyclerView.ItemAnimator}, you
* should never receive this callback because RecyclerView keeps those Views as children
* until their animations are complete. This callback is useful when children of the item
* views create animations which may not be easy to implement using an {@link ItemAnimator}.
* <p>
* You should <em>never</em> fix this issue by calling
* <code>holder.itemView.setHasTransientState(false);</code> unless you've previously called
* <code>holder.itemView.setHasTransientState(true);</code>. Each
* <code>View.setHasTransientState(true)</code> call must be matched by a
* <code>View.setHasTransientState(false)</code> call, otherwise, the state of the View
* may become inconsistent. You should always prefer to end or cancel animations that are
* triggering the transient state instead of handling it manually.
*
* @param holder The ViewHolder containing the View that could not be recycled due to its
* transient state.
* @return True if the View should be recycled, false otherwise. Note that if this method
* returns <code>true</code>, RecyclerView <em>will ignore</em> the transient state of
* the View and recycle it regardless. If this method returns <code>false</code>,
* RecyclerView will check the View's transient state again before giving a final decision.
* Default implementation returns false.
*/
public boolean onFailedToRecycleView(VH holder) {
return false;
}
/**
* Called when a view created by this adapter has been attached to a window.
*
* <p>This can be used as a reasonable signal that the view is about to be seen
* by the user. If the adapter previously freed any resources in
* {@link #onViewDetachedFromWindow(RecyclerView.ViewHolder) onViewDetachedFromWindow}
* those resources should be restored here.</p>
*
* @param holder Holder of the view being attached
*/
public void onViewAttachedToWindow(VH holder) {
}
/**
* Called when a view created by this adapter has been detached from its window.
*
* <p>Becoming detached from the window is not necessarily a permanent condition;
* the consumer of an Adapter's views may choose to cache views offscreen while they
* are not visible, attaching an detaching them as appropriate.</p>
*
* @param holder Holder of the view being detached
*/
public void onViewDetachedFromWindow(VH holder) {
}
/**
* Returns true if one or more observers are attached to this adapter.
*
* @return true if this adapter has observers
*/
public final boolean hasObservers() {
return mObservable.hasObservers();
}
/**
* Register a new observer to listen for data changes.
*
* <p>The adapter may publish a variety of events describing specific changes.
* Not all adapters may support all change types and some may fall back to a generic
* {@link android.support.v7.widget.RecyclerView.AdapterDataObserver#onChanged()
* "something changed"} event if more specific data is not available.</p>
*
* <p>Components registering observers with an adapter are responsible for
* {@link #unregisterAdapterDataObserver(RecyclerView.AdapterDataObserver)
* unregistering} those observers when finished.</p>
*
* @param observer Observer to register
*
* @see #unregisterAdapterDataObserver(RecyclerView.AdapterDataObserver)
*/
public void registerAdapterDataObserver(AdapterDataObserver observer) {
mObservable.registerObserver(observer);
}
/**
* Unregister an observer currently listening for data changes.
*
* <p>The unregistered observer will no longer receive events about changes
* to the adapter.</p>
*
* @param observer Observer to unregister
*
* @see #registerAdapterDataObserver(RecyclerView.AdapterDataObserver)
*/
public void unregisterAdapterDataObserver(AdapterDataObserver observer) {
mObservable.unregisterObserver(observer);
}
/**
* Called by RecyclerView when it starts observing this Adapter.
* <p>
* Keep in mind that same adapter may be observed by multiple RecyclerViews.
*
* @param recyclerView The RecyclerView instance which started observing this adapter.
* @see #onDetachedFromRecyclerView(RecyclerView)
*/
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
}
/**
* Called by RecyclerView when it stops observing this Adapter.
*
* @param recyclerView The RecyclerView instance which stopped observing this adapter.
* @see #onAttachedToRecyclerView(RecyclerView)
*/
public void onDetachedFromRecyclerView(RecyclerView recyclerView) {
}
/**
* Notify any registered observers that the data set has changed.
*
* <p>There are two different classes of data change events, item changes and structural
* changes. Item changes are when a single item has its data updated but no positional
* changes have occurred. Structural changes are when items are inserted, removed or moved
* within the data set.</p>
*
* <p>This event does not specify what about the data set has changed, forcing
* any observers to assume that all existing items and structure may no longer be valid.
* LayoutManagers will be forced to fully rebind and relayout all visible views.</p>
*
* <p><code>RecyclerView</code> will attempt to synthesize visible structural change events
* for adapters that report that they have {@link #hasStableIds() stable IDs} when
* this method is used. This can help for the purposes of animation and visual
* object persistence but individual item views will still need to be rebound
* and relaid out.</p>
*
* <p>If you are writing an adapter it will always be more efficient to use the more
* specific change events if you can. Rely on <code>notifyDataSetChanged()</code>
* as a last resort.</p>
*
* @see #notifyItemChanged(int)
* @see #notifyItemInserted(int)
* @see #notifyItemRemoved(int)
* @see #notifyItemRangeChanged(int, int)
* @see #notifyItemRangeInserted(int, int)
* @see #notifyItemRangeRemoved(int, int)
*/
public final void notifyDataSetChanged() {
mObservable.notifyChanged();
}
/**
* Notify any registered observers that the item at <code>position</code> has changed.
*
* <p>This is an item change event, not a structural change event. It indicates that any
* reflection of the data at <code>position</code> is out of date and should be updated.
* The item at <code>position</code> retains the same identity.</p>
*
* @param position Position of the item that has changed
*
* @see #notifyItemRangeChanged(int, int)
*/
public final void notifyItemChanged(int position) {
mObservable.notifyItemRangeChanged(position, 1);
}
/**
* Notify any registered observers that the <code>itemCount</code> items starting at
* position <code>positionStart</code> have changed.
*
* <p>This is an item change event, not a structural change event. It indicates that
* any reflection of the data in the given position range is out of date and should
* be updated. The items in the given range retain the same identity.</p>
*
* @param positionStart Position of the first item that has changed
* @param itemCount Number of items that have changed
*
* @see #notifyItemChanged(int)
*/
public final void notifyItemRangeChanged(int positionStart, int itemCount) {
mObservable.notifyItemRangeChanged(positionStart, itemCount);
}
/**
* Notify any registered observers that the item reflected at <code>position</code>
* has been newly inserted. The item previously at <code>position</code> is now at
* position <code>position + 1</code>.
*
* <p>This is a structural change event. Representations of other existing items in the
* data set are still considered up to date and will not be rebound, though their
* positions may be altered.</p>
*
* @param position Position of the newly inserted item in the data set
*
* @see #notifyItemRangeInserted(int, int)
*/
public final void notifyItemInserted(int position) {
mObservable.notifyItemRangeInserted(position, 1);
}
/**
* Notify any registered observers that the item reflected at <code>fromPosition</code>
* has been moved to <code>toPosition</code>.
*
* <p>This is a structural change event. Representations of other existing items in the
* data set are still considered up to date and will not be rebound, though their
* positions may be altered.</p>
*
* @param fromPosition Previous position of the item.
* @param toPosition New position of the item.
*/
public final void notifyItemMoved(int fromPosition, int toPosition) {
mObservable.notifyItemMoved(fromPosition, toPosition);
}
/**
* Notify any registered observers that the currently reflected <code>itemCount</code>
* items starting at <code>positionStart</code> have been newly inserted. The items
* previously located at <code>positionStart</code> and beyond can now be found starting
* at position <code>positionStart + itemCount</code>.
*
* <p>This is a structural change event. Representations of other existing items in the
* data set are still considered up to date and will not be rebound, though their positions
* may be altered.</p>
*
* @param positionStart Position of the first item that was inserted
* @param itemCount Number of items inserted
*
* @see #notifyItemInserted(int)
*/
public final void notifyItemRangeInserted(int positionStart, int itemCount) {
mObservable.notifyItemRangeInserted(positionStart, itemCount);
}
/**
* Notify any registered observers that the item previously located at <code>position</code>
* has been removed from the data set. The items previously located at and after
* <code>position</code> may now be found at <code>oldPosition - 1</code>.
*
* <p>This is a structural change event. Representations of other existing items in the
* data set are still considered up to date and will not be rebound, though their positions
* may be altered.</p>
*
* @param position Position of the item that has now been removed
*
* @see #notifyItemRangeRemoved(int, int)
*/
public final void notifyItemRemoved(int position) {
mObservable.notifyItemRangeRemoved(position, 1);
}
/**
* Notify any registered observers that the <code>itemCount</code> items previously
* located at <code>positionStart</code> have been removed from the data set. The items
* previously located at and after <code>positionStart + itemCount</code> may now be found
* at <code>oldPosition - itemCount</code>.
*
* <p>This is a structural change event. Representations of other existing items in the data
* set are still considered up to date and will not be rebound, though their positions
* may be altered.</p>
*
* @param positionStart Previous position of the first item that was removed
* @param itemCount Number of items removed from the data set
*/
public final void notifyItemRangeRemoved(int positionStart, int itemCount) {
mObservable.notifyItemRangeRemoved(positionStart, itemCount);
}
}
private void dispatchChildDetached(View child) {
if (mAdapter != null) {
mAdapter.onViewDetachedFromWindow(getChildViewHolderInt(child));
}
onChildDetachedFromWindow(child);
}
private void dispatchChildAttached(View child) {
if (mAdapter != null) {
mAdapter.onViewAttachedToWindow(getChildViewHolderInt(child));
}
onChildAttachedToWindow(child);
}
/**
* A <code>LayoutManager</code> is responsible for measuring and positioning item views
* within a <code>RecyclerView</code> as well as determining the policy for when to recycle
* item views that are no longer visible to the user. By changing the <code>LayoutManager</code>
* a <code>RecyclerView</code> can be used to implement a standard vertically scrolling list,
* a uniform grid, staggered grids, horizontally scrolling collections and more. Several stock
* layout managers are provided for general use.
*/
public static abstract class LayoutManager {
ChildHelper mChildHelper;
RecyclerView mRecyclerView;
@Nullable
SmoothScroller mSmoothScroller;
private boolean mRequestedSimpleAnimations = false;
void setRecyclerView(RecyclerView recyclerView) {
if (recyclerView == null) {
mRecyclerView = null;
mChildHelper = null;
} else {
mRecyclerView = recyclerView;
mChildHelper = recyclerView.mChildHelper;
}
}
/**
* Calls {@code RecyclerView#requestLayout} on the underlying RecyclerView
*/
public void requestLayout() {
if(mRecyclerView != null) {
mRecyclerView.requestLayout();
}
}
/**
* Checks if RecyclerView is in the middle of a layout or scroll and throws an
* {@link IllegalStateException} if it <b>is not</b>.
*
* @param message The message for the exception. Can be null.
* @see #assertNotInLayoutOrScroll(String)
*/
public void assertInLayoutOrScroll(String message) {
if (mRecyclerView != null) {
mRecyclerView.assertInLayoutOrScroll(message);
}
}
/**
* Checks if RecyclerView is in the middle of a layout or scroll and throws an
* {@link IllegalStateException} if it <b>is</b>.
*
* @param message The message for the exception. Can be null.
* @see #assertInLayoutOrScroll(String)
*/
public void assertNotInLayoutOrScroll(String message) {
if (mRecyclerView != null) {
mRecyclerView.assertNotInLayoutOrScroll(message);
}
}
/**
* Returns whether this LayoutManager supports automatic item animations.
* A LayoutManager wishing to support item animations should obey certain
* rules as outlined in {@link #onLayoutChildren(Recycler, State)}.
* The default return value is <code>false</code>, so subclasses of LayoutManager
* will not get predictive item animations by default.
*
* <p>Whether item animations are enabled in a RecyclerView is determined both
* by the return value from this method and the
* {@link RecyclerView#setItemAnimator(ItemAnimator) ItemAnimator} set on the
* RecyclerView itself. If the RecyclerView has a non-null ItemAnimator but this
* method returns false, then simple item animations will be enabled, in which
* views that are moving onto or off of the screen are simply faded in/out. If
* the RecyclerView has a non-null ItemAnimator and this method returns true,
* then there will be two calls to {@link #onLayoutChildren(Recycler, State)} to
* setup up the information needed to more intelligently predict where appearing
* and disappearing views should be animated from/to.</p>
*
* @return true if predictive item animations should be enabled, false otherwise
*/
public boolean supportsPredictiveItemAnimations() {
return false;
}
/**
* Called when this LayoutManager is both attached to a RecyclerView and that RecyclerView
* is attached to a window.
*
* <p>Subclass implementations should always call through to the superclass implementation.
* </p>
*
* @param view The RecyclerView this LayoutManager is bound to
*/
public void onAttachedToWindow(RecyclerView view) {
}
/**
* @deprecated
* override {@link #onDetachedFromWindow(RecyclerView, Recycler)}
*/
@Deprecated
public void onDetachedFromWindow(RecyclerView view) {
}
/**
* Called when this LayoutManager is detached from its parent RecyclerView or when
* its parent RecyclerView is detached from its window.
*
* <p>Subclass implementations should always call through to the superclass implementation.
* </p>
*
* @param view The RecyclerView this LayoutManager is bound to
* @param recycler The recycler to use if you prefer to recycle your children instead of
* keeping them around.
*/
public void onDetachedFromWindow(RecyclerView view, Recycler recycler) {
onDetachedFromWindow(view);
}
/**
* Check if the RecyclerView is configured to clip child views to its padding.
*
* @return true if this RecyclerView clips children to its padding, false otherwise
*/
public boolean getClipToPadding() {
return mRecyclerView != null && mRecyclerView.mClipToPadding;
}
/**
* Lay out all relevant child views from the given adapter.
*
* The LayoutManager is in charge of the behavior of item animations. By default,
* RecyclerView has a non-null {@link #getItemAnimator() ItemAnimator}, and simple
* item animations are enabled. This means that add/remove operations on the
* adapter will result in animations to add new or appearing items, removed or
* disappearing items, and moved items. If a LayoutManager returns false from
* {@link #supportsPredictiveItemAnimations()}, which is the default, and runs a
* normal layout operation during {@link #onLayoutChildren(Recycler, State)}, the
* RecyclerView will have enough information to run those animations in a simple
* way. For example, the default ItemAnimator, {@link DefaultItemAnimator}, will
* simple fade views in and out, whether they are actuall added/removed or whether
* they are moved on or off the screen due to other add/remove operations.
*
* <p>A LayoutManager wanting a better item animation experience, where items can be
* animated onto and off of the screen according to where the items exist when they
* are not on screen, then the LayoutManager should return true from
* {@link #supportsPredictiveItemAnimations()} and add additional logic to
* {@link #onLayoutChildren(Recycler, State)}. Supporting predictive animations
* means that {@link #onLayoutChildren(Recycler, State)} will be called twice;
* once as a "pre" layout step to determine where items would have been prior to
* a real layout, and again to do the "real" layout. In the pre-layout phase,
* items will remember their pre-layout positions to allow them to be laid out
* appropriately. Also, {@link LayoutParams#isItemRemoved() removed} items will
* be returned from the scrap to help determine correct placement of other items.
* These removed items should not be added to the child list, but should be used
* to help calculate correct positioning of other views, including views that
* were not previously onscreen (referred to as APPEARING views), but whose
* pre-layout offscreen position can be determined given the extra
* information about the pre-layout removed views.</p>
*
* <p>The second layout pass is the real layout in which only non-removed views
* will be used. The only additional requirement during this pass is, if
* {@link #supportsPredictiveItemAnimations()} returns true, to note which
* views exist in the child list prior to layout and which are not there after
* layout (referred to as DISAPPEARING views), and to position/layout those views
* appropriately, without regard to the actual bounds of the RecyclerView. This allows
* the animation system to know the location to which to animate these disappearing
* views.</p>
*
* <p>The default LayoutManager implementations for RecyclerView handle all of these
* requirements for animations already. Clients of RecyclerView can either use one
* of these layout managers directly or look at their implementations of
* onLayoutChildren() to see how they account for the APPEARING and
* DISAPPEARING views.</p>
*
* @param recycler Recycler to use for fetching potentially cached views for a
* position
* @param state Transient state of RecyclerView
*/
public void onLayoutChildren(Recycler recycler, State state) {
Log.e(TAG, "You must override onLayoutChildren(Recycler recycler, State state) ");
}
/**
* Create a default <code>LayoutParams</code> object for a child of the RecyclerView.
*
* <p>LayoutManagers will often want to use a custom <code>LayoutParams</code> type
* to store extra information specific to the layout. Client code should subclass
* {@link RecyclerView.LayoutParams} for this purpose.</p>
*
* <p><em>Important:</em> if you use your own custom <code>LayoutParams</code> type
* you must also override
* {@link #checkLayoutParams(LayoutParams)},
* {@link #generateLayoutParams(android.view.ViewGroup.LayoutParams)} and
* {@link #generateLayoutParams(android.content.Context, android.util.AttributeSet)}.</p>
*
* @return A new LayoutParams for a child view
*/
public abstract LayoutParams generateDefaultLayoutParams();
/**
* Determines the validity of the supplied LayoutParams object.
*
* <p>This should check to make sure that the object is of the correct type
* and all values are within acceptable ranges. The default implementation
* returns <code>true</code> for non-null params.</p>
*
* @param lp LayoutParams object to check
* @return true if this LayoutParams object is valid, false otherwise
*/
public boolean checkLayoutParams(LayoutParams lp) {
return lp != null;
}
/**
* Create a LayoutParams object suitable for this LayoutManager, copying relevant
* values from the supplied LayoutParams object if possible.
