/*
* Copyright (C) 2006 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.widget;
import android.os.Build;
import android.os.Parcel;
import android.os.Parcelable;
import com.android.internal.R;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.os.Bundle;
import android.os.StrictMode;
import android.util.AttributeSet;
import android.util.Log;
import android.view.FocusFinder;
import android.view.InputDevice;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewDebug;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;
import android.view.animation.AnimationUtils;
import java.util.List;
/**
* Layout container for a view hierarchy that can be scrolled by the user,
* allowing it to be larger than the physical display. A ScrollView
* is a {@link FrameLayout}, meaning you should place one child in it
* containing the entire contents to scroll; this child may itself be a layout
* manager with a complex hierarchy of objects. A child that is often used
* is a {@link LinearLayout} in a vertical orientation, presenting a vertical
* array of top-level items that the user can scroll through.
* <p>You should never use a ScrollView with a {@link ListView}, because
* ListView takes care of its own vertical scrolling. Most importantly, doing this
* defeats all of the important optimizations in ListView for dealing with
* large lists, since it effectively forces the ListView to display its entire
* list of items to fill up the infinite container supplied by ScrollView.
* <p>The {@link TextView} class also
* takes care of its own scrolling, so does not require a ScrollView, but
* using the two together is possible to achieve the effect of a text view
* within a larger container.
*
* <p>ScrollView only supports vertical scrolling. For horizontal scrolling,
* use {@link HorizontalScrollView}.
*
* @attr ref android.R.styleable#ScrollView_fillViewport
*/
public class ScrollView extends FrameLayout {
static final int ANIMATED_SCROLL_GAP = 250;
static final float MAX_SCROLL_FACTOR = 0.5f;
private static final String TAG = "ScrollView";
private long mLastScroll;
private final Rect mTempRect = new Rect();
private OverScroller mScroller;
private EdgeEffect mEdgeGlowTop;
private EdgeEffect mEdgeGlowBottom;
/**
* Position of the last motion event.
*/
private int mLastMotionY;
/**
* True when the layout has changed but the traversal has not come through yet.
* Ideally the view hierarchy would keep track of this for us.
*/
private boolean mIsLayoutDirty = true;
/**
* The child to give focus to in the event that a child has requested focus while the
* layout is dirty. This prevents the scroll from being wrong if the child has not been
* laid out before requesting focus.
*/
private View mChildToScrollTo = null;
/**
* True if the user is currently dragging this ScrollView around. This is
* not the same as 'is being flinged', which can be checked by
* mScroller.isFinished() (flinging begins when the user lifts his finger).
*/
private boolean mIsBeingDragged = false;
/**
* Determines speed during touch scrolling
*/
private VelocityTracker mVelocityTracker;
/**
* When set to true, the scroll view measure its child to make it fill the currently
* visible area.
*/
@ViewDebug.ExportedProperty(category = "layout")
private boolean mFillViewport;
/**
* Whether arrow scrolling is animated.
*/
private boolean mSmoothScrollingEnabled = true;
private int mTouchSlop;
private int mMinimumVelocity;
private int mMaximumVelocity;
private int mOverscrollDistance;
private int mOverflingDistance;
/**
* ID of the active pointer. This is used to retain consistency during
* drags/flings if multiple pointers are used.
*/
private int mActivePointerId = INVALID_POINTER;
/**
* Used during scrolling to retrieve the new offset within the window.
*/
private final int[] mScrollOffset = new int[2];
private final int[] mScrollConsumed = new int[2];
private int mNestedYOffset;
/**
* The StrictMode "critical time span" objects to catch animation
* stutters. Non-null when a time-sensitive animation is
* in-flight. Must call finish() on them when done animating.
* These are no-ops on user builds.
*/
private StrictMode.Span mScrollStrictSpan = null; // aka "drag"
private StrictMode.Span mFlingStrictSpan = null;
/**
* Sentinel value for no current active pointer.
* Used by {@link #mActivePointerId}.