*
* <p><em>Important:</em> if you use your own custom <code>LayoutParams</code> type
* you must also override
* {@link #checkLayoutParams(LayoutParams)},
* {@link #generateLayoutParams(android.view.ViewGroup.LayoutParams)} and
* {@link #generateLayoutParams(android.content.Context, android.util.AttributeSet)}.</p>
*
* @param lp Source LayoutParams object to copy values from
* @return a new LayoutParams object
*/
public LayoutParams generateLayoutParams(ViewGroup.LayoutParams lp) {
if (lp instanceof LayoutParams) {
return new LayoutParams((LayoutParams) lp);
} else if (lp instanceof MarginLayoutParams) {
return new LayoutParams((MarginLayoutParams) lp);
} else {
return new LayoutParams(lp);
}
}
/**
* Create a LayoutParams object suitable for this LayoutManager from
* an inflated layout resource.
*
* <p><em>Important:</em> if you use your own custom <code>LayoutParams</code> type
* you must also override
* {@link #checkLayoutParams(LayoutParams)},
* {@link #generateLayoutParams(android.view.ViewGroup.LayoutParams)} and
* {@link #generateLayoutParams(android.content.Context, android.util.AttributeSet)}.</p>
*
* @param c Context for obtaining styled attributes
* @param attrs AttributeSet describing the supplied arguments
* @return a new LayoutParams object
*/
public LayoutParams generateLayoutParams(Context c, AttributeSet attrs) {
return new LayoutParams(c, attrs);
}
/**
* Scroll horizontally by dx pixels in screen coordinates and return the distance traveled.
* The default implementation does nothing and returns 0.
*
* @param dx distance to scroll by in pixels. X increases as scroll position
* approaches the right.
* @param recycler Recycler to use for fetching potentially cached views for a
* position
* @param state Transient state of RecyclerView
* @return The actual distance scrolled. The return value will be negative if dx was
* negative and scrolling proceeeded in that direction.
* <code>Math.abs(result)</code> may be less than dx if a boundary was reached.
*/
public int scrollHorizontallyBy(int dx, Recycler recycler, State state) {
return 0;
}
/**
* Scroll vertically by dy pixels in screen coordinates and return the distance traveled.
* The default implementation does nothing and returns 0.
*
* @param dy distance to scroll in pixels. Y increases as scroll position
* approaches the bottom.
* @param recycler Recycler to use for fetching potentially cached views for a
* position
* @param state Transient state of RecyclerView
* @return The actual distance scrolled. The return value will be negative if dy was
* negative and scrolling proceeeded in that direction.
* <code>Math.abs(result)</code> may be less than dy if a boundary was reached.
*/
public int scrollVerticallyBy(int dy, Recycler recycler, State state) {
return 0;
}
/**
* Query if horizontal scrolling is currently supported. The default implementation
* returns false.
*
* @return True if this LayoutManager can scroll the current contents horizontally
*/
public boolean canScrollHorizontally() {
return false;
}
/**
* Query if vertical scrolling is currently supported. The default implementation
* returns false.
*
* @return True if this LayoutManager can scroll the current contents vertically
*/
public boolean canScrollVertically() {
return false;
}
/**
* Scroll to the specified adapter position.
*
* Actual position of the item on the screen depends on the LayoutManager implementation.
* @param position Scroll to this adapter position.
*/
public void scrollToPosition(int position) {
if (DEBUG) {
Log.e(TAG, "You MUST implement scrollToPosition. It will soon become abstract");
}
}
/**
* <p>Smooth scroll to the specified adapter position.</p>
* <p>To support smooth scrolling, override this method, create your {@link SmoothScroller}
* instance and call {@link #startSmoothScroll(SmoothScroller)}.
* </p>
* @param recyclerView The RecyclerView to which this layout manager is attached
* @param state Current State of RecyclerView
* @param position Scroll to this adapter position.
*/
public void smoothScrollToPosition(RecyclerView recyclerView, State state,
int position) {
Log.e(TAG, "You must override smoothScrollToPosition to support smooth scrolling");
}
/**
* <p>Starts a smooth scroll using the provided SmoothScroller.</p>
* <p>Calling this method will cancel any previous smooth scroll request.</p>
* @param smoothScroller Unstance which defines how smooth scroll should be animated
*/
public void startSmoothScroll(SmoothScroller smoothScroller) {
if (mSmoothScroller != null && smoothScroller != mSmoothScroller
&& mSmoothScroller.isRunning()) {
mSmoothScroller.stop();
}
mSmoothScroller = smoothScroller;
mSmoothScroller.start(mRecyclerView, this);
}
/**
* @return true if RecycylerView is currently in the state of smooth scrolling.
*/
public boolean isSmoothScrolling() {
return mSmoothScroller != null && mSmoothScroller.isRunning();
}
/**
* Returns the resolved layout direction for this RecyclerView.
*
* @return {@link android.support.v4.view.ViewCompat#LAYOUT_DIRECTION_RTL} if the layout
* direction is RTL or returns
* {@link android.support.v4.view.ViewCompat#LAYOUT_DIRECTION_LTR} if the layout direction
* is not RTL.
*/
public int getLayoutDirection() {
return ViewCompat.getLayoutDirection(mRecyclerView);
}
/**
* Ends all animations on the view created by the {@link ItemAnimator}.
*
* @param view The View for which the animations should be ended.
* @see RecyclerView.ItemAnimator#endAnimations()
*/
public void endAnimation(View view) {
if (mRecyclerView.mItemAnimator != null) {
mRecyclerView.mItemAnimator.endAnimation(getChildViewHolderInt(view));
}
}
/**
* To be called only during {@link #onLayoutChildren(Recycler, State)} to add a view
* to the layout that is known to be going away, either because it has been
* {@link Adapter#notifyItemRemoved(int) removed} or because it is actually not in the
* visible portion of the container but is being laid out in order to inform RecyclerView
* in how to animate the item out of view.
* <p>
* Views added via this method are going to be invisible to LayoutManager after the
* dispatchLayout pass is complete. They cannot be retrieved via {@link #getChildAt(int)}
* or won't be included in {@link #getChildCount()} method.
*
* @param child View to add and then remove with animation.
*/
public void addDisappearingView(View child) {
addDisappearingView(child, -1);
}
/**
* To be called only during {@link #onLayoutChildren(Recycler, State)} to add a view
* to the layout that is known to be going away, either because it has been
* {@link Adapter#notifyItemRemoved(int) removed} or because it is actually not in the
* visible portion of the container but is being laid out in order to inform RecyclerView
* in how to animate the item out of view.
* <p>
* Views added via this method are going to be invisible to LayoutManager after the
* dispatchLayout pass is complete. They cannot be retrieved via {@link #getChildAt(int)}
* or won't be included in {@link #getChildCount()} method.
*
* @param child View to add and then remove with animation.
* @param index Index of the view.
*/
public void addDisappearingView(View child, int index) {
addViewInt(child, index, true);
}
/**
* Add a view to the currently attached RecyclerView if needed. LayoutManagers should
* use this method to add views obtained from a {@link Recycler} using
* {@link Recycler#getViewForPosition(int)}.
*
* @param child View to add
*/
public void addView(View child) {
addView(child, -1);
}
/**
* Add a view to the currently attached RecyclerView if needed. LayoutManagers should
* use this method to add views obtained from a {@link Recycler} using
* {@link Recycler#getViewForPosition(int)}.
*
* @param child View to add
* @param index Index to add child at
*/
public void addView(View child, int index) {
addViewInt(child, index, false);
}
private void addViewInt(View child, int index, boolean disappearing) {
final ViewHolder holder = getChildViewHolderInt(child);
if (disappearing || holder.isRemoved()) {
// these views will be hidden at the end of the layout pass.
mRecyclerView.addToDisappearingList(child);
} else {
// This may look like unnecessary but may happen if layout manager supports
// predictive layouts and adapter removed then re-added the same item.
// In this case, added version will be visible in the post layout (because add is
// deferred) but RV will still bind it to the same View.
// So if a View re-appears in post layout pass, remove it from disappearing list.
mRecyclerView.removeFromDisappearingList(child);
}
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
if (holder.wasReturnedFromScrap() || holder.isScrap()) {
if (holder.isScrap()) {
holder.unScrap();
} else {
holder.clearReturnedFromScrapFlag();
}
mChildHelper.attachViewToParent(child, index, child.getLayoutParams(), false);
if (DISPATCH_TEMP_DETACH) {
ViewCompat.dispatchFinishTemporaryDetach(child);
}
} else if (child.getParent() == mRecyclerView) { // it was not a scrap but a valid child
// ensure in correct position
int currentIndex = mChildHelper.indexOfChild(child);
if (index == -1) {
index = mChildHelper.getChildCount();
}
if (currentIndex == -1) {
throw new IllegalStateException("Added View has RecyclerView as parent but"
+ " view is not a real child. Unfiltered index:"
+ mRecyclerView.indexOfChild(child));
}
if (currentIndex != index) {
mRecyclerView.mLayout.moveView(currentIndex, index);
}
} else {
mChildHelper.addView(child, index, false);
lp.mInsetsDirty = true;
if (mSmoothScroller != null && mSmoothScroller.isRunning()) {
mSmoothScroller.onChildAttachedToWindow(child);
}
}
if (lp.mPendingInvalidate) {
if (DEBUG) {
Log.d(TAG, "consuming pending invalidate on child " + lp.mViewHolder);
}
holder.itemView.invalidate();
lp.mPendingInvalidate = false;
}
}
/**
* Remove a view from the currently attached RecyclerView if needed. LayoutManagers should
* use this method to completely remove a child view that is no longer needed.
* LayoutManagers should strongly consider recycling removed views using
* {@link Recycler#recycleView(android.view.View)}.
*
* @param child View to remove
*/
public void removeView(View child) {
mChildHelper.removeView(child);
}
/**
* Remove a view from the currently attached RecyclerView if needed. LayoutManagers should
* use this method to completely remove a child view that is no longer needed.
* LayoutManagers should strongly consider recycling removed views using
* {@link Recycler#recycleView(android.view.View)}.
*
* @param index Index of the child view to remove
*/
public void removeViewAt(int index) {
final View child = getChildAt(index);
if (child != null) {
mChildHelper.removeViewAt(index);
}
}
/**
* Remove all views from the currently attached RecyclerView. This will not recycle
* any of the affected views; the LayoutManager is responsible for doing so if desired.
*/
public void removeAllViews() {
// Only remove non-animating views
final int childCount = getChildCount();
for (int i = childCount - 1; i >= 0; i--) {
mChildHelper.removeViewAt(i);
}
}
/**
* Returns the adapter position of the item represented by the given View. This does not
* contain any adapter changes that might have happened after the last layout.
*
* @param view The view to query
* @return The adapter position of the item which is rendered by this View.
*/
public int getPosition(View view) {
return ((RecyclerView.LayoutParams) view.getLayoutParams()).getViewLayoutPosition();
}
/**
* Returns the View type defined by the adapter.
*
* @param view The view to query
* @return The type of the view assigned by the adapter.
*/
public int getItemViewType(View view) {
return getChildViewHolderInt(view).getItemViewType();
}
/**
* Finds the view which represents the given adapter position.
* <p>
* This method traverses each child since it has no information about child order.
* Override this method to improve performance if your LayoutManager keeps data about
* child views.
* <p>
* If a view is ignored via {@link #ignoreView(View)}, it is also ignored by this method.
*
* @param position Position of the item in adapter
* @return The child view that represents the given position or null if the position is not
* laid out
*/
public View findViewByPosition(int position) {
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
ViewHolder vh = getChildViewHolderInt(child);
if (vh == null) {
continue;
}
if (vh.getLayoutPosition() == position && !vh.shouldIgnore() &&
(mRecyclerView.mState.isPreLayout() || !vh.isRemoved())) {
return child;
}
}
return null;
}
/**
* Temporarily detach a child view.
*
* <p>LayoutManagers may want to perform a lightweight detach operation to rearrange
* views currently attached to the RecyclerView. Generally LayoutManager implementations
* will want to use {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)}
* so that the detached view may be rebound and reused.</p>
*
* <p>If a LayoutManager uses this method to detach a view, it <em>must</em>
* {@link #attachView(android.view.View, int, RecyclerView.LayoutParams) reattach}
* or {@link #removeDetachedView(android.view.View) fully remove} the detached view
* before the LayoutManager entry point method called by RecyclerView returns.</p>
*
* @param child Child to detach
*/
public void detachView(View child) {
final int ind = mChildHelper.indexOfChild(child);
if (ind >= 0) {
detachViewInternal(ind, child);
}
}
/**
* Temporarily detach a child view.
*
* <p>LayoutManagers may want to perform a lightweight detach operation to rearrange
* views currently attached to the RecyclerView. Generally LayoutManager implementations
* will want to use {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)}
* so that the detached view may be rebound and reused.</p>
*
* <p>If a LayoutManager uses this method to detach a view, it <em>must</em>
* {@link #attachView(android.view.View, int, RecyclerView.LayoutParams) reattach}
* or {@link #removeDetachedView(android.view.View) fully remove} the detached view
* before the LayoutManager entry point method called by RecyclerView returns.</p>
*
* @param index Index of the child to detach
*/
public void detachViewAt(int index) {
detachViewInternal(index, getChildAt(index));
}
private void detachViewInternal(int index, View view) {
if (DISPATCH_TEMP_DETACH) {
ViewCompat.dispatchStartTemporaryDetach(view);
}
mChildHelper.detachViewFromParent(index);
}
/**
* Reattach a previously {@link #detachView(android.view.View) detached} view.
* This method should not be used to reattach views that were previously
* {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} scrapped}.
*
* @param child Child to reattach
* @param index Intended child index for child
* @param lp LayoutParams for child
*/
public void attachView(View child, int index, LayoutParams lp) {
ViewHolder vh = getChildViewHolderInt(child);
if (vh.isRemoved()) {
mRecyclerView.addToDisappearingList(child);
} else {
mRecyclerView.removeFromDisappearingList(child);
}
mChildHelper.attachViewToParent(child, index, lp, vh.isRemoved());
if (DISPATCH_TEMP_DETACH) {
ViewCompat.dispatchFinishTemporaryDetach(child);
}
}
/**
* Reattach a previously {@link #detachView(android.view.View) detached} view.
* This method should not be used to reattach views that were previously
* {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} scrapped}.
*
* @param child Child to reattach
* @param index Intended child index for child
*/
public void attachView(View child, int index) {
attachView(child, index, (LayoutParams) child.getLayoutParams());
}
/**
* Reattach a previously {@link #detachView(android.view.View) detached} view.
* This method should not be used to reattach views that were previously
* {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} scrapped}.
*
* @param child Child to reattach
*/
public void attachView(View child) {
attachView(child, -1);
}
/**
* Finish removing a view that was previously temporarily
* {@link #detachView(android.view.View) detached}.
*
* @param child Detached child to remove
*/
public void removeDetachedView(View child) {
mRecyclerView.removeDetachedView(child, false);
}
/**
* Moves a View from one position to another.
*
* @param fromIndex The View's initial index
* @param toIndex The View's target index
*/
public void moveView(int fromIndex, int toIndex) {
View view = getChildAt(fromIndex);
if (view == null) {
throw new IllegalArgumentException("Cannot move a child from non-existing index:"
+ fromIndex);
}
detachViewAt(fromIndex);
attachView(view, toIndex);
}
/**
* Detach a child view and add it to a {@link Recycler Recycler's} scrap heap.
*
* <p>Scrapping a view allows it to be rebound and reused to show updated or
* different data.</p>
*
* @param child Child to detach and scrap
* @param recycler Recycler to deposit the new scrap view into
*/
public void detachAndScrapView(View child, Recycler recycler) {
int index = mChildHelper.indexOfChild(child);
scrapOrRecycleView(recycler, index, child);
}
/**
* Detach a child view and add it to a {@link Recycler Recycler's} scrap heap.
*
* <p>Scrapping a view allows it to be rebound and reused to show updated or
* different data.</p>
*
* @param index Index of child to detach and scrap
* @param recycler Recycler to deposit the new scrap view into
*/
public void detachAndScrapViewAt(int index, Recycler recycler) {
final View child = getChildAt(index);
scrapOrRecycleView(recycler, index, child);
}
/**
* Remove a child view and recycle it using the given Recycler.
*
* @param child Child to remove and recycle
* @param recycler Recycler to use to recycle child
*/
public void removeAndRecycleView(View child, Recycler recycler) {
removeView(child);
recycler.recycleView(child);
}
/**
* Remove a child view and recycle it using the given Recycler.
*
* @param index Index of child to remove and recycle
* @param recycler Recycler to use to recycle child
*/
public void removeAndRecycleViewAt(int index, Recycler recycler) {
final View view = getChildAt(index);
removeViewAt(index);
recycler.recycleView(view);
}
/**
* Return the current number of child views attached to the parent RecyclerView.
* This does not include child views that were temporarily detached and/or scrapped.
*
* @return Number of attached children
*/
public int getChildCount() {
return mChildHelper != null ? mChildHelper.getChildCount() : 0;
}
/**
* Return the child view at the given index
* @param index Index of child to return
* @return Child view at index
*/
public View getChildAt(int index) {
return mChildHelper != null ? mChildHelper.getChildAt(index) : null;
}
/**
* Return the width of the parent RecyclerView
*
* @return Width in pixels
*/
public int getWidth() {
return mRecyclerView != null ? mRecyclerView.getWidth() : 0;
}
/**
* Return the height of the parent RecyclerView
*
* @return Height in pixels
*/
public int getHeight() {
return mRecyclerView != null ? mRecyclerView.getHeight() : 0;
}
/**
* Return the left padding of the parent RecyclerView
*
* @return Padding in pixels
*/
public int getPaddingLeft() {
return mRecyclerView != null ? mRecyclerView.getPaddingLeft() : 0;
}
/**
* Return the top padding of the parent RecyclerView
*
* @return Padding in pixels
*/
public int getPaddingTop() {
return mRecyclerView != null ? mRecyclerView.getPaddingTop() : 0;
}
/**
* Return the right padding of the parent RecyclerView
*
* @return Padding in pixels
*/
public int getPaddingRight() {
return mRecyclerView != null ? mRecyclerView.getPaddingRight() : 0;
}
/**
* Return the bottom padding of the parent RecyclerView
*
* @return Padding in pixels
*/
public int getPaddingBottom() {
return mRecyclerView != null ? mRecyclerView.getPaddingBottom() : 0;
}
/**
* Return the start padding of the parent RecyclerView
*
* @return Padding in pixels
*/
public int getPaddingStart() {
return mRecyclerView != null ? ViewCompat.getPaddingStart(mRecyclerView) : 0;
}
/**
* Return the end padding of the parent RecyclerView
*
* @return Padding in pixels
*/
public int getPaddingEnd() {
return mRecyclerView != null ? ViewCompat.getPaddingEnd(mRecyclerView) : 0;
}
/**
* Returns true if the RecyclerView this LayoutManager is bound to has focus.
*
* @return True if the RecyclerView has focus, false otherwise.
* @see View#isFocused()
*/
public boolean isFocused() {
return mRecyclerView != null && mRecyclerView.isFocused();
}
/**
* Returns true if the RecyclerView this LayoutManager is bound to has or contains focus.
*
* @return true if the RecyclerView has or contains focus
* @see View#hasFocus()
*/
public boolean hasFocus() {
return mRecyclerView != null && mRecyclerView.hasFocus();
}
/**
* Returns the item View which has or contains focus.
*
* @return A direct child of RecyclerView which has focus or contains the focused child.
*/
public View getFocusedChild() {
if (mRecyclerView == null) {
return null;
}
final View focused = mRecyclerView.getFocusedChild();
if (focused == null || mChildHelper.isHidden(focused)) {
return null;
}
return focused;
}
/**
* Returns the number of items in the adapter bound to the parent RecyclerView.
* <p>
* Note that this number is not necessarily equal to {@link State#getItemCount()}. In
* methods where State is available, you should use {@link State#getItemCount()} instead.
* For more details, check the documentation for {@link State#getItemCount()}.
*
* @return The number of items in the bound adapter
* @see State#getItemCount()
*/
public int getItemCount() {
final Adapter a = mRecyclerView != null ? mRecyclerView.getAdapter() : null;
return a != null ? a.getItemCount() : 0;
}
/**
* Offset all child views attached to the parent RecyclerView by dx pixels along
* the horizontal axis.
*
* @param dx Pixels to offset by
*/
public void offsetChildrenHorizontal(int dx) {
if (mRecyclerView != null) {
mRecyclerView.offsetChildrenHorizontal(dx);
}
}
/**
* Offset all child views attached to the parent RecyclerView by dy pixels along
* the vertical axis.
*
* @param dy Pixels to offset by
*/
public void offsetChildrenVertical(int dy) {
if (mRecyclerView != null) {
mRecyclerView.offsetChildrenVertical(dy);
}
}
/**
* Flags a view so that it will not be scrapped or recycled.
* <p>
* Scope of ignoring a child is strictly restricted to position tracking, scrapping and
* recyling. Methods like {@link #removeAndRecycleAllViews(Recycler)} will ignore the child
* whereas {@link #removeAllViews()} or {@link #offsetChildrenHorizontal(int)} will not
* ignore the child.
* <p>
* Before this child can be recycled again, you have to call
* {@link #stopIgnoringView(View)}.
* <p>
* You can call this method only if your LayoutManger is in onLayout or onScroll callback.
*
* @param view View to ignore.
* @see #stopIgnoringView(View)
*/
public void ignoreView(View view) {
if (view.getParent() != mRecyclerView || mRecyclerView.indexOfChild(view) == -1) {
// checking this because calling this method on a recycled or detached view may
// cause loss of state.
throw new IllegalArgumentException("View should be fully attached to be ignored");
}
final ViewHolder vh = getChildViewHolderInt(view);
vh.addFlags(ViewHolder.FLAG_IGNORE);
mRecyclerView.mState.onViewIgnored(vh);
}
/**
* View can be scrapped and recycled again.
* <p>
* Note that calling this method removes all information in the view holder.
* <p>
* You can call this method only if your LayoutManger is in onLayout or onScroll callback.
*
* @param view View to ignore.
*/
public void stopIgnoringView(View view) {
final ViewHolder vh = getChildViewHolderInt(view);
vh.stopIgnoring();
vh.resetInternal();
vh.addFlags(ViewHolder.FLAG_INVALID);
}
/**
* Temporarily detach and scrap all currently attached child views. Views will be scrapped
* into the given Recycler. The Recycler may prefer to reuse scrap views before
* other views that were previously recycled.
*
* @param recycler Recycler to scrap views into
*/
public void detachAndScrapAttachedViews(Recycler recycler) {
final int childCount = getChildCount();
for (int i = childCount - 1; i >= 0; i--) {
final View v = getChildAt(i);
scrapOrRecycleView(recycler, i, v);
}
}
private void scrapOrRecycleView(Recycler recycler, int index, View view) {
final ViewHolder viewHolder = getChildViewHolderInt(view);
if (viewHolder.shouldIgnore()) {
if (DEBUG) {
Log.d(TAG, "ignoring view " + viewHolder);
}
return;
}
if (viewHolder.isInvalid() && !viewHolder.isRemoved() && !viewHolder.isChanged() &&
!mRecyclerView.mAdapter.hasStableIds()) {
removeViewAt(index);
recycler.recycleViewHolderInternal(viewHolder);
} else {
detachViewAt(index);
recycler.scrapView(view);
}
}
/**
* Recycles the scrapped views.
* <p>
* When a view is detached and removed, it does not trigger a ViewGroup invalidate. This is
* the expected behavior if scrapped views are used for animations. Otherwise, we need to
* call remove and invalidate RecyclerView to ensure UI update.
*
* @param recycler Recycler
*/
void removeAndRecycleScrapInt(Recycler recycler) {
final int scrapCount = recycler.getScrapCount();
for (int i = 0; i < scrapCount; i++) {
final View scrap = recycler.getScrapViewAt(i);
final ViewHolder vh = getChildViewHolderInt(scrap);
if (vh.shouldIgnore()) {
continue;
}
if (vh.isTmpDetached()) {
mRecyclerView.removeDetachedView(scrap, false);
}
recycler.quickRecycleScrapView(scrap);
}
recycler.clearScrap();
if (scrapCount > 0) {
mRecyclerView.invalidate();
}
}
/**
* Measure a child view using standard measurement policy, taking the padding
* of the parent RecyclerView and any added item decorations into account.
*
* <p>If the RecyclerView can be scrolled in either dimension the caller may
* pass 0 as the widthUsed or heightUsed parameters as they will be irrelevant.</p>
*
* @param child Child view to measure
* @param widthUsed Width in pixels currently consumed by other views, if relevant
* @param heightUsed Height in pixels currently consumed by other views, if relevant
*/
public void measureChild(View child, int widthUsed, int heightUsed) {
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
final Rect insets = mRecyclerView.getItemDecorInsetsForChild(child);
widthUsed += insets.left + insets.right;
heightUsed += insets.top + insets.bottom;
final int widthSpec = getChildMeasureSpec(getWidth(),
getPaddingLeft() + getPaddingRight() + widthUsed, lp.width,
canScrollHorizontally());
final int heightSpec = getChildMeasureSpec(getHeight(),
getPaddingTop() + getPaddingBottom() + heightUsed, lp.height,
canScrollVertically());
child.measure(widthSpec, heightSpec);
}
/**
* Measure a child view using standard measurement policy, taking the padding
* of the parent RecyclerView, any added item decorations and the child margins
* into account.
*
* <p>If the RecyclerView can be scrolled in either dimension the caller may
* pass 0 as the widthUsed or heightUsed parameters as they will be irrelevant.</p>
*
* @param child Child view to measure
* @param widthUsed Width in pixels currently consumed by other views, if relevant
* @param heightUsed Height in pixels currently consumed by other views, if relevant
*/
public void measureChildWithMargins(View child, int widthUsed, int heightUsed) {
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
final Rect insets = mRecyclerView.getItemDecorInsetsForChild(child);
widthUsed += insets.left + insets.right;
heightUsed += insets.top + insets.bottom;
final int widthSpec = getChildMeasureSpec(getWidth(),
getPaddingLeft() + getPaddingRight() +
lp.leftMargin + lp.rightMargin + widthUsed, lp.width,
canScrollHorizontally());
final int heightSpec = getChildMeasureSpec(getHeight(),
getPaddingTop() + getPaddingBottom() +
lp.topMargin + lp.bottomMargin + heightUsed, lp.height,
canScrollVertically());
child.measure(widthSpec, heightSpec);
}
/**
* Calculate a MeasureSpec value for measuring a child view in one dimension.
*
* @param parentSize Size of the parent view where the child will be placed
* @param padding Total space currently consumed by other elements of parent
* @param childDimension Desired size of the child view, or MATCH_PARENT/WRAP_CONTENT.
* Generally obtained from the child view's LayoutParams
* @param canScroll true if the parent RecyclerView can scroll in this dimension
*
* @return a MeasureSpec value for the child view
*/
public static int getChildMeasureSpec(int parentSize, int padding, int childDimension,
boolean canScroll) {
int size = Math.max(0, parentSize - padding);
int resultSize = 0;
int resultMode = 0;
if (canScroll) {
if (childDimension >= 0) {
resultSize = childDimension;
resultMode = MeasureSpec.EXACTLY;
} else {
// MATCH_PARENT can't be applied since we can scroll in this dimension, wrap
// instead using UNSPECIFIED.
resultSize = 0;
resultMode = MeasureSpec.UNSPECIFIED;
}
} else {
if (childDimension >= 0) {
resultSize = childDimension;
resultMode = MeasureSpec.EXACTLY;
} else if (childDimension == LayoutParams.FILL_PARENT) {
resultSize = size;
resultMode = MeasureSpec.EXACTLY;
} else if (childDimension == LayoutParams.WRAP_CONTENT) {
resultSize = size;
resultMode = MeasureSpec.AT_MOST;
}
}
return MeasureSpec.makeMeasureSpec(resultSize, resultMode);
}
/**
* Returns the measured width of the given child, plus the additional size of
* any insets applied by {@link ItemDecoration ItemDecorations}.
*
* @param child Child view to query
* @return child's measured width plus <code>ItemDecoration</code> insets
*
* @see View#getMeasuredWidth()
*/
public int getDecoratedMeasuredWidth(View child) {
final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets;
return child.getMeasuredWidth() + insets.left + insets.right;
}
/**
* Returns the measured height of the given child, plus the additional size of
* any insets applied by {@link ItemDecoration ItemDecorations}.
*
* @param child Child view to query
* @return child's measured height plus <code>ItemDecoration</code> insets
*
* @see View#getMeasuredHeight()
*/
public int getDecoratedMeasuredHeight(View child) {
final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets;
return child.getMeasuredHeight() + insets.top + insets.bottom;
}
/**
* Lay out the given child view within the RecyclerView using coordinates that
* include any current {@link ItemDecoration ItemDecorations}.
*
* <p>LayoutManagers should prefer working in sizes and coordinates that include
* item decoration insets whenever possible. This allows the LayoutManager to effectively
* ignore decoration insets within measurement and layout code. See the following
* methods:</p>
* <ul>
* <li>{@link #measureChild(View, int, int)}</li>
* <li>{@link #measureChildWithMargins(View, int, int)}</li>
* <li>{@link #getDecoratedLeft(View)}</li>
* <li>{@link #getDecoratedTop(View)}</li>
* <li>{@link #getDecoratedRight(View)}</li>
* <li>{@link #getDecoratedBottom(View)}</li>
* <li>{@link #getDecoratedMeasuredWidth(View)}</li>
* <li>{@link #getDecoratedMeasuredHeight(View)}</li>
* </ul>
*
* @param child Child to lay out
* @param left Left edge, with item decoration insets included
* @param top Top edge, with item decoration insets included
* @param right Right edge, with item decoration insets included
* @param bottom Bottom edge, with item decoration insets included
*
* @see View#layout(int, int, int, int)
*/
public void layoutDecorated(View child, int left, int top, int right, int bottom) {
final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets;
child.layout(left + insets.left, top + insets.top, right - insets.right,
bottom - insets.bottom);
}
/**
* Returns the left edge of the given child view within its parent, offset by any applied
* {@link ItemDecoration ItemDecorations}.
*
* @param child Child to query
* @return Child left edge with offsets applied
* @see #getLeftDecorationWidth(View)
*/
public int getDecoratedLeft(View child) {
return child.getLeft() - getLeftDecorationWidth(child);
}
/**
* Returns the top edge of the given child view within its parent, offset by any applied
* {@link ItemDecoration ItemDecorations}.
*
* @param child Child to query
* @return Child top edge with offsets applied
* @see #getTopDecorationHeight(View)
*/
public int getDecoratedTop(View child) {
return child.getTop() - getTopDecorationHeight(child);
}
/**
* Returns the right edge of the given child view within its parent, offset by any applied
* {@link ItemDecoration ItemDecorations}.
*
* @param child Child to query
* @return Child right edge with offsets applied
* @see #getRightDecorationWidth(View)
*/
public int getDecoratedRight(View child) {
return child.getRight() + getRightDecorationWidth(child);
}
/**
* Returns the bottom edge of the given child view within its parent, offset by any applied
* {@link ItemDecoration ItemDecorations}.
*
* @param child Child to query
* @return Child bottom edge with offsets applied
* @see #getBottomDecorationHeight(View)
*/
public int getDecoratedBottom(View child) {
return child.getBottom() + getBottomDecorationHeight(child);
}
/**
* Calculates the item decor insets applied to the given child and updates the provided
* Rect instance with the inset values.
* <ul>
* <li>The Rect's left is set to the total width of left decorations.</li>
* <li>The Rect's top is set to the total height of top decorations.</li>
* <li>The Rect's right is set to the total width of right decorations.</li>
* <li>The Rect's bottom is set to total height of bottom decorations.</li>
* </ul>
* <p>
* Note that item decorations are automatically calculated when one of the LayoutManager's
* measure child methods is called. If you need to measure the child with custom specs via
* {@link View#measure(int, int)}, you can use this method to get decorations.
*
* @param child The child view whose decorations should be calculated
* @param outRect The Rect to hold result values
*/
public void calculateItemDecorationsForChild(View child, Rect outRect) {
if (mRecyclerView == null) {
outRect.set(0, 0, 0, 0);
return;
}
Rect insets = mRecyclerView.getItemDecorInsetsForChild(child);
outRect.set(insets);
}
/**
* Returns the total height of item decorations applied to child's top.
* <p>
* Note that this value is not updated until the View is measured or
* {@link #calculateItemDecorationsForChild(View, Rect)} is called.
*
* @param child Child to query
* @return The total height of item decorations applied to the child's top.
* @see #getDecoratedTop(View)
* @see #calculateItemDecorationsForChild(View, Rect)
*/
public int getTopDecorationHeight(View child) {
return ((LayoutParams) child.getLayoutParams()).mDecorInsets.top;
}
/**
* Returns the total height of item decorations applied to child's bottom.
* <p>
* Note that this value is not updated until the View is measured or
* {@link #calculateItemDecorationsForChild(View, Rect)} is called.
*
* @param child Child to query
* @return The total height of item decorations applied to the child's bottom.
* @see #getDecoratedBottom(View)
* @see #calculateItemDecorationsForChild(View, Rect)
*/
public int getBottomDecorationHeight(View child) {
return ((LayoutParams) child.getLayoutParams()).mDecorInsets.bottom;
}
/**
* Returns the total width of item decorations applied to child's left.
* <p>
* Note that this value is not updated until the View is measured or
* {@link #calculateItemDecorationsForChild(View, Rect)} is called.
*
* @param child Child to query
* @return The total width of item decorations applied to the child's left.
* @see #getDecoratedLeft(View)
* @see #calculateItemDecorationsForChild(View, Rect)
*/
public int getLeftDecorationWidth(View child) {
return ((LayoutParams) child.getLayoutParams()).mDecorInsets.left;
}
/**
* Returns the total width of item decorations applied to child's right.
* <p>
* Note that this value is not updated until the View is measured or
* {@link #calculateItemDecorationsForChild(View, Rect)} is called.
*
* @param child Child to query
* @return The total width of item decorations applied to the child's right.