*/
private static final int INVALID_POINTER = -1;
private SavedState mSavedState;
public ScrollView(Context context) {
this(context, null);
}
public ScrollView(Context context, AttributeSet attrs) {
this(context, attrs, com.android.internal.R.attr.scrollViewStyle);
}
public ScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
this(context, attrs, defStyleAttr, 0);
}
public ScrollView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
initScrollView();
final TypedArray a = context.obtainStyledAttributes(
attrs, com.android.internal.R.styleable.ScrollView, defStyleAttr, defStyleRes);
setFillViewport(a.getBoolean(R.styleable.ScrollView_fillViewport, false));
a.recycle();
}
@Override
public boolean shouldDelayChildPressedState() {
return true;
}
@Override
protected float getTopFadingEdgeStrength() {
if (getChildCount() == 0) {
return 0.0f;
}
final int length = getVerticalFadingEdgeLength();
if (mScrollY < length) {
return mScrollY / (float) length;
}
return 1.0f;
}
@Override
protected float getBottomFadingEdgeStrength() {
if (getChildCount() == 0) {
return 0.0f;
}
final int length = getVerticalFadingEdgeLength();
final int bottomEdge = getHeight() - mPaddingBottom;
final int span = getChildAt(0).getBottom() - mScrollY - bottomEdge;
if (span < length) {
return span / (float) length;
}
return 1.0f;
}
/**
* @return The maximum amount this scroll view will scroll in response to
* an arrow event.
*/
public int getMaxScrollAmount() {
return (int) (MAX_SCROLL_FACTOR * (mBottom - mTop));
}
private void initScrollView() {
mScroller = new OverScroller(getContext());
setFocusable(true);
setDescendantFocusability(FOCUS_AFTER_DESCENDANTS);
setWillNotDraw(false);
final ViewConfiguration configuration = ViewConfiguration.get(mContext);
mTouchSlop = configuration.getScaledTouchSlop();
mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
mOverscrollDistance = configuration.getScaledOverscrollDistance();
mOverflingDistance = configuration.getScaledOverflingDistance();
}
@Override
public void addView(View child) {
if (getChildCount() > 0) {
throw new IllegalStateException("ScrollView can host only one direct child");
}
super.addView(child);
}
@Override
public void addView(View child, int index) {
if (getChildCount() > 0) {
throw new IllegalStateException("ScrollView can host only one direct child");
}
super.addView(child, index);
}
@Override
public void addView(View child, ViewGroup.LayoutParams params) {
if (getChildCount() > 0) {
throw new IllegalStateException("ScrollView can host only one direct child");
}
super.addView(child, params);
}
@Override
public void addView(View child, int index, ViewGroup.LayoutParams params) {
if (getChildCount() > 0) {
throw new IllegalStateException("ScrollView can host only one direct child");
}
super.addView(child, index, params);
}
/**
* @return Returns true this ScrollView can be scrolled
*/
private boolean canScroll() {
View child = getChildAt(0);
if (child != null) {
int childHeight = child.getHeight();
return getHeight() < childHeight + mPaddingTop + mPaddingBottom;
}
return false;
}
/**
* Indicates whether this ScrollView's content is stretched to fill the viewport.
*
* @return True if the content fills the viewport, false otherwise.
*
* @attr ref android.R.styleable#ScrollView_fillViewport
*/
public boolean isFillViewport() {
return mFillViewport;
}
/**
* Indicates this ScrollView whether it should stretch its content height to fill
* the viewport or not.
*
* @param fillViewport True to stretch the content's height to the viewport's
* boundaries, false otherwise.
*
* @attr ref android.R.styleable#ScrollView_fillViewport
*/
public void setFillViewport(boolean fillViewport) {
if (fillViewport != mFillViewport) {
mFillViewport = fillViewport;
requestLayout();
}
}
/**
* @return Whether arrow scrolling will animate its transition.
*/
public boolean isSmoothScrollingEnabled() {
return mSmoothScrollingEnabled;
}
/**
* Set whether arrow scrolling will animate its transition.
* @param smoothScrollingEnabled whether arrow scrolling will animate its transition
*/
public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) {
mSmoothScrollingEnabled = smoothScrollingEnabled;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (!mFillViewport) {
return;
}
final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if (heightMode == MeasureSpec.UNSPECIFIED) {
return;
}
if (getChildCount() > 0) {
final View child = getChildAt(0);
int height = getMeasuredHeight();
if (child.getMeasuredHeight() < height) {
final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams();
int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec,
mPaddingLeft + mPaddingRight, lp.width);
height -= mPaddingTop;
height -= mPaddingBottom;
int childHeightMeasureSpec =
MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
}
}
@Override
public boolean dispatchKeyEvent(KeyEvent event) {
// Let the focused view and/or our descendants get the key first
return super.dispatchKeyEvent(event) || executeKeyEvent(event);
}
/**
* You can call this function yourself to have the scroll view perform
* scrolling from a key event, just as if the event had been dispatched to
* it by the view hierarchy.