* @see #getDecoratedRight(View)
* @see #calculateItemDecorationsForChild(View, Rect)
*/
public int getRightDecorationWidth(View child) {
return ((LayoutParams) child.getLayoutParams()).mDecorInsets.right;
}
/**
* Called when searching for a focusable view in the given direction has failed
* for the current content of the RecyclerView.
*
* <p>This is the LayoutManager's opportunity to populate views in the given direction
* to fulfill the request if it can. The LayoutManager should attach and return
* the view to be focused. The default implementation returns null.</p>
*
* @param focused The currently focused view
* @param direction One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN},
* {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT},
* {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD}
* or 0 for not applicable
* @param recycler The recycler to use for obtaining views for currently offscreen items
* @param state Transient state of RecyclerView
* @return The chosen view to be focused
*/
public View onFocusSearchFailed(View focused, int direction, Recycler recycler,
State state) {
return null;
}
/**
* This method gives a LayoutManager an opportunity to intercept the initial focus search
* before the default behavior of {@link FocusFinder} is used. If this method returns
* null FocusFinder will attempt to find a focusable child view. If it fails
* then {@link #onFocusSearchFailed(View, int, RecyclerView.Recycler, RecyclerView.State)}
* will be called to give the LayoutManager an opportunity to add new views for items
* that did not have attached views representing them. The LayoutManager should not add
* or remove views from this method.
*
* @param focused The currently focused view
* @param direction One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN},
* {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT},
* {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD}
* @return A descendant view to focus or null to fall back to default behavior.
* The default implementation returns null.
*/
public View onInterceptFocusSearch(View focused, int direction) {
return null;
}
/**
* Called when a child of the RecyclerView wants a particular rectangle to be positioned
* onto the screen. See {@link ViewParent#requestChildRectangleOnScreen(android.view.View,
* android.graphics.Rect, boolean)} for more details.
*
* <p>The base implementation will attempt to perform a standard programmatic scroll
* to bring the given rect into view, within the padded area of the RecyclerView.</p>
*
* @param child The direct child making the request.
* @param rect The rectangle in the child's coordinates the child
* wishes to be on the screen.
* @param immediate True to forbid animated or delayed scrolling,
* false otherwise
* @return Whether the group scrolled to handle the operation
*/
public boolean requestChildRectangleOnScreen(RecyclerView parent, View child, Rect rect,
boolean immediate) {
final int parentLeft = getPaddingLeft();
final int parentTop = getPaddingTop();
final int parentRight = getWidth() - getPaddingRight();
final int parentBottom = getHeight() - getPaddingBottom();
final int childLeft = child.getLeft() + rect.left;
final int childTop = child.getTop() + rect.top;
final int childRight = childLeft + rect.width();
final int childBottom = childTop + rect.height();
final int offScreenLeft = Math.min(0, childLeft - parentLeft);
final int offScreenTop = Math.min(0, childTop - parentTop);
final int offScreenRight = Math.max(0, childRight - parentRight);
final int offScreenBottom = Math.max(0, childBottom - parentBottom);
// Favor the "start" layout direction over the end when bringing one side or the other
// of a large rect into view.
final int dx;
if (ViewCompat.getLayoutDirection(parent) == ViewCompat.LAYOUT_DIRECTION_RTL) {
dx = offScreenRight != 0 ? offScreenRight : offScreenLeft;
} else {
dx = offScreenLeft != 0 ? offScreenLeft : offScreenRight;
}
// Favor bringing the top into view over the bottom
final int dy = offScreenTop != 0 ? offScreenTop : offScreenBottom;
if (dx != 0 || dy != 0) {
if (immediate) {
parent.scrollBy(dx, dy);
} else {
parent.smoothScrollBy(dx, dy);
}
return true;
}
return false;
}
/**
* @deprecated Use {@link #onRequestChildFocus(RecyclerView, State, View, View)}
*/
@Deprecated
public boolean onRequestChildFocus(RecyclerView parent, View child, View focused) {
// eat the request if we are in the middle of a scroll or layout
return isSmoothScrolling() || parent.mRunningLayoutOrScroll;
}
/**
* Called when a descendant view of the RecyclerView requests focus.
*
* <p>A LayoutManager wishing to keep focused views aligned in a specific
* portion of the view may implement that behavior in an override of this method.</p>
*
* <p>If the LayoutManager executes different behavior that should override the default
* behavior of scrolling the focused child on screen instead of running alongside it,
* this method should return true.</p>
*
* @param parent The RecyclerView hosting this LayoutManager
* @param state Current state of RecyclerView
* @param child Direct child of the RecyclerView containing the newly focused view
* @param focused The newly focused view. This may be the same view as child or it may be
* null
* @return true if the default scroll behavior should be suppressed
*/
public boolean onRequestChildFocus(RecyclerView parent, State state, View child,
View focused) {
return onRequestChildFocus(parent, child, focused);
}
/**
* Called if the RecyclerView this LayoutManager is bound to has a different adapter set.
* The LayoutManager may use this opportunity to clear caches and configure state such
* that it can relayout appropriately with the new data and potentially new view types.
*
* <p>The default implementation removes all currently attached views.</p>
*
* @param oldAdapter The previous adapter instance. Will be null if there was previously no
* adapter.
* @param newAdapter The new adapter instance. Might be null if
* {@link #setAdapter(RecyclerView.Adapter)} is called with {@code null}.
*/
public void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter) {
}
/**
* Called to populate focusable views within the RecyclerView.
*
* <p>The LayoutManager implementation should return <code>true</code> if the default
* behavior of {@link ViewGroup#addFocusables(java.util.ArrayList, int)} should be
* suppressed.</p>
*
* <p>The default implementation returns <code>false</code> to trigger RecyclerView
* to fall back to the default ViewGroup behavior.</p>
*
* @param recyclerView The RecyclerView hosting this LayoutManager
* @param views List of output views. This method should add valid focusable views
* to this list.
* @param direction One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN},
* {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT},
* {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD}
* @param focusableMode The type of focusables to be added.
*
* @return true to suppress the default behavior, false to add default focusables after
* this method returns.
*
* @see #FOCUSABLES_ALL
* @see #FOCUSABLES_TOUCH_MODE
*/
public boolean onAddFocusables(RecyclerView recyclerView, ArrayList<View> views,
int direction, int focusableMode) {
return false;
}
/**
* Called when {@link Adapter#notifyDataSetChanged()} is triggered instead of giving
* detailed information on what has actually changed.
*
* @param recyclerView
*/
public void onItemsChanged(RecyclerView recyclerView) {
}
/**
* Called when items have been added to the adapter. The LayoutManager may choose to
* requestLayout if the inserted items would require refreshing the currently visible set
* of child views. (e.g. currently empty space would be filled by appended items, etc.)
*
* @param recyclerView
* @param positionStart
* @param itemCount
*/
public void onItemsAdded(RecyclerView recyclerView, int positionStart, int itemCount) {
}
/**
* Called when items have been removed from the adapter.
*
* @param recyclerView
* @param positionStart
* @param itemCount
*/
public void onItemsRemoved(RecyclerView recyclerView, int positionStart, int itemCount) {
}
/**
* Called when items have been changed in the adapter.
*
* @param recyclerView
* @param positionStart
* @param itemCount
*/
public void onItemsUpdated(RecyclerView recyclerView, int positionStart, int itemCount) {
}
/**
* Called when an item is moved withing the adapter.
* <p>
* Note that, an item may also change position in response to another ADD/REMOVE/MOVE
* operation. This callback is only called if and only if {@link Adapter#notifyItemMoved}
* is called.
*
* @param recyclerView
* @param from
* @param to
* @param itemCount
*/
public void onItemsMoved(RecyclerView recyclerView, int from, int to, int itemCount) {
}
/**
* <p>Override this method if you want to support scroll bars.</p>
*
* <p>Read {@link RecyclerView#computeHorizontalScrollExtent()} for details.</p>
*
* <p>Default implementation returns 0.</p>
*
* @param state Current state of RecyclerView
* @return The horizontal extent of the scrollbar's thumb
* @see RecyclerView#computeHorizontalScrollExtent()
*/
public int computeHorizontalScrollExtent(State state) {
return 0;
}
/**
* <p>Override this method if you want to support scroll bars.</p>
*
* <p>Read {@link RecyclerView#computeHorizontalScrollOffset()} for details.</p>
*
* <p>Default implementation returns 0.</p>
*
* @param state Current State of RecyclerView where you can find total item count
* @return The horizontal offset of the scrollbar's thumb
* @see RecyclerView#computeHorizontalScrollOffset()
*/
public int computeHorizontalScrollOffset(State state) {
return 0;
}
/**
* <p>Override this method if you want to support scroll bars.</p>
*
* <p>Read {@link RecyclerView#computeHorizontalScrollRange()} for details.</p>
*
* <p>Default implementation returns 0.</p>
*
* @param state Current State of RecyclerView where you can find total item count
* @return The total horizontal range represented by the vertical scrollbar
* @see RecyclerView#computeHorizontalScrollRange()
*/
public int computeHorizontalScrollRange(State state) {
return 0;
}
/**
* <p>Override this method if you want to support scroll bars.</p>
*
* <p>Read {@link RecyclerView#computeVerticalScrollExtent()} for details.</p>
*
* <p>Default implementation returns 0.</p>
*
* @param state Current state of RecyclerView
* @return The vertical extent of the scrollbar's thumb
* @see RecyclerView#computeVerticalScrollExtent()
*/
public int computeVerticalScrollExtent(State state) {
return 0;
}
/**
* <p>Override this method if you want to support scroll bars.</p>
*
* <p>Read {@link RecyclerView#computeVerticalScrollOffset()} for details.</p>
*
* <p>Default implementation returns 0.</p>
*
* @param state Current State of RecyclerView where you can find total item count
* @return The vertical offset of the scrollbar's thumb
* @see RecyclerView#computeVerticalScrollOffset()
*/
public int computeVerticalScrollOffset(State state) {
return 0;
}
/**
* <p>Override this method if you want to support scroll bars.</p>
*
* <p>Read {@link RecyclerView#computeVerticalScrollRange()} for details.</p>
*
* <p>Default implementation returns 0.</p>
*
* @param state Current State of RecyclerView where you can find total item count
* @return The total vertical range represented by the vertical scrollbar
* @see RecyclerView#computeVerticalScrollRange()
*/
public int computeVerticalScrollRange(State state) {
return 0;
}
/**
* Measure the attached RecyclerView. Implementations must call
* {@link #setMeasuredDimension(int, int)} before returning.
*
* <p>The default implementation will handle EXACTLY measurements and respect
* the minimum width and height properties of the host RecyclerView if measured
* as UNSPECIFIED. AT_MOST measurements will be treated as EXACTLY and the RecyclerView
* will consume all available space.</p>
*
* @param recycler Recycler
* @param state Transient state of RecyclerView
* @param widthSpec Width {@link android.view.View.MeasureSpec}
* @param heightSpec Height {@link android.view.View.MeasureSpec}
*/
public void onMeasure(Recycler recycler, State state, int widthSpec, int heightSpec) {
mRecyclerView.defaultOnMeasure(widthSpec, heightSpec);
}
/**
* {@link View#setMeasuredDimension(int, int) Set the measured dimensions} of the
* host RecyclerView.
*
* @param widthSize Measured width
* @param heightSize Measured height
*/
public void setMeasuredDimension(int widthSize, int heightSize) {
mRecyclerView.setMeasuredDimension(widthSize, heightSize);
}
/**
* @return The host RecyclerView's {@link View#getMinimumWidth()}
*/
public int getMinimumWidth() {
return ViewCompat.getMinimumWidth(mRecyclerView);
}
/**
* @return The host RecyclerView's {@link View#getMinimumHeight()}
*/
public int getMinimumHeight() {
return ViewCompat.getMinimumHeight(mRecyclerView);
}
/**
* <p>Called when the LayoutManager should save its state. This is a good time to save your
* scroll position, configuration and anything else that may be required to restore the same
* layout state if the LayoutManager is recreated.</p>
* <p>RecyclerView does NOT verify if the LayoutManager has changed between state save and
* restore. This will let you share information between your LayoutManagers but it is also
* your responsibility to make sure they use the same parcelable class.</p>
*
* @return Necessary information for LayoutManager to be able to restore its state
*/
public Parcelable onSaveInstanceState() {
return null;
}
public void onRestoreInstanceState(Parcelable state) {
}
void stopSmoothScroller() {
if (mSmoothScroller != null) {
mSmoothScroller.stop();
}
}
private void onSmoothScrollerStopped(SmoothScroller smoothScroller) {
if (mSmoothScroller == smoothScroller) {
mSmoothScroller = null;
}
}
/**
* RecyclerView calls this method to notify LayoutManager that scroll state has changed.
*
* @param state The new scroll state for RecyclerView
*/
public void onScrollStateChanged(int state) {
}
/**
* Removes all views and recycles them using the given recycler.
* <p>
* If you want to clean cached views as well, you should call {@link Recycler#clear()} too.
* <p>
* If a View is marked as "ignored", it is not removed nor recycled.
*
* @param recycler Recycler to use to recycle children
* @see #removeAndRecycleView(View, Recycler)
* @see #removeAndRecycleViewAt(int, Recycler)
* @see #ignoreView(View)
*/
public void removeAndRecycleAllViews(Recycler recycler) {
for (int i = getChildCount() - 1; i >= 0; i--) {
final View view = getChildAt(i);
if (!getChildViewHolderInt(view).shouldIgnore()) {
removeAndRecycleViewAt(i, recycler);
}
}
}
// called by accessibility delegate
void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfoCompat info) {
onInitializeAccessibilityNodeInfo(mRecyclerView.mRecycler, mRecyclerView.mState,
info);
}
/**
* Called by the AccessibilityDelegate when the information about the current layout should
* be populated.
* <p>
* Default implementation adds a {@link
* android.support.v4.view.accessibility.AccessibilityNodeInfoCompat.CollectionInfoCompat}.
* <p>
* You should override
* {@link #getRowCountForAccessibility(RecyclerView.Recycler, RecyclerView.State)},
* {@link #getColumnCountForAccessibility(RecyclerView.Recycler, RecyclerView.State)},
* {@link #isLayoutHierarchical(RecyclerView.Recycler, RecyclerView.State)} and
* {@link #getSelectionModeForAccessibility(RecyclerView.Recycler, RecyclerView.State)} for
* more accurate accessibility information.
*
* @param recycler The Recycler that can be used to convert view positions into adapter
* positions
* @param state The current state of RecyclerView
* @param info The info that should be filled by the LayoutManager
* @see View#onInitializeAccessibilityNodeInfo(
*android.view.accessibility.AccessibilityNodeInfo)
* @see #getRowCountForAccessibility(RecyclerView.Recycler, RecyclerView.State)
* @see #getColumnCountForAccessibility(RecyclerView.Recycler, RecyclerView.State)
* @see #isLayoutHierarchical(RecyclerView.Recycler, RecyclerView.State)
* @see #getSelectionModeForAccessibility(RecyclerView.Recycler, RecyclerView.State)
*/
public void onInitializeAccessibilityNodeInfo(Recycler recycler, State state,
AccessibilityNodeInfoCompat info) {
info.setClassName(RecyclerView.class.getName());
if (ViewCompat.canScrollVertically(mRecyclerView, -1) ||
ViewCompat.canScrollHorizontally(mRecyclerView, -1)) {
info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD);
info.setScrollable(true);
}
if (ViewCompat.canScrollVertically(mRecyclerView, 1) ||
ViewCompat.canScrollHorizontally(mRecyclerView, 1)) {
info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD);
info.setScrollable(true);
}
final AccessibilityNodeInfoCompat.CollectionInfoCompat collectionInfo
= AccessibilityNodeInfoCompat.CollectionInfoCompat
.obtain(getRowCountForAccessibility(recycler, state),
getColumnCountForAccessibility(recycler, state),
isLayoutHierarchical(recycler, state),
getSelectionModeForAccessibility(recycler, state));
info.setCollectionInfo(collectionInfo);
}
// called by accessibility delegate
public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
onInitializeAccessibilityEvent(mRecyclerView.mRecycler, mRecyclerView.mState, event);
}
/**
* Called by the accessibility delegate to initialize an accessibility event.
* <p>
* Default implementation adds item count and scroll information to the event.
*
* @param recycler The Recycler that can be used to convert view positions into adapter
* positions
* @param state The current state of RecyclerView
* @param event The event instance to initialize
* @see View#onInitializeAccessibilityEvent(android.view.accessibility.AccessibilityEvent)
*/
public void onInitializeAccessibilityEvent(Recycler recycler, State state,
AccessibilityEvent event) {
final AccessibilityRecordCompat record = AccessibilityEventCompat
.asRecord(event);
if (mRecyclerView == null || record == null) {
return;
}
record.setScrollable(ViewCompat.canScrollVertically(mRecyclerView, 1)
|| ViewCompat.canScrollVertically(mRecyclerView, -1)
|| ViewCompat.canScrollHorizontally(mRecyclerView, -1)
|| ViewCompat.canScrollHorizontally(mRecyclerView, 1));
if (mRecyclerView.mAdapter != null) {
record.setItemCount(mRecyclerView.mAdapter.getItemCount());
}
}
// called by accessibility delegate
void onInitializeAccessibilityNodeInfoForItem(View host, AccessibilityNodeInfoCompat info) {
final ViewHolder vh = getChildViewHolderInt(host);
// avoid trying to create accessibility node info for removed children
if (vh != null && !vh.isRemoved()) {
onInitializeAccessibilityNodeInfoForItem(mRecyclerView.mRecycler,
mRecyclerView.mState, host, info);
}
}
/**
* Called by the AccessibilityDelegate when the accessibility information for a specific
* item should be populated.
* <p>
* Default implementation adds basic positioning information about the item.
*
* @param recycler The Recycler that can be used to convert view positions into adapter
* positions
* @param state The current state of RecyclerView
* @param host The child for which accessibility node info should be populated
* @param info The info to fill out about the item
* @see android.widget.AbsListView#onInitializeAccessibilityNodeInfoForItem(View, int,
* android.view.accessibility.AccessibilityNodeInfo)
*/
public void onInitializeAccessibilityNodeInfoForItem(Recycler recycler, State state,
View host, AccessibilityNodeInfoCompat info) {
int rowIndexGuess = canScrollVertically() ? getPosition(host) : 0;
int columnIndexGuess = canScrollHorizontally() ? getPosition(host) : 0;
final AccessibilityNodeInfoCompat.CollectionItemInfoCompat itemInfo
= AccessibilityNodeInfoCompat.CollectionItemInfoCompat.obtain(rowIndexGuess, 1,
columnIndexGuess, 1, false, false);
info.setCollectionItemInfo(itemInfo);
}
/**
* A LayoutManager can call this method to force RecyclerView to run simple animations in
* the next layout pass, even if there is not any trigger to do so. (e.g. adapter data
* change).
* <p>
* Note that, calling this method will not guarantee that RecyclerView will run animations
* at all. For example, if there is not any {@link ItemAnimator} set, RecyclerView will
* not run any animations but will still clear this flag after the layout is complete.
*
*/
public void requestSimpleAnimationsInNextLayout() {
mRequestedSimpleAnimations = true;
}
/**
* Returns the selection mode for accessibility. Should be
* {@link AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_NONE},
* {@link AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_SINGLE} or
* {@link AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_MULTIPLE}.
* <p>
* Default implementation returns
* {@link AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_NONE}.
*
* @param recycler The Recycler that can be used to convert view positions into adapter
* positions
* @param state The current state of RecyclerView
* @return Selection mode for accessibility. Default implementation returns
* {@link AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_NONE}.
*/
public int getSelectionModeForAccessibility(Recycler recycler, State state) {
return AccessibilityNodeInfoCompat.CollectionInfoCompat.SELECTION_MODE_NONE;
}
/**
* Returns the number of rows for accessibility.
* <p>
* Default implementation returns the number of items in the adapter if LayoutManager
* supports vertical scrolling or 1 if LayoutManager does not support vertical
* scrolling.
*
* @param recycler The Recycler that can be used to convert view positions into adapter
* positions
* @param state The current state of RecyclerView
* @return The number of rows in LayoutManager for accessibility.
*/
public int getRowCountForAccessibility(Recycler recycler, State state) {
if (mRecyclerView == null || mRecyclerView.mAdapter == null) {
return 1;
}
return canScrollVertically() ? mRecyclerView.mAdapter.getItemCount() : 1;
}
/**
* Returns the number of columns for accessibility.
* <p>
* Default implementation returns the number of items in the adapter if LayoutManager
* supports horizontal scrolling or 1 if LayoutManager does not support horizontal
* scrolling.
*
* @param recycler The Recycler that can be used to convert view positions into adapter
* positions
* @param state The current state of RecyclerView
* @return The number of rows in LayoutManager for accessibility.
*/
public int getColumnCountForAccessibility(Recycler recycler, State state) {
if (mRecyclerView == null || mRecyclerView.mAdapter == null) {
return 1;
}
return canScrollHorizontally() ? mRecyclerView.mAdapter.getItemCount() : 1;
}
/**
* Returns whether layout is hierarchical or not to be used for accessibility.
* <p>
* Default implementation returns false.
*
* @param recycler The Recycler that can be used to convert view positions into adapter
* positions
* @param state The current state of RecyclerView
* @return True if layout is hierarchical.
*/
public boolean isLayoutHierarchical(Recycler recycler, State state) {
return false;
}
// called by accessibility delegate
boolean performAccessibilityAction(int action, Bundle args) {
return performAccessibilityAction(mRecyclerView.mRecycler, mRecyclerView.mState,
action, args);
}
/**
* Called by AccessibilityDelegate when an action is requested from the RecyclerView.
*
* @param recycler The Recycler that can be used to convert view positions into adapter
* positions
* @param state The current state of RecyclerView
* @param action The action to perform
* @param args Optional action arguments
* @see View#performAccessibilityAction(int, android.os.Bundle)
*/
public boolean performAccessibilityAction(Recycler recycler, State state, int action,
Bundle args) {
if (mRecyclerView == null) {
return false;
}
int vScroll = 0, hScroll = 0;
switch (action) {
case AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD:
if (ViewCompat.canScrollVertically(mRecyclerView, -1)) {
vScroll = -(getHeight() - getPaddingTop() - getPaddingBottom());
}
if (ViewCompat.canScrollHorizontally(mRecyclerView, -1)) {
hScroll = -(getWidth() - getPaddingLeft() - getPaddingRight());
}
break;
case AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD:
if (ViewCompat.canScrollVertically(mRecyclerView, 1)) {
vScroll = getHeight() - getPaddingTop() - getPaddingBottom();
}
if (ViewCompat.canScrollHorizontally(mRecyclerView, 1)) {
hScroll = getWidth() - getPaddingLeft() - getPaddingRight();
}
break;
}
if (vScroll == 0 && hScroll == 0) {
return false;
}
mRecyclerView.scrollBy(hScroll, vScroll);
return true;
}
// called by accessibility delegate
boolean performAccessibilityActionForItem(View view, int action, Bundle args) {
return performAccessibilityActionForItem(mRecyclerView.mRecycler, mRecyclerView.mState,
view, action, args);
}
/**
* Called by AccessibilityDelegate when an accessibility action is requested on one of the
* children of LayoutManager.
* <p>
* Default implementation does not do anything.
*
* @param recycler The Recycler that can be used to convert view positions into adapter
* positions
* @param state The current state of RecyclerView
* @param view The child view on which the action is performed
* @param action The action to perform
* @param args Optional action arguments
* @return true if action is handled
* @see View#performAccessibilityAction(int, android.os.Bundle)
*/
public boolean performAccessibilityActionForItem(Recycler recycler, State state, View view,
int action, Bundle args) {
return false;
}
}
private void removeFromDisappearingList(View child) {
mDisappearingViewsInLayoutPass.remove(child);
}
private void addToDisappearingList(View child) {
if (!mDisappearingViewsInLayoutPass.contains(child)) {
mDisappearingViewsInLayoutPass.add(child);
}
}
/**
* An ItemDecoration allows the application to add a special drawing and layout offset
* to specific item views from the adapter's data set. This can be useful for drawing dividers
* between items, highlights, visual grouping boundaries and more.
*
* <p>All ItemDecorations are drawn in the order they were added, before the item
* views (in {@link ItemDecoration#onDraw(Canvas, RecyclerView, RecyclerView.State) onDraw()}
* and after the items (in {@link ItemDecoration#onDrawOver(Canvas, RecyclerView,
* RecyclerView.State)}.</p>
*/
public static abstract class ItemDecoration {
/**
* Draw any appropriate decorations into the Canvas supplied to the RecyclerView.
* Any content drawn by this method will be drawn before the item views are drawn,
* and will thus appear underneath the views.
*
* @param c Canvas to draw into
* @param parent RecyclerView this ItemDecoration is drawing into
* @param state The current state of RecyclerView
*/
public void onDraw(Canvas c, RecyclerView parent, State state) {
onDraw(c, parent);
}
/**
* @deprecated
* Override {@link #onDraw(Canvas, RecyclerView, RecyclerView.State)}
*/
@Deprecated
public void onDraw(Canvas c, RecyclerView parent) {
}
/**
* Draw any appropriate decorations into the Canvas supplied to the RecyclerView.
* Any content drawn by this method will be drawn after the item views are drawn
* and will thus appear over the views.
*
* @param c Canvas to draw into
* @param parent RecyclerView this ItemDecoration is drawing into
* @param state The current state of RecyclerView.
*/
public void onDrawOver(Canvas c, RecyclerView parent, State state) {
onDrawOver(c, parent);
}
/**
* @deprecated
* Override {@link #onDrawOver(Canvas, RecyclerView, RecyclerView.State)}
*/
@Deprecated
public void onDrawOver(Canvas c, RecyclerView parent) {
}
/**
* @deprecated
* Use {@link #getItemOffsets(Rect, View, RecyclerView, State)}
*/
@Deprecated
public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
outRect.set(0, 0, 0, 0);
}
/**
* Retrieve any offsets for the given item. Each field of <code>outRect</code> specifies
* the number of pixels that the item view should be inset by, similar to padding or margin.
* The default implementation sets the bounds of outRect to 0 and returns.
*
* <p>
* If this ItemDecoration does not affect the positioning of item views, it should set
* all four fields of <code>outRect</code> (left, top, right, bottom) to zero
* before returning.
*
* <p>
* If you need to access Adapter for additional data, you can call
* {@link RecyclerView#getChildAdapterPosition(View)} to get the adapter position of the
* View.
*
* @param outRect Rect to receive the output.
* @param view The child view to decorate
* @param parent RecyclerView this ItemDecoration is decorating
* @param state The current state of RecyclerView.
*/
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state) {
getItemOffsets(outRect, ((LayoutParams) view.getLayoutParams()).getViewLayoutPosition(),
parent);
}
}
/**
* An OnItemTouchListener allows the application to intercept touch events in progress at the
* view hierarchy level of the RecyclerView before those touch events are considered for
* RecyclerView's own scrolling behavior.
*
* <p>This can be useful for applications that wish to implement various forms of gestural
* manipulation of item views within the RecyclerView. OnItemTouchListeners may intercept
* a touch interaction already in progress even if the RecyclerView is already handling that
* gesture stream itself for the purposes of scrolling.</p>
*/
public interface OnItemTouchListener {
/**
* Silently observe and/or take over touch events sent to the RecyclerView
* before they are handled by either the RecyclerView itself or its child views.
*
* <p>The onInterceptTouchEvent methods of each attached OnItemTouchListener will be run
* in the order in which each listener was added, before any other touch processing
* by the RecyclerView itself or child views occurs.</p>
*
* @param e MotionEvent describing the touch event. All coordinates are in
* the RecyclerView's coordinate system.
* @return true if this OnItemTouchListener wishes to begin intercepting touch events, false
* to continue with the current behavior and continue observing future events in
* the gesture.
*/
public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e);
/**
* Process a touch event as part of a gesture that was claimed by returning true from
* a previous call to {@link #onInterceptTouchEvent}.
*
* @param e MotionEvent describing the touch event. All coordinates are in
* the RecyclerView's coordinate system.
*/
public void onTouchEvent(RecyclerView rv, MotionEvent e);
}
/**
* An OnScrollListener can be set on a RecyclerView to receive messages
* when a scrolling event has occurred on that RecyclerView.
*
* @see RecyclerView#setOnScrollListener(OnScrollListener)
*/
abstract static public class OnScrollListener {
/**
* Callback method to be invoked when RecyclerView's scroll state changes.
*
* @param recyclerView The RecyclerView whose scroll state has changed.
* @param newState The updated scroll state. One of {@link #SCROLL_STATE_IDLE},
* {@link #SCROLL_STATE_DRAGGING} or {@link #SCROLL_STATE_SETTLING}.
*/
public void onScrollStateChanged(RecyclerView recyclerView, int newState){}
/**
* Callback method to be invoked when the RecyclerView has been scrolled. This will be
* called after the scroll has completed.
* <p>
* This callback will also be called if visible item range changes after a layout
* calculation. In that case, dx and dy will be 0.
*
* @param recyclerView The RecyclerView which scrolled.
* @param dx The amount of horizontal scroll.
* @param dy The amount of vertical scroll.
*/
public void onScrolled(RecyclerView recyclerView, int dx, int dy){}
}
/**
* A RecyclerListener can be set on a RecyclerView to receive messages whenever
* a view is recycled.
*
* @see RecyclerView#setRecyclerListener(RecyclerListener)
*/
public interface RecyclerListener {
/**
* This method is called whenever the view in the ViewHolder is recycled.
*
* @param holder The ViewHolder containing the view that was recycled
*/
public void onViewRecycled(ViewHolder holder);
}
/**
* A ViewHolder describes an item view and metadata about its place within the RecyclerView.
*
* <p>{@link Adapter} implementations should subclass ViewHolder and add fields for caching
* potentially expensive {@link View#findViewById(int)} results.</p>
*
* <p>While {@link LayoutParams} belong to the {@link LayoutManager},
* {@link ViewHolder ViewHolders} belong to the adapter. Adapters should feel free to use
* their own custom ViewHolder implementations to store data that makes binding view contents
* easier. Implementations should assume that individual item views will hold strong references
* to <code>ViewHolder</code> objects and that <code>RecyclerView</code> instances may hold
* strong references to extra off-screen item views for caching purposes</p>
*/
public static abstract class ViewHolder {
public final View itemView;
int mPosition = NO_POSITION;
int mOldPosition = NO_POSITION;
long mItemId = NO_ID;
int mItemViewType = INVALID_TYPE;
int mPreLayoutPosition = NO_POSITION;
// The item that this holder is shadowing during an item change event/animation
ViewHolder mShadowedHolder = null;
// The item that is shadowing this holder during an item change event/animation
ViewHolder mShadowingHolder = null;
/**
* This ViewHolder has been bound to a position; mPosition, mItemId and mItemViewType
* are all valid.
*/
static final int FLAG_BOUND = 1 << 0;
/**
* The data this ViewHolder's view reflects is stale and needs to be rebound
* by the adapter. mPosition and mItemId are consistent.
*/
static final int FLAG_UPDATE = 1 << 1;
/**
* This ViewHolder's data is invalid. The identity implied by mPosition and mItemId
* are not to be trusted and may no longer match the item view type.
* This ViewHolder must be fully rebound to different data.
*/
static final int FLAG_INVALID = 1 << 2;
/**
* This ViewHolder points at data that represents an item previously removed from the
* data set. Its view may still be used for things like outgoing animations.
*/
static final int FLAG_REMOVED = 1 << 3;
/**
* This ViewHolder should not be recycled. This flag is set via setIsRecyclable()
* and is intended to keep views around during animations.
*/
static final int FLAG_NOT_RECYCLABLE = 1 << 4;
/**
* This ViewHolder is returned from scrap which means we are expecting an addView call
* for this itemView. When returned from scrap, ViewHolder stays in the scrap list until
* the end of the layout pass and then recycled by RecyclerView if it is not added back to
* the RecyclerView.
*/
static final int FLAG_RETURNED_FROM_SCRAP = 1 << 5;
/**
* This ViewHolder's contents have changed. This flag is used as an indication that
* change animations may be used, if supported by the ItemAnimator.
*/
static final int FLAG_CHANGED = 1 << 6;
/**
* This ViewHolder is fully managed by the LayoutManager. We do not scrap, recycle or remove
* it unless LayoutManager is replaced.
* It is still fully visible to the LayoutManager.
*/
static final int FLAG_IGNORE = 1 << 7;
/**
* When the View is detached form the parent, we set this flag so that we can take correct
* action when we need to remove it or add it back.
*/
static final int FLAG_TMP_DETACHED = 1 << 8;
/**
* Set when we can no longer determine the adapter position of this ViewHolder until it is
* rebound to a new position. It is different than FLAG_INVALID because FLAG_INVALID is
* set even when the type does not match. Also, FLAG_ADAPTER_POSITION_UNKNOWN is set as soon
* as adapter notification arrives vs FLAG_INVALID is set lazily before layout is
* re-calculated.
*/
static final int FLAG_ADAPTER_POSITION_UNKNOWN = 1 << 9;
private int mFlags;
private int mIsRecyclableCount = 0;
// If non-null, view is currently considered scrap and may be reused for other data by the
// scrap container.
private Recycler mScrapContainer = null;
public ViewHolder(View itemView) {
if (itemView == null) {
throw new IllegalArgumentException("itemView may not be null");
}
this.itemView = itemView;
}
void flagRemovedAndOffsetPosition(int mNewPosition, int offset, boolean applyToPreLayout) {
addFlags(ViewHolder.FLAG_REMOVED);
offsetPosition(offset, applyToPreLayout);
mPosition = mNewPosition;
}
void offsetPosition(int offset, boolean applyToPreLayout) {
if (mOldPosition == NO_POSITION) {
mOldPosition = mPosition;
}
if (mPreLayoutPosition == NO_POSITION) {
mPreLayoutPosition = mPosition;
}
if (applyToPreLayout) {
mPreLayoutPosition += offset;
}
mPosition += offset;
if (itemView.getLayoutParams() != null) {
((LayoutParams) itemView.getLayoutParams()).mInsetsDirty = true;
}
}
void clearOldPosition() {
mOldPosition = NO_POSITION;
mPreLayoutPosition = NO_POSITION;
}
void saveOldPosition() {
if (mOldPosition == NO_POSITION) {
mOldPosition = mPosition;
}
}
boolean shouldIgnore() {
return (mFlags & FLAG_IGNORE) != 0;
}
/**
* @deprecated This method is deprecated because its meaning is ambiguous due to the async
* handling of adapter updates. Please use {@link #getLayoutPosition()} or
* {@link #getAdapterPosition()} depending on your use case.