*
* @param event The key event to execute.
* @return Return true if the event was handled, else false.
*/
public boolean executeKeyEvent(KeyEvent event) {
mTempRect.setEmpty();
if (!canScroll()) {
if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) {
View currentFocused = findFocus();
if (currentFocused == this) currentFocused = null;
View nextFocused = FocusFinder.getInstance().findNextFocus(this,
currentFocused, View.FOCUS_DOWN);
return nextFocused != null
&& nextFocused != this
&& nextFocused.requestFocus(View.FOCUS_DOWN);
}
return false;
}
boolean handled = false;
if (event.getAction() == KeyEvent.ACTION_DOWN) {
switch (event.getKeyCode()) {
case KeyEvent.KEYCODE_DPAD_UP:
if (!event.isAltPressed()) {
handled = arrowScroll(View.FOCUS_UP);
} else {
handled = fullScroll(View.FOCUS_UP);
}
break;
case KeyEvent.KEYCODE_DPAD_DOWN:
if (!event.isAltPressed()) {
handled = arrowScroll(View.FOCUS_DOWN);
} else {
handled = fullScroll(View.FOCUS_DOWN);
}
break;
case KeyEvent.KEYCODE_SPACE:
pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN);
break;
}
}
return handled;
}
private boolean inChild(int x, int y) {
if (getChildCount() > 0) {
final int scrollY = mScrollY;
final View child = getChildAt(0);
return !(y < child.getTop() - scrollY
|| y >= child.getBottom() - scrollY
|| x < child.getLeft()
|| x >= child.getRight());
}
return false;
}
private void initOrResetVelocityTracker() {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
} else {
mVelocityTracker.clear();
}
}
private void initVelocityTrackerIfNotExists() {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
}
private void recycleVelocityTracker() {
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
}
@Override
public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
if (disallowIntercept) {
recycleVelocityTracker();
}
super.requestDisallowInterceptTouchEvent(disallowIntercept);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
/*
* This method JUST determines whether we want to intercept the motion.
* If we return true, onMotionEvent will be called and we do the actual
* scrolling there.
*/
/*
* Shortcut the most recurring case: the user is in the dragging
* state and he is moving his finger. We want to intercept this
* motion.
*/
final int action = ev.getAction();
if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) {
return true;
}
/*
* Don't try to intercept touch if we can't scroll anyway.
*/
if (getScrollY() == 0 && !canScrollVertically(1)) {
return false;
}
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_MOVE: {
/*
* mIsBeingDragged == false, otherwise the shortcut would have caught it. Check
* whether the user has moved far enough from his original down touch.
*/
/*
* Locally do absolute value. mLastMotionY is set to the y value
* of the down event.
*/
final int activePointerId = mActivePointerId;
if (activePointerId == INVALID_POINTER) {
// If we don't have a valid id, the touch down wasn't on content.
break;
}
final int pointerIndex = ev.findPointerIndex(activePointerId);
if (pointerIndex == -1) {
Log.e(TAG, "Invalid pointerId=" + activePointerId
+ " in onInterceptTouchEvent");
break;
}
final int y = (int) ev.getY(pointerIndex);
final int yDiff = Math.abs(y - mLastMotionY);
if (yDiff > mTouchSlop && (getNestedScrollAxes() & SCROLL_AXIS_VERTICAL) == 0) {
mIsBeingDragged = true;
mLastMotionY = y;
initVelocityTrackerIfNotExists();
mVelocityTracker.addMovement(ev);
mNestedYOffset = 0;
if (mScrollStrictSpan == null) {
mScrollStrictSpan = StrictMode.enterCriticalSpan("ScrollView-scroll");
}
final ViewParent parent = getParent();
if (parent != null) {
parent.requestDisallowInterceptTouchEvent(true);
}
}
break;
}
case MotionEvent.ACTION_DOWN: {
final int y = (int) ev.getY();
if (!inChild((int) ev.getX(), (int) y)) {
mIsBeingDragged = false;
recycleVelocityTracker();
break;
}
/*
* Remember location of down touch.
* ACTION_DOWN always refers to pointer index 0.
*/
mLastMotionY = y;
mActivePointerId = ev.getPointerId(0);
initOrResetVelocityTracker();
mVelocityTracker.addMovement(ev);
/*
* If being flinged and user touches the screen, initiate drag;
* otherwise don't. mScroller.isFinished should be false when
* being flinged.