*
* @see #getLayoutPosition()
* @see #getAdapterPosition()
*/
@Deprecated
public final int getPosition() {
return mPreLayoutPosition == NO_POSITION ? mPosition : mPreLayoutPosition;
}
/**
* Returns the position of the ViewHolder in terms of the latest layout pass.
* <p>
* This position is mostly used by RecyclerView components to be consistent while
* RecyclerView lazily processes adapter updates.
* <p>
* For performance and animation reasons, RecyclerView batches all adapter updates until the
* next layout pass. This may cause mismatches between the Adapter position of the item and
* the position it had in the latest layout calculations.
* <p>
* LayoutManagers should always call this method while doing calculations based on item
* positions. All methods in {@link RecyclerView.LayoutManager}, {@link RecyclerView.State},
* {@link RecyclerView.Recycler} that receive a position expect it to be the layout position
* of the item.
* <p>
* If LayoutManager needs to call an external method that requires the adapter position of
* the item, it can use {@link #getAdapterPosition()} or
* {@link RecyclerView.Recycler#convertPreLayoutPositionToPostLayout(int)}.
*
* @return Returns the adapter position of the ViewHolder in the latest layout pass.
* @see #getAdapterPosition()
*/
public final int getLayoutPosition() {
return mPreLayoutPosition == NO_POSITION ? mPosition : mPreLayoutPosition;
}
/**
* Returns the Adapter position of the item represented by this ViewHolder.
* <p>
* Note that this might be different than the {@link #getLayoutPosition()} if there are
* pending adapter updates but a new layout pass has not happened yet.
* <p>
* RecyclerView does not handle any adapter updates until the next layout traversal. This
* may create temporary inconsistencies between what user sees on the screen and what
* adapter contents have. This inconsistency is not important since it will be less than
* 16ms but it might be a problem if you want to use ViewHolder position to access the
* adapter. Sometimes, you may need to get the exact adapter position to do
* some actions in response to user events. In that case, you should use this method which
* will calculate the Adapter position of the ViewHolder.
* <p>
* Note that if you've called {@link RecyclerView.Adapter#notifyDataSetChanged()}, until the
* next layout pass, the return value of this method will be {@link #NO_POSITION}.
*
* @return The adapter position of the item if it still exists in the adapter.
* {@link RecyclerView#NO_POSITION} if item has been removed from the adapter,
* {@link RecyclerView.Adapter#notifyDataSetChanged()} has been called after the last
* layout pass or the ViewHolder has been removed from the RecyclerView.
*/
public final int getAdapterPosition() {
final ViewParent parent = itemView.getParent();
if (!(parent instanceof RecyclerView)) {
return -1;
}
final RecyclerView rv = (RecyclerView) parent;
return rv.getAdapterPositionFor(this);
}
/**
* When LayoutManager supports animations, RecyclerView tracks 3 positions for ViewHolders
* to perform animations.
* <p>
* If a ViewHolder was laid out in the previous onLayout call, old position will keep its
* adapter index in the previous layout.
*
* @return The previous adapter index of the Item represented by this ViewHolder or
* {@link #NO_POSITION} if old position does not exists or cleared (pre-layout is
* complete).
*/
public final int getOldPosition() {
return mOldPosition;
}
/**
* Returns The itemId represented by this ViewHolder.
*
* @return The the item's id if adapter has stable ids, {@link RecyclerView#NO_ID}
* otherwise
*/
public final long getItemId() {
return mItemId;
}
/**
* @return The view type of this ViewHolder.
*/
public final int getItemViewType() {
return mItemViewType;
}
boolean isScrap() {
return mScrapContainer != null;
}
void unScrap() {
mScrapContainer.unscrapView(this);
}
boolean wasReturnedFromScrap() {
return (mFlags & FLAG_RETURNED_FROM_SCRAP) != 0;
}
void clearReturnedFromScrapFlag() {
mFlags = mFlags & ~FLAG_RETURNED_FROM_SCRAP;
}
void clearTmpDetachFlag() {
mFlags = mFlags & ~FLAG_TMP_DETACHED;
}
void stopIgnoring() {
mFlags = mFlags & ~FLAG_IGNORE;
}
void setScrapContainer(Recycler recycler) {
mScrapContainer = recycler;
}
boolean isInvalid() {
return (mFlags & FLAG_INVALID) != 0;
}
boolean needsUpdate() {
return (mFlags & FLAG_UPDATE) != 0;
}
boolean isChanged() {
return (mFlags & FLAG_CHANGED) != 0;
}
boolean isBound() {
return (mFlags & FLAG_BOUND) != 0;
}
boolean isRemoved() {
return (mFlags & FLAG_REMOVED) != 0;
}
boolean hasAnyOfTheFlags(int flags) {
return (mFlags & flags) != 0;
}
boolean isTmpDetached() {
return (mFlags & FLAG_TMP_DETACHED) != 0;
}
boolean isAdapterPositionUnknown() {
return (mFlags & FLAG_ADAPTER_POSITION_UNKNOWN) != 0;
}
void setFlags(int flags, int mask) {
mFlags = (mFlags & ~mask) | (flags & mask);
}
void addFlags(int flags) {
mFlags |= flags;
}
void resetInternal() {
mFlags = 0;
mPosition = NO_POSITION;
mOldPosition = NO_POSITION;
mItemId = NO_ID;
mPreLayoutPosition = NO_POSITION;
mIsRecyclableCount = 0;
mShadowedHolder = null;
mShadowingHolder = null;
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder("ViewHolder{" +
Integer.toHexString(hashCode()) + " position=" + mPosition + " id=" + mItemId +
", oldPos=" + mOldPosition + ", pLpos:" + mPreLayoutPosition);
if (isScrap()) sb.append(" scrap");
if (isInvalid()) sb.append(" invalid");
if (!isBound()) sb.append(" unbound");
if (needsUpdate()) sb.append(" update");
if (isRemoved()) sb.append(" removed");
if (shouldIgnore()) sb.append(" ignored");
if (isChanged()) sb.append(" changed");
if (isTmpDetached()) sb.append(" tmpDetached");
if (!isRecyclable()) sb.append(" not recyclable(" + mIsRecyclableCount + ")");
if (!isAdapterPositionUnknown()) sb.append("undefined adapter position");
if (itemView.getParent() == null) sb.append(" no parent");
sb.append("}");
return sb.toString();
}
/**
* Informs the recycler whether this item can be recycled. Views which are not
* recyclable will not be reused for other items until setIsRecyclable() is
* later set to true. Calls to setIsRecyclable() should always be paired (one
* call to setIsRecyclabe(false) should always be matched with a later call to
* setIsRecyclable(true)). Pairs of calls may be nested, as the state is internally
* reference-counted.
*
* @param recyclable Whether this item is available to be recycled. Default value
* is true.
*/
public final void setIsRecyclable(boolean recyclable) {
mIsRecyclableCount = recyclable ? mIsRecyclableCount - 1 : mIsRecyclableCount + 1;
if (mIsRecyclableCount < 0) {
mIsRecyclableCount = 0;
if (DEBUG) {
throw new RuntimeException("isRecyclable decremented below 0: " +
"unmatched pair of setIsRecyable() calls for " + this);
}
Log.e(VIEW_LOG_TAG, "isRecyclable decremented below 0: " +
"unmatched pair of setIsRecyable() calls for " + this);
} else if (!recyclable && mIsRecyclableCount == 1) {
mFlags |= FLAG_NOT_RECYCLABLE;
} else if (recyclable && mIsRecyclableCount == 0) {
mFlags &= ~FLAG_NOT_RECYCLABLE;
}
if (DEBUG) {
Log.d(TAG, "setIsRecyclable val:" + recyclable + ":" + this);
}
}
/**
* @see {@link #setIsRecyclable(boolean)}
*
* @return true if this item is available to be recycled, false otherwise.
*/
public final boolean isRecyclable() {
return (mFlags & FLAG_NOT_RECYCLABLE) == 0 &&
!ViewCompat.hasTransientState(itemView);
}
/**
* Returns whether we have animations referring to this view holder or not.
* This is similar to isRecyclable flag but does not check transient state.
*/
private boolean shouldBeKeptAsChild() {
return (mFlags & FLAG_NOT_RECYCLABLE) != 0;
}
/**
* @return True if ViewHolder is not refenrenced by RecyclerView animations but has
* transient state which will prevent it from being recycled.
*/
private boolean doesTransientStatePreventRecycling() {
return (mFlags & FLAG_NOT_RECYCLABLE) == 0 && ViewCompat.hasTransientState(itemView);
}
}
private int getAdapterPositionFor(ViewHolder viewHolder) {
if (viewHolder.hasAnyOfTheFlags(
ViewHolder.FLAG_REMOVED | ViewHolder.FLAG_ADAPTER_POSITION_UNKNOWN)) {
return RecyclerView.NO_POSITION;
}
return mAdapterHelper.applyPendingUpdatesToPosition(viewHolder.mPosition);
}
/**
* {@link android.view.ViewGroup.MarginLayoutParams LayoutParams} subclass for children of
* {@link RecyclerView}. Custom {@link LayoutManager layout managers} are encouraged
* to create their own subclass of this <code>LayoutParams</code> class
* to store any additional required per-child view metadata about the layout.
*/
public static class LayoutParams extends android.view.ViewGroup.MarginLayoutParams {
ViewHolder mViewHolder;
final Rect mDecorInsets = new Rect();
boolean mInsetsDirty = true;
// Flag is set to true if the view is bound while it is detached from RV.
// In this case, we need to manually call invalidate after view is added to guarantee that
// invalidation is populated through the View hierarchy
boolean mPendingInvalidate = false;
public LayoutParams(Context c, AttributeSet attrs) {
super(c, attrs);
}
public LayoutParams(int width, int height) {
super(width, height);
}
public LayoutParams(MarginLayoutParams source) {
super(source);
}
public LayoutParams(ViewGroup.LayoutParams source) {
super(source);
}
public LayoutParams(LayoutParams source) {
super((ViewGroup.LayoutParams) source);
}
/**
* Returns true if the view this LayoutParams is attached to needs to have its content
* updated from the corresponding adapter.
*
* @return true if the view should have its content updated
*/
public boolean viewNeedsUpdate() {
return mViewHolder.needsUpdate();
}
/**
* Returns true if the view this LayoutParams is attached to is now representing
* potentially invalid data. A LayoutManager should scrap/recycle it.
*
* @return true if the view is invalid
*/
public boolean isViewInvalid() {
return mViewHolder.isInvalid();
}
/**
* Returns true if the adapter data item corresponding to the view this LayoutParams
* is attached to has been removed from the data set. A LayoutManager may choose to
* treat it differently in order to animate its outgoing or disappearing state.
*
* @return true if the item the view corresponds to was removed from the data set
*/
public boolean isItemRemoved() {
return mViewHolder.isRemoved();
}
/**
* Returns true if the adapter data item corresponding to the view this LayoutParams
* is attached to has been changed in the data set. A LayoutManager may choose to
* treat it differently in order to animate its changing state.
*
* @return true if the item the view corresponds to was changed in the data set
*/
public boolean isItemChanged() {
return mViewHolder.isChanged();
}
/**
* @deprecated use {@link #getViewLayoutPosition()} or {@link #getViewAdapterPosition()}
*/
public int getViewPosition() {
return mViewHolder.getPosition();
}
/**
* Returns the adapter position that the view this LayoutParams is attached to corresponds
* to as of latest layout calculation.
*
* @return the adapter position this view as of latest layout pass
*/
public int getViewLayoutPosition() {
return mViewHolder.getLayoutPosition();
}
/**
* Returns the up-to-date adapter position that the view this LayoutParams is attached to
* corresponds to.
*
* @return the up-to-date adapter position this view. It may return
* {@link RecyclerView#NO_POSITION} if item represented by this View has been removed or
* its up-to-date position cannot be calculated.
*/
public int getViewAdapterPosition() {
return mViewHolder.getAdapterPosition();
}
}
/**
* Observer base class for watching changes to an {@link Adapter}.
* See {@link Adapter#registerAdapterDataObserver(AdapterDataObserver)}.
*/
public static abstract class AdapterDataObserver {
public void onChanged() {
// Do nothing
}
public void onItemRangeChanged(int positionStart, int itemCount) {
// do nothing
}
public void onItemRangeInserted(int positionStart, int itemCount) {
// do nothing
}
public void onItemRangeRemoved(int positionStart, int itemCount) {
// do nothing
}
public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
// do nothing
}
}
/**
* <p>Base class for smooth scrolling. Handles basic tracking of the target view position and
* provides methods to trigger a programmatic scroll.</p>
*
* @see LinearSmoothScroller
*/
public static abstract class SmoothScroller {
private int mTargetPosition = RecyclerView.NO_POSITION;
private RecyclerView mRecyclerView;
private LayoutManager mLayoutManager;
private boolean mPendingInitialRun;
private boolean mRunning;
private View mTargetView;
private final Action mRecyclingAction;
public SmoothScroller() {
mRecyclingAction = new Action(0, 0);
}
/**
* Starts a smooth scroll for the given target position.
* <p>In each animation step, {@link RecyclerView} will check
* for the target view and call either
* {@link #onTargetFound(android.view.View, RecyclerView.State, SmoothScroller.Action)} or
* {@link #onSeekTargetStep(int, int, RecyclerView.State, SmoothScroller.Action)} until
* SmoothScroller is stopped.</p>
*
* <p>Note that if RecyclerView finds the target view, it will automatically stop the
* SmoothScroller. This <b>does not</b> mean that scroll will stop, it only means it will
* stop calling SmoothScroller in each animation step.</p>
*/
void start(RecyclerView recyclerView, LayoutManager layoutManager) {
mRecyclerView = recyclerView;
mLayoutManager = layoutManager;
if (mTargetPosition == RecyclerView.NO_POSITION) {
throw new IllegalArgumentException("Invalid target position");
}
mRecyclerView.mState.mTargetPosition = mTargetPosition;
mRunning = true;
mPendingInitialRun = true;
mTargetView = findViewByPosition(getTargetPosition());
onStart();
mRecyclerView.mViewFlinger.postOnAnimation();
}
public void setTargetPosition(int targetPosition) {
mTargetPosition = targetPosition;
}
/**
* @return The LayoutManager to which this SmoothScroller is attached
*/
public LayoutManager getLayoutManager() {
return mLayoutManager;
}
/**
* Stops running the SmoothScroller in each animation callback. Note that this does not
* cancel any existing {@link Action} updated by
* {@link #onTargetFound(android.view.View, RecyclerView.State, SmoothScroller.Action)} or
* {@link #onSeekTargetStep(int, int, RecyclerView.State, SmoothScroller.Action)}.
*/
final protected void stop() {
if (!mRunning) {
return;
}
onStop();
mRecyclerView.mState.mTargetPosition = RecyclerView.NO_POSITION;
mTargetView = null;
mTargetPosition = RecyclerView.NO_POSITION;
mPendingInitialRun = false;
mRunning = false;
// trigger a cleanup
mLayoutManager.onSmoothScrollerStopped(this);
// clear references to avoid any potential leak by a custom smooth scroller
mLayoutManager = null;
mRecyclerView = null;
}
/**
* Returns true if SmoothScroller has been started but has not received the first
* animation
* callback yet.
*
* @return True if this SmoothScroller is waiting to start
*/
public boolean isPendingInitialRun() {
return mPendingInitialRun;
}
/**
* @return True if SmoothScroller is currently active
*/
public boolean isRunning() {
return mRunning;
}
/**
* Returns the adapter position of the target item
*
* @return Adapter position of the target item or
* {@link RecyclerView#NO_POSITION} if no target view is set.
*/
public int getTargetPosition() {
return mTargetPosition;
}
private void onAnimation(int dx, int dy) {
if (!mRunning || mTargetPosition == RecyclerView.NO_POSITION) {
stop();
}
mPendingInitialRun = false;
if (mTargetView != null) {
// verify target position
if (getChildPosition(mTargetView) == mTargetPosition) {
onTargetFound(mTargetView, mRecyclerView.mState, mRecyclingAction);
mRecyclingAction.runIfNecessary(mRecyclerView);
stop();
} else {
Log.e(TAG, "Passed over target position while smooth scrolling.");
mTargetView = null;
}
}
if (mRunning) {
onSeekTargetStep(dx, dy, mRecyclerView.mState, mRecyclingAction);
mRecyclingAction.runIfNecessary(mRecyclerView);
}
}
/**
* @see RecyclerView#getChildLayoutPosition(android.view.View)
*/
public int getChildPosition(View view) {
return mRecyclerView.getChildLayoutPosition(view);
}
/**
* @see RecyclerView.LayoutManager#getChildCount()
*/
public int getChildCount() {
return mRecyclerView.mLayout.getChildCount();
}
/**
* @see RecyclerView.LayoutManager#findViewByPosition(int)
*/
public View findViewByPosition(int position) {
return mRecyclerView.mLayout.findViewByPosition(position);
}
/**
* @see RecyclerView#scrollToPosition(int)
*/
public void instantScrollToPosition(int position) {
mRecyclerView.scrollToPosition(position);
}
protected void onChildAttachedToWindow(View child) {
if (getChildPosition(child) == getTargetPosition()) {
mTargetView = child;
if (DEBUG) {
Log.d(TAG, "smooth scroll target view has been attached");
}
}
}
/**
* Normalizes the vector.
* @param scrollVector The vector that points to the target scroll position
*/
protected void normalize(PointF scrollVector) {
final double magnitute = Math.sqrt(scrollVector.x * scrollVector.x + scrollVector.y *
scrollVector.y);
scrollVector.x /= magnitute;
scrollVector.y /= magnitute;
}
/**
* Called when smooth scroll is started. This might be a good time to do setup.
*/
abstract protected void onStart();
/**
* Called when smooth scroller is stopped. This is a good place to cleanup your state etc.
* @see #stop()
*/
abstract protected void onStop();
/**
* <p>RecyclerView will call this method each time it scrolls until it can find the target
* position in the layout.</p>
* <p>SmoothScroller should check dx, dy and if scroll should be changed, update the
* provided {@link Action} to define the next scroll.</p>
*
* @param dx Last scroll amount horizontally
* @param dy Last scroll amount verticaully
* @param state Transient state of RecyclerView
* @param action If you want to trigger a new smooth scroll and cancel the previous one,
* update this object.
*/
abstract protected void onSeekTargetStep(int dx, int dy, State state, Action action);
/**
* Called when the target position is laid out. This is the last callback SmoothScroller
* will receive and it should update the provided {@link Action} to define the scroll
* details towards the target view.
* @param targetView The view element which render the target position.
* @param state Transient state of RecyclerView
* @param action Action instance that you should update to define final scroll action
* towards the targetView
*/
abstract protected void onTargetFound(View targetView, State state, Action action);
/**
* Holds information about a smooth scroll request by a {@link SmoothScroller}.
*/
public static class Action {
public static final int UNDEFINED_DURATION = Integer.MIN_VALUE;
private int mDx;
private int mDy;
private int mDuration;
private Interpolator mInterpolator;
private boolean changed = false;
// we track this variable to inform custom implementer if they are updating the action
// in every animation callback
private int consecutiveUpdates = 0;
/**
* @param dx Pixels to scroll horizontally
* @param dy Pixels to scroll vertically
*/
public Action(int dx, int dy) {
this(dx, dy, UNDEFINED_DURATION, null);
}
/**
* @param dx Pixels to scroll horizontally
* @param dy Pixels to scroll vertically
* @param duration Duration of the animation in milliseconds
*/
public Action(int dx, int dy, int duration) {
this(dx, dy, duration, null);
}
/**
* @param dx Pixels to scroll horizontally
* @param dy Pixels to scroll vertically
* @param duration Duration of the animation in milliseconds
* @param interpolator Interpolator to be used when calculating scroll position in each
* animation step
*/
public Action(int dx, int dy, int duration, Interpolator interpolator) {
mDx = dx;
mDy = dy;
mDuration = duration;
mInterpolator = interpolator;
}
private void runIfNecessary(RecyclerView recyclerView) {
if (changed) {
validate();
if (mInterpolator == null) {
if (mDuration == UNDEFINED_DURATION) {
recyclerView.mViewFlinger.smoothScrollBy(mDx, mDy);
} else {
recyclerView.mViewFlinger.smoothScrollBy(mDx, mDy, mDuration);
}
} else {
recyclerView.mViewFlinger.smoothScrollBy(mDx, mDy, mDuration, mInterpolator);
}
consecutiveUpdates ++;
if (consecutiveUpdates > 10) {
// A new action is being set in every animation step. This looks like a bad
// implementation. Inform developer.
Log.e(TAG, "Smooth Scroll action is being updated too frequently. Make sure"
+ " you are not changing it unless necessary");
}
changed = false;
} else {
consecutiveUpdates = 0;
}
}
private void validate() {
if (mInterpolator != null && mDuration < 1) {
throw new IllegalStateException("If you provide an interpolator, you must"
+ " set a positive duration");
} else if (mDuration < 1) {
throw new IllegalStateException("Scroll duration must be a positive number");
}
}
public int getDx() {
return mDx;
}
public void setDx(int dx) {
changed = true;
mDx = dx;
}
public int getDy() {
return mDy;
}
public void setDy(int dy) {
changed = true;
mDy = dy;
}
public int getDuration() {
return mDuration;
}
public void setDuration(int duration) {
changed = true;
mDuration = duration;
}
public Interpolator getInterpolator() {
return mInterpolator;
}
/**
* Sets the interpolator to calculate scroll steps
* @param interpolator The interpolator to use. If you specify an interpolator, you must
* also set the duration.
* @see #setDuration(int)
*/
public void setInterpolator(Interpolator interpolator) {
changed = true;
mInterpolator = interpolator;
}
/**
* Updates the action with given parameters.
* @param dx Pixels to scroll horizontally
* @param dy Pixels to scroll vertically
* @param duration Duration of the animation in milliseconds
* @param interpolator Interpolator to be used when calculating scroll position in each
* animation step
*/
public void update(int dx, int dy, int duration, Interpolator interpolator) {
mDx = dx;
mDy = dy;
mDuration = duration;
mInterpolator = interpolator;
changed = true;
}
}
}
static class AdapterDataObservable extends Observable<AdapterDataObserver> {
public boolean hasObservers() {
return !mObservers.isEmpty();
}
public void notifyChanged() {
// since onChanged() is implemented by the app, it could do anything, including
// removing itself from {@link mObservers} - and that could cause problems if
// an iterator is used on the ArrayList {@link mObservers}.
// to avoid such problems, just march thru the list in the reverse order.
for (int i = mObservers.size() - 1; i >= 0; i--) {
mObservers.get(i).onChanged();
}
}
public void notifyItemRangeChanged(int positionStart, int itemCount) {
// since onItemRangeChanged() is implemented by the app, it could do anything, including
// removing itself from {@link mObservers} - and that could cause problems if
// an iterator is used on the ArrayList {@link mObservers}.
// to avoid such problems, just march thru the list in the reverse order.
for (int i = mObservers.size() - 1; i >= 0; i--) {
mObservers.get(i).onItemRangeChanged(positionStart, itemCount);
}
}
public void notifyItemRangeInserted(int positionStart, int itemCount) {
// since onItemRangeInserted() is implemented by the app, it could do anything,
// including removing itself from {@link mObservers} - and that could cause problems if
// an iterator is used on the ArrayList {@link mObservers}.
// to avoid such problems, just march thru the list in the reverse order.
for (int i = mObservers.size() - 1; i >= 0; i--) {
mObservers.get(i).onItemRangeInserted(positionStart, itemCount);
}
}
public void notifyItemRangeRemoved(int positionStart, int itemCount) {
// since onItemRangeRemoved() is implemented by the app, it could do anything, including
// removing itself from {@link mObservers} - and that could cause problems if
// an iterator is used on the ArrayList {@link mObservers}.
// to avoid such problems, just march thru the list in the reverse order.
for (int i = mObservers.size() - 1; i >= 0; i--) {
mObservers.get(i).onItemRangeRemoved(positionStart, itemCount);
}
}
public void notifyItemMoved(int fromPosition, int toPosition) {
for (int i = mObservers.size() - 1; i >= 0; i--) {
mObservers.get(i).onItemRangeMoved(fromPosition, toPosition, 1);
}
}
}
static class SavedState extends android.view.View.BaseSavedState {
Parcelable mLayoutState;
/**
* called by CREATOR
*/
SavedState(Parcel in) {
super(in);
mLayoutState = in.readParcelable(LayoutManager.class.getClassLoader());
}
/**
* Called by onSaveInstanceState
*/
SavedState(Parcelable superState) {
super(superState);
}
@Override
public void writeToParcel(Parcel dest, int flags) {
super.writeToParcel(dest, flags);
dest.writeParcelable(mLayoutState, 0);
}
private void copyFrom(SavedState other) {
mLayoutState = other.mLayoutState;
}
public static final Parcelable.Creator<SavedState> CREATOR
= new Parcelable.Creator<SavedState>() {
@Override
public SavedState createFromParcel(Parcel in) {
return new SavedState(in);
}
@Override
public SavedState[] newArray(int size) {
return new SavedState[size];
}
};
}
/**
* <p>Contains useful information about the current RecyclerView state like target scroll
* position or view focus. State object can also keep arbitrary data, identified by resource
* ids.</p>
* <p>Often times, RecyclerView components will need to pass information between each other.
* To provide a well defined data bus between components, RecyclerView passes the same State
* object to component callbacks and these components can use it to exchange data.</p>
* <p>If you implement custom components, you can use State's put/get/remove methods to pass
* data between your components without needing to manage their lifecycles.</p>
*/
public static class State {
private int mTargetPosition = RecyclerView.NO_POSITION;
ArrayMap<ViewHolder, ItemHolderInfo> mPreLayoutHolderMap =
new ArrayMap<ViewHolder, ItemHolderInfo>();
ArrayMap<ViewHolder, ItemHolderInfo> mPostLayoutHolderMap =
new ArrayMap<ViewHolder, ItemHolderInfo>();
// nullable
ArrayMap<Long, ViewHolder> mOldChangedHolders = new ArrayMap<Long, ViewHolder>();
private SparseArray<Object> mData;
/**
* Number of items adapter has.
*/
int mItemCount = 0;
/**
* Number of items adapter had in the previous layout.
*/
private int mPreviousLayoutItemCount = 0;
/**
* Number of items that were NOT laid out but has been deleted from the adapter after the
* previous layout.
*/
private int mDeletedInvisibleItemCountSincePreviousLayout = 0;
private boolean mStructureChanged = false;
private boolean mInPreLayout = false;
private boolean mRunSimpleAnimations = false;
private boolean mRunPredictiveAnimations = false;
State reset() {
mTargetPosition = RecyclerView.NO_POSITION;
if (mData != null) {
mData.clear();
}
mItemCount = 0;
mStructureChanged = false;
return this;
}
public boolean isPreLayout() {
return mInPreLayout;
}
/**
* Returns whether RecyclerView will run predictive animations in this layout pass
* or not.
*
* @return true if RecyclerView is calculating predictive animations to be run at the end
* of the layout pass.
*/
public boolean willRunPredictiveAnimations() {
return mRunPredictiveAnimations;
}
/**
* Returns whether RecyclerView will run simple animations in this layout pass
* or not.
*
* @return true if RecyclerView is calculating simple animations to be run at the end of
* the layout pass.
*/
public boolean willRunSimpleAnimations() {
return mRunSimpleAnimations;
}
/**
* Removes the mapping from the specified id, if there was any.
* @param resourceId Id of the resource you want to remove. It is suggested to use R.id.* to
* preserve cross functionality and avoid conflicts.
*/
public void remove(int resourceId) {
if (mData == null) {
return;
}
mData.remove(resourceId);
}
/**
* Gets the Object mapped from the specified id, or <code>null</code>
* if no such data exists.
*
* @param resourceId Id of the resource you want to remove. It is suggested to use R.id.*
* to
* preserve cross functionality and avoid conflicts.
*/
public <T> T get(int resourceId) {
if (mData == null) {
return null;
}
return (T) mData.get(resourceId);
}
/**
* Adds a mapping from the specified id to the specified value, replacing the previous
* mapping from the specified key if there was one.
*
* @param resourceId Id of the resource you want to add. It is suggested to use R.id.* to
* preserve cross functionality and avoid conflicts.
* @param data The data you want to associate with the resourceId.
*/
public void put(int resourceId, Object data) {
if (mData == null) {
mData = new SparseArray<Object>();
}
mData.put(resourceId, data);
}
/**
* If scroll is triggered to make a certain item visible, this value will return the
* adapter index of that item.
* @return Adapter index of the target item or
* {@link RecyclerView#NO_POSITION} if there is no target
* position.
*/
public int getTargetScrollPosition() {
return mTargetPosition;
}
/**
* Returns if current scroll has a target position.
* @return true if scroll is being triggered to make a certain position visible
* @see #getTargetScrollPosition()
*/
public boolean hasTargetScrollPosition() {
return mTargetPosition != RecyclerView.NO_POSITION;
}
/**
* @return true if the structure of the data set has changed since the last call to
* onLayoutChildren, false otherwise
*/
public boolean didStructureChange() {
return mStructureChanged;
}
/**
* Returns the total number of items that can be laid out. Note that this number is not
* necessarily equal to the number of items in the adapter, so you should always use this
* number for your position calculations and never access the adapter directly.
* <p>
* RecyclerView listens for Adapter's notify events and calculates the effects of adapter
* data changes on existing Views. These calculations are used to decide which animations
* should be run.
* <p>
* To support predictive animations, RecyclerView may rewrite or reorder Adapter changes to
* present the correct state to LayoutManager in pre-layout pass.
* <p>
* For example, a newly added item is not included in pre-layout item count because
* pre-layout reflects the contents of the adapter before the item is added. Behind the
* scenes, RecyclerView offsets {@link Recycler#getViewForPosition(int)} calls such that
* LayoutManager does not know about the new item's existence in pre-layout. The item will
* be available in second layout pass and will be included in the item count. Similar
* adjustments are made for moved and removed items as well.
* <p>
* You can get the adapter's item count via {@link LayoutManager#getItemCount()} method.
*
* @return The number of items currently available
* @see LayoutManager#getItemCount()
*/
public int getItemCount() {
return mInPreLayout ?
(mPreviousLayoutItemCount - mDeletedInvisibleItemCountSincePreviousLayout) :
mItemCount;
}
public void onViewRecycled(ViewHolder holder) {
mPreLayoutHolderMap.remove(holder);
mPostLayoutHolderMap.remove(holder);
if (mOldChangedHolders != null) {
removeFrom(mOldChangedHolders, holder);
}
// holder cannot be in new list.
}
public void onViewIgnored(ViewHolder holder) {
onViewRecycled(holder);
}
private void removeFrom(ArrayMap<Long, ViewHolder> holderMap, ViewHolder holder) {
for (int i = holderMap.size() - 1; i >= 0; i --) {
if (holder == holderMap.valueAt(i)) {
holderMap.removeAt(i);
return;
}
}
}
@Override
public String toString() {
return "State{" +
"mTargetPosition=" + mTargetPosition +
", mPreLayoutHolderMap=" + mPreLayoutHolderMap +
", mPostLayoutHolderMap=" + mPostLayoutHolderMap +
", mData=" + mData +
", mItemCount=" + mItemCount +
", mPreviousLayoutItemCount=" + mPreviousLayoutItemCount +
", mDeletedInvisibleItemCountSincePreviousLayout="
+ mDeletedInvisibleItemCountSincePreviousLayout +
", mStructureChanged=" + mStructureChanged +
", mInPreLayout=" + mInPreLayout +
", mRunSimpleAnimations=" + mRunSimpleAnimations +
", mRunPredictiveAnimations=" + mRunPredictiveAnimations +
'}';
}
}
/**
* Internal listener that manages items after animations finish. This is how items are
* retained (not recycled) during animations, but allowed to be recycled afterwards.
* It depends on the contract with the ItemAnimator to call the appropriate dispatch*Finished()
* method on the animator's listener when it is done animating any item.
*/
private class ItemAnimatorRestoreListener implements ItemAnimator.ItemAnimatorListener {
@Override
public void onRemoveFinished(ViewHolder item) {
item.setIsRecyclable(true);
if (!removeAnimatingView(item.itemView) && item.isTmpDetached()) {
removeDetachedView(item.itemView, false);
}
}
@Override
public void onAddFinished(ViewHolder item) {
item.setIsRecyclable(true);
if (!item.shouldBeKeptAsChild()) {
removeAnimatingView(item.itemView);
}
}
@Override
public void onMoveFinished(ViewHolder item) {
item.setIsRecyclable(true);
if (!item.shouldBeKeptAsChild()) {
removeAnimatingView(item.itemView);
}
}
@Override
public void onChangeFinished(ViewHolder item) {
item.setIsRecyclable(true);
/**
* We check both shadowed and shadowing because a ViewHolder may get both roles at the
* same time.
*
* Assume this flow:
* item X is represented by VH_1. Then itemX changes, so we create VH_2 .
* RV sets the following and calls item animator:
* VH_1.shadowed = VH_2;
* VH_1.mChanged = true;
* VH_2.shadowing =VH_1;
*
* Then, before the first change finishes, item changes again so we create VH_3.
* RV sets the following and calls item animator:
* VH_2.shadowed = VH_3
* VH_2.mChanged = true
* VH_3.shadowing = VH_2
*
* Because VH_2 already has an animation, it will be cancelled. At this point VH_2 has
* both shadowing and shadowed fields set. Shadowing information is obsolete now
* because the first animation where VH_2 is newViewHolder is not valid anymore.
* We ended up in this case because VH_2 played both roles. On the other hand,
* we DO NOT want to clear its changed flag.
*
* If second change was simply reverting first change, we would find VH_1 in
* {@link Recycler#getScrapViewForPosition(int, int, boolean)} and recycle it before
* re-using
*/
if (item.mShadowedHolder != null && item.mShadowingHolder == null) { // old vh
item.mShadowedHolder = null;
item.setFlags(~ViewHolder.FLAG_CHANGED, item.mFlags);
}
// always null this because an OldViewHolder can never become NewViewHolder w/o being
// recycled.
item.mShadowingHolder = null;
if (!item.shouldBeKeptAsChild()) {
removeAnimatingView(item.itemView);
}
}
};
/**
* This class defines the animations that take place on items as changes are made
* to the adapter.