*/
mIsBeingDragged = !mScroller.isFinished();
if (mIsBeingDragged && mScrollStrictSpan == null) {
mScrollStrictSpan = StrictMode.enterCriticalSpan("ScrollView-scroll");
}
startNestedScroll(SCROLL_AXIS_VERTICAL);
break;
}
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
/* Release the drag */
mIsBeingDragged = false;
mActivePointerId = INVALID_POINTER;
recycleVelocityTracker();
if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) {
postInvalidateOnAnimation();
}
stopNestedScroll();
break;
case MotionEvent.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
break;
}
/*
* The only time we want to intercept motion events is if we are in the
* drag mode.
*/
return mIsBeingDragged;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
initVelocityTrackerIfNotExists();
MotionEvent vtev = MotionEvent.obtain(ev);
final int actionMasked = ev.getActionMasked();
if (actionMasked == MotionEvent.ACTION_DOWN) {
mNestedYOffset = 0;
}
vtev.offsetLocation(0, mNestedYOffset);
switch (actionMasked) {
case MotionEvent.ACTION_DOWN: {
if (getChildCount() == 0) {
return false;
}
if ((mIsBeingDragged = !mScroller.isFinished())) {
final ViewParent parent = getParent();
if (parent != null) {
parent.requestDisallowInterceptTouchEvent(true);
}
}
/*
* If being flinged and user touches, stop the fling. isFinished
* will be false if being flinged.
*/
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
if (mFlingStrictSpan != null) {
mFlingStrictSpan.finish();
mFlingStrictSpan = null;
}
}
// Remember where the motion event started
mLastMotionY = (int) ev.getY();
mActivePointerId = ev.getPointerId(0);
startNestedScroll(SCROLL_AXIS_VERTICAL);
break;
}
case MotionEvent.ACTION_MOVE:
final int activePointerIndex = ev.findPointerIndex(mActivePointerId);
if (activePointerIndex == -1) {
Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent");
break;
}
final int y = (int) ev.getY(activePointerIndex);
int deltaY = mLastMotionY - y;
if (dispatchNestedPreScroll(0, deltaY, mScrollConsumed, mScrollOffset)) {
deltaY -= mScrollConsumed[1];
vtev.offsetLocation(0, mScrollOffset[1]);
mNestedYOffset += mScrollOffset[1];
}
if (!mIsBeingDragged && Math.abs(deltaY) > mTouchSlop) {
final ViewParent parent = getParent();
if (parent != null) {
parent.requestDisallowInterceptTouchEvent(true);
}
mIsBeingDragged = true;
if (deltaY > 0) {
deltaY -= mTouchSlop;
} else {
deltaY += mTouchSlop;
}
}
if (mIsBeingDragged) {
// Scroll to follow the motion event
mLastMotionY = y - mScrollOffset[1];
final int oldY = mScrollY;
final int range = getScrollRange();
final int overscrollMode = getOverScrollMode();
boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS ||
(overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0);
// Calling overScrollBy will call onOverScrolled, which
// calls onScrollChanged if applicable.
if (overScrollBy(0, deltaY, 0, mScrollY, 0, range, 0, mOverscrollDistance, true)
&& !hasNestedScrollingParent()) {
// Break our velocity if we hit a scroll barrier.
mVelocityTracker.clear();
}
final int scrolledDeltaY = mScrollY - oldY;
final int unconsumedY = deltaY - scrolledDeltaY;
if (dispatchNestedScroll(0, scrolledDeltaY, 0, unconsumedY, mScrollOffset)) {
mLastMotionY -= mScrollOffset[1];
vtev.offsetLocation(0, mScrollOffset[1]);
mNestedYOffset += mScrollOffset[1];
} else if (canOverscroll) {
final int pulledToY = oldY + deltaY;
if (pulledToY < 0) {
mEdgeGlowTop.onPull((float) deltaY / getHeight(),
ev.getX(activePointerIndex) / getWidth());
if (!mEdgeGlowBottom.isFinished()) {
mEdgeGlowBottom.onRelease();
}
} else if (pulledToY > range) {
mEdgeGlowBottom.onPull((float) deltaY / getHeight(),
1.f - ev.getX(activePointerIndex) / getWidth());
if (!mEdgeGlowTop.isFinished()) {
mEdgeGlowTop.onRelease();
}
}
if (mEdgeGlowTop != null
&& (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) {
postInvalidateOnAnimation();
}
}
}
break;
case MotionEvent.ACTION_UP:
if (mIsBeingDragged) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId);
if ((Math.abs(initialVelocity) > mMinimumVelocity)) {
flingWithNestedDispatch(-initialVelocity);
} else if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0,
getScrollRange())) {
postInvalidateOnAnimation();
}
mActivePointerId = INVALID_POINTER;
endDrag();
}
break;
case MotionEvent.ACTION_CANCEL:
if (mIsBeingDragged && getChildCount() > 0) {
if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) {
postInvalidateOnAnimation();
}
mActivePointerId = INVALID_POINTER;
endDrag();
}
break;
case MotionEvent.ACTION_POINTER_DOWN: {
final int index = ev.getActionIndex();
mLastMotionY = (int) ev.getY(index);
mActivePointerId = ev.getPointerId(index);
break;
}
case MotionEvent.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
mLastMotionY = (int) ev.getY(ev.findPointerIndex(mActivePointerId));
break;
}
if (mVelocityTracker != null) {
mVelocityTracker.addMovement(vtev);
}
vtev.recycle();
return true;
}
private void onSecondaryPointerUp(MotionEvent ev) {
final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >>
MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
// This was our active pointer going up. Choose a new
// active pointer and adjust accordingly.