*
* Subclasses of ItemAnimator can be used to implement custom animations for actions on
* ViewHolder items. The RecyclerView will manage retaining these items while they
* are being animated, but implementors must call the appropriate "Starting"
* ({@link #dispatchRemoveStarting(ViewHolder)}, {@link #dispatchMoveStarting(ViewHolder)},
* {@link #dispatchChangeStarting(ViewHolder, boolean)}, or
* {@link #dispatchAddStarting(ViewHolder)})
* and "Finished" ({@link #dispatchRemoveFinished(ViewHolder)},
* {@link #dispatchMoveFinished(ViewHolder)},
* {@link #dispatchChangeFinished(ViewHolder, boolean)},
* or {@link #dispatchAddFinished(ViewHolder)}) methods when each item animation is
* being started and ended.
*
* <p>By default, RecyclerView uses {@link DefaultItemAnimator}</p>
*
* @see #setItemAnimator(ItemAnimator)
*/
public static abstract class ItemAnimator {
private ItemAnimatorListener mListener = null;
private ArrayList<ItemAnimatorFinishedListener> mFinishedListeners =
new ArrayList<ItemAnimatorFinishedListener>();
private long mAddDuration = 120;
private long mRemoveDuration = 120;
private long mMoveDuration = 250;
private long mChangeDuration = 250;
private boolean mSupportsChangeAnimations = true;
/**
* Gets the current duration for which all move animations will run.
*
* @return The current move duration
*/
public long getMoveDuration() {
return mMoveDuration;
}
/**
* Sets the duration for which all move animations will run.
*
* @param moveDuration The move duration
*/
public void setMoveDuration(long moveDuration) {
mMoveDuration = moveDuration;
}
/**
* Gets the current duration for which all add animations will run.
*
* @return The current add duration
*/
public long getAddDuration() {
return mAddDuration;
}
/**
* Sets the duration for which all add animations will run.
*
* @param addDuration The add duration
*/
public void setAddDuration(long addDuration) {
mAddDuration = addDuration;
}
/**
* Gets the current duration for which all remove animations will run.
*
* @return The current remove duration
*/
public long getRemoveDuration() {
return mRemoveDuration;
}
/**
* Sets the duration for which all remove animations will run.
*
* @param removeDuration The remove duration
*/
public void setRemoveDuration(long removeDuration) {
mRemoveDuration = removeDuration;
}
/**
* Gets the current duration for which all change animations will run.
*
* @return The current change duration
*/
public long getChangeDuration() {
return mChangeDuration;
}
/**
* Sets the duration for which all change animations will run.
*
* @param changeDuration The change duration
*/
public void setChangeDuration(long changeDuration) {
mChangeDuration = changeDuration;
}
/**
* Returns whether this ItemAnimator supports animations of change events.
*
* @return true if change animations are supported, false otherwise
*/
public boolean getSupportsChangeAnimations() {
return mSupportsChangeAnimations;
}
/**
* Sets whether this ItemAnimator supports animations of item change events.
* If you set this property to false, actions on the data set which change the
* contents of items will not be animated. What those animations are is left
* up to the discretion of the ItemAnimator subclass, in its
* {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)} implementation.
* The value of this property is true by default.
*
* @see Adapter#notifyItemChanged(int)
* @see Adapter#notifyItemRangeChanged(int, int)
*
* @param supportsChangeAnimations true if change animations are supported by
* this ItemAnimator, false otherwise. If the property is false, the ItemAnimator
* will not receive a call to
* {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)} when changes occur.
*/
public void setSupportsChangeAnimations(boolean supportsChangeAnimations) {
mSupportsChangeAnimations = supportsChangeAnimations;
}
/**
* Internal only:
* Sets the listener that must be called when the animator is finished
* animating the item (or immediately if no animation happens). This is set
* internally and is not intended to be set by external code.
*
* @param listener The listener that must be called.
*/
void setListener(ItemAnimatorListener listener) {
mListener = listener;
}
/**
* Called when there are pending animations waiting to be started. This state
* is governed by the return values from {@link #animateAdd(ViewHolder) animateAdd()},
* {@link #animateMove(ViewHolder, int, int, int, int) animateMove()}, and
* {@link #animateRemove(ViewHolder) animateRemove()}, which inform the
* RecyclerView that the ItemAnimator wants to be called later to start the
* associated animations. runPendingAnimations() will be scheduled to be run
* on the next frame.
*/
abstract public void runPendingAnimations();
/**
* Called when an item is removed from the RecyclerView. Implementors can choose
* whether and how to animate that change, but must always call
* {@link #dispatchRemoveFinished(ViewHolder)} when done, either
* immediately (if no animation will occur) or after the animation actually finishes.
* The return value indicates whether an animation has been set up and whether the
* ItemAnimator's {@link #runPendingAnimations()} method should be called at the
* next opportunity. This mechanism allows ItemAnimator to set up individual animations
* as separate calls to {@link #animateAdd(ViewHolder) animateAdd()},
* {@link #animateMove(ViewHolder, int, int, int, int) animateMove()},
* {@link #animateRemove(ViewHolder) animateRemove()}, and
* {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)} come in one by one,
* then start the animations together in the later call to {@link #runPendingAnimations()}.
*
* <p>This method may also be called for disappearing items which continue to exist in the
* RecyclerView, but for which the system does not have enough information to animate
* them out of view. In that case, the default animation for removing items is run
* on those items as well.</p>
*
* @param holder The item that is being removed.
* @return true if a later call to {@link #runPendingAnimations()} is requested,
* false otherwise.
*/
abstract public boolean animateRemove(ViewHolder holder);
/**
* Called when an item is added to the RecyclerView. Implementors can choose
* whether and how to animate that change, but must always call
* {@link #dispatchAddFinished(ViewHolder)} when done, either
* immediately (if no animation will occur) or after the animation actually finishes.
* The return value indicates whether an animation has been set up and whether the
* ItemAnimator's {@link #runPendingAnimations()} method should be called at the
* next opportunity. This mechanism allows ItemAnimator to set up individual animations
* as separate calls to {@link #animateAdd(ViewHolder) animateAdd()},
* {@link #animateMove(ViewHolder, int, int, int, int) animateMove()},
* {@link #animateRemove(ViewHolder) animateRemove()}, and
* {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)} come in one by one,
* then start the animations together in the later call to {@link #runPendingAnimations()}.
*
* <p>This method may also be called for appearing items which were already in the
* RecyclerView, but for which the system does not have enough information to animate
* them into view. In that case, the default animation for adding items is run
* on those items as well.</p>
*
* @param holder The item that is being added.
* @return true if a later call to {@link #runPendingAnimations()} is requested,
* false otherwise.
*/
abstract public boolean animateAdd(ViewHolder holder);
/**
* Called when an item is moved in the RecyclerView. Implementors can choose
* whether and how to animate that change, but must always call
* {@link #dispatchMoveFinished(ViewHolder)} when done, either
* immediately (if no animation will occur) or after the animation actually finishes.
* The return value indicates whether an animation has been set up and whether the
* ItemAnimator's {@link #runPendingAnimations()} method should be called at the
* next opportunity. This mechanism allows ItemAnimator to set up individual animations
* as separate calls to {@link #animateAdd(ViewHolder) animateAdd()},
* {@link #animateMove(ViewHolder, int, int, int, int) animateMove()},
* {@link #animateRemove(ViewHolder) animateRemove()}, and
* {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)} come in one by one,
* then start the animations together in the later call to {@link #runPendingAnimations()}.
*
* @param holder The item that is being moved.
* @return true if a later call to {@link #runPendingAnimations()} is requested,
* false otherwise.
*/
abstract public boolean animateMove(ViewHolder holder, int fromX, int fromY,
int toX, int toY);
/**
* Called when an item is changed in the RecyclerView, as indicated by a call to
* {@link Adapter#notifyItemChanged(int)} or
* {@link Adapter#notifyItemRangeChanged(int, int)}.
* <p>
* Implementers can choose whether and how to animate changes, but must always call
* {@link #dispatchChangeFinished(ViewHolder, boolean)} for each non-null ViewHolder,
* either immediately (if no animation will occur) or after the animation actually finishes.
* The return value indicates whether an animation has been set up and whether the
* ItemAnimator's {@link #runPendingAnimations()} method should be called at the
* next opportunity. This mechanism allows ItemAnimator to set up individual animations
* as separate calls to {@link #animateAdd(ViewHolder) animateAdd()},
* {@link #animateMove(ViewHolder, int, int, int, int) animateMove()},
* {@link #animateRemove(ViewHolder) animateRemove()}, and
* {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)} come in one by one,
* then start the animations together in the later call to {@link #runPendingAnimations()}.
*
* @param oldHolder The original item that changed.
* @param newHolder The new item that was created with the changed content. Might be null
* @param fromLeft Left of the old view holder
* @param fromTop Top of the old view holder
* @param toLeft Left of the new view holder
* @param toTop Top of the new view holder
* @return true if a later call to {@link #runPendingAnimations()} is requested,
* false otherwise.
*/
abstract public boolean animateChange(ViewHolder oldHolder,
ViewHolder newHolder, int fromLeft, int fromTop, int toLeft, int toTop);
/**
* Method to be called by subclasses when a remove animation is done.
*
* @param item The item which has been removed
*/
public final void dispatchRemoveFinished(ViewHolder item) {
onRemoveFinished(item);
if (mListener != null) {
mListener.onRemoveFinished(item);
}
}
/**
* Method to be called by subclasses when a move animation is done.
*
* @param item The item which has been moved
*/
public final void dispatchMoveFinished(ViewHolder item) {
onMoveFinished(item);
if (mListener != null) {
mListener.onMoveFinished(item);
}
}
/**
* Method to be called by subclasses when an add animation is done.
*
* @param item The item which has been added
*/
public final void dispatchAddFinished(ViewHolder item) {
onAddFinished(item);
if (mListener != null) {
mListener.onAddFinished(item);
}
}
/**
* Method to be called by subclasses when a change animation is done.
*
* @see #animateChange(ViewHolder, ViewHolder, int, int, int, int)
* @param item The item which has been changed (this method must be called for
* each non-null ViewHolder passed into
* {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)}).
* @param oldItem true if this is the old item that was changed, false if
* it is the new item that replaced the old item.
*/
public final void dispatchChangeFinished(ViewHolder item, boolean oldItem) {
onChangeFinished(item, oldItem);
if (mListener != null) {
mListener.onChangeFinished(item);
}
}
/**
* Method to be called by subclasses when a remove animation is being started.
*
* @param item The item being removed
*/
public final void dispatchRemoveStarting(ViewHolder item) {
onRemoveStarting(item);
}
/**
* Method to be called by subclasses when a move animation is being started.
*
* @param item The item being moved
*/
public final void dispatchMoveStarting(ViewHolder item) {
onMoveStarting(item);
}
/**
* Method to be called by subclasses when an add animation is being started.
*
* @param item The item being added
*/
public final void dispatchAddStarting(ViewHolder item) {
onAddStarting(item);
}
/**
* Method to be called by subclasses when a change animation is being started.
*
* @param item The item which has been changed (this method must be called for
* each non-null ViewHolder passed into
* {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)}).
* @param oldItem true if this is the old item that was changed, false if
* it is the new item that replaced the old item.
*/
public final void dispatchChangeStarting(ViewHolder item, boolean oldItem) {
onChangeStarting(item, oldItem);
}
/**
* Method called when an animation on a view should be ended immediately.
* This could happen when other events, like scrolling, occur, so that
* animating views can be quickly put into their proper end locations.
* Implementations should ensure that any animations running on the item
* are canceled and affected properties are set to their end values.
* Also, appropriate dispatch methods (e.g., {@link #dispatchAddFinished(ViewHolder)}
* should be called since the animations are effectively done when this
* method is called.
*
* @param item The item for which an animation should be stopped.
*/
abstract public void endAnimation(ViewHolder item);
/**
* Method called when all item animations should be ended immediately.
* This could happen when other events, like scrolling, occur, so that
* animating views can be quickly put into their proper end locations.
* Implementations should ensure that any animations running on any items
* are canceled and affected properties are set to their end values.
* Also, appropriate dispatch methods (e.g., {@link #dispatchAddFinished(ViewHolder)}
* should be called since the animations are effectively done when this
* method is called.
*/
abstract public void endAnimations();
/**
* Method which returns whether there are any item animations currently running.
* This method can be used to determine whether to delay other actions until
* animations end.
*
* @return true if there are any item animations currently running, false otherwise.
*/
abstract public boolean isRunning();
/**
* Like {@link #isRunning()}, this method returns whether there are any item
* animations currently running. Addtionally, the listener passed in will be called
* when there are no item animations running, either immediately (before the method
* returns) if no animations are currently running, or when the currently running
* animations are {@link #dispatchAnimationsFinished() finished}.
*
* <p>Note that the listener is transient - it is either called immediately and not
* stored at all, or stored only until it is called when running animations
* are finished sometime later.</p>
*
* @param listener A listener to be called immediately if no animations are running
* or later when currently-running animations have finished. A null listener is
* equivalent to calling {@link #isRunning()}.
* @return true if there are any item animations currently running, false otherwise.
*/
public final boolean isRunning(ItemAnimatorFinishedListener listener) {
boolean running = isRunning();
if (listener != null) {
if (!running) {
listener.onAnimationsFinished();
} else {
mFinishedListeners.add(listener);
}
}
return running;
}
/**
* The interface to be implemented by listeners to animation events from this
* ItemAnimator. This is used internally and is not intended for developers to
* create directly.
*/
interface ItemAnimatorListener {
void onRemoveFinished(ViewHolder item);
void onAddFinished(ViewHolder item);
void onMoveFinished(ViewHolder item);
void onChangeFinished(ViewHolder item);
}
/**
* This method should be called by ItemAnimator implementations to notify
* any listeners that all pending and active item animations are finished.
*/
public final void dispatchAnimationsFinished() {
final int count = mFinishedListeners.size();
for (int i = 0; i < count; ++i) {
mFinishedListeners.get(i).onAnimationsFinished();
}
mFinishedListeners.clear();
}
/**
* This interface is used to inform listeners when all pending or running animations
* in an ItemAnimator are finished. This can be used, for example, to delay an action
* in a data set until currently-running animations are complete.
*
* @see #isRunning(ItemAnimatorFinishedListener)
*/
public interface ItemAnimatorFinishedListener {
void onAnimationsFinished();
}
/**
* Called when a remove animation is being started on the given ViewHolder.
* The default implementation does nothing. Subclasses may wish to override
* this method to handle any ViewHolder-specific operations linked to animation
* lifecycles.
*
* @param item The ViewHolder being animated.
*/
public void onRemoveStarting(ViewHolder item) {}
/**
* Called when a remove animation has ended on the given ViewHolder.
* The default implementation does nothing. Subclasses may wish to override
* this method to handle any ViewHolder-specific operations linked to animation
* lifecycles.
*
* @param item The ViewHolder being animated.
*/
public void onRemoveFinished(ViewHolder item) {}
/**
* Called when an add animation is being started on the given ViewHolder.
* The default implementation does nothing. Subclasses may wish to override
* this method to handle any ViewHolder-specific operations linked to animation
* lifecycles.
*
* @param item The ViewHolder being animated.
*/
public void onAddStarting(ViewHolder item) {}
/**
* Called when an add animation has ended on the given ViewHolder.
* The default implementation does nothing. Subclasses may wish to override
* this method to handle any ViewHolder-specific operations linked to animation
* lifecycles.
*
* @param item The ViewHolder being animated.
*/
public void onAddFinished(ViewHolder item) {}
/**
* Called when a move animation is being started on the given ViewHolder.
* The default implementation does nothing. Subclasses may wish to override
* this method to handle any ViewHolder-specific operations linked to animation
* lifecycles.
*
* @param item The ViewHolder being animated.
*/
public void onMoveStarting(ViewHolder item) {}
/**
* Called when a move animation has ended on the given ViewHolder.
* The default implementation does nothing. Subclasses may wish to override
* this method to handle any ViewHolder-specific operations linked to animation
* lifecycles.
*
* @param item The ViewHolder being animated.
*/
public void onMoveFinished(ViewHolder item) {}
/**
* Called when a change animation is being started on the given ViewHolder.
* The default implementation does nothing. Subclasses may wish to override
* this method to handle any ViewHolder-specific operations linked to animation
* lifecycles.
*
* @param item The ViewHolder being animated.
* @param oldItem true if this is the old item that was changed, false if
* it is the new item that replaced the old item.
*/
public void onChangeStarting(ViewHolder item, boolean oldItem) {}
/**
* Called when a change animation has ended on the given ViewHolder.
* The default implementation does nothing. Subclasses may wish to override
* this method to handle any ViewHolder-specific operations linked to animation
* lifecycles.
*
* @param item The ViewHolder being animated.
* @param oldItem true if this is the old item that was changed, false if
* it is the new item that replaced the old item.
*/
public void onChangeFinished(ViewHolder item, boolean oldItem) {}
}
/**
* Internal data structure that holds information about an item's bounds.
* This information is used in calculating item animations.
*/
private static class ItemHolderInfo {
ViewHolder holder;
int left, top, right, bottom;
ItemHolderInfo(ViewHolder holder, int left, int top, int right, int bottom) {
this.holder = holder;
this.left = left;
this.top = top;
this.right = right;
this.bottom = bottom;
}
}
}
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