// TODO: Make this decision more intelligent.
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mLastMotionY = (int) ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
if (mVelocityTracker != null) {
mVelocityTracker.clear();
}
}
}
@Override
public boolean onGenericMotionEvent(MotionEvent event) {
if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) {
switch (event.getAction()) {
case MotionEvent.ACTION_SCROLL: {
if (!mIsBeingDragged) {
final float vscroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL);
if (vscroll != 0) {
final int delta = (int) (vscroll * getVerticalScrollFactor());
final int range = getScrollRange();
int oldScrollY = mScrollY;
int newScrollY = oldScrollY - delta;
if (newScrollY < 0) {
newScrollY = 0;
} else if (newScrollY > range) {
newScrollY = range;
}
if (newScrollY != oldScrollY) {
super.scrollTo(mScrollX, newScrollY);
return true;
}
}
}
}
}
}
return super.onGenericMotionEvent(event);
}
@Override
protected void onOverScrolled(int scrollX, int scrollY,
boolean clampedX, boolean clampedY) {
// Treat animating scrolls differently; see #computeScroll() for why.
if (!mScroller.isFinished()) {
final int oldX = mScrollX;
final int oldY = mScrollY;
mScrollX = scrollX;
mScrollY = scrollY;
invalidateParentIfNeeded();
onScrollChanged(mScrollX, mScrollY, oldX, oldY);
if (clampedY) {
mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange());
}
} else {
super.scrollTo(scrollX, scrollY);
}
awakenScrollBars();
}
@Override
public boolean performAccessibilityAction(int action, Bundle arguments) {
if (super.performAccessibilityAction(action, arguments)) {
return true;
}
if (!isEnabled()) {
return false;
}
switch (action) {
case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: {
final int viewportHeight = getHeight() - mPaddingBottom - mPaddingTop;
final int targetScrollY = Math.min(mScrollY + viewportHeight, getScrollRange());
if (targetScrollY != mScrollY) {
smoothScrollTo(0, targetScrollY);
return true;
}
} return false;
case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: {
final int viewportHeight = getHeight() - mPaddingBottom - mPaddingTop;
final int targetScrollY = Math.max(mScrollY - viewportHeight, 0);
if (targetScrollY != mScrollY) {
smoothScrollTo(0, targetScrollY);
return true;
}
} return false;
}
return false;
}
@Override
public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
super.onInitializeAccessibilityNodeInfo(info);
info.setClassName(ScrollView.class.getName());
if (isEnabled()) {
final int scrollRange = getScrollRange();
if (scrollRange > 0) {
info.setScrollable(true);
if (mScrollY > 0) {
info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD);
}
if (mScrollY < scrollRange) {
info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD);
}
}
}
}
@Override
public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
super.onInitializeAccessibilityEvent(event);
event.setClassName(ScrollView.class.getName());
final boolean scrollable = getScrollRange() > 0;
event.setScrollable(scrollable);
event.setScrollX(mScrollX);
event.setScrollY(mScrollY);
event.setMaxScrollX(mScrollX);
event.setMaxScrollY(getScrollRange());
}
private int getScrollRange() {
int scrollRange = 0;
if (getChildCount() > 0) {
View child = getChildAt(0);
scrollRange = Math.max(0,
child.getHeight() - (getHeight() - mPaddingBottom - mPaddingTop));
}
return scrollRange;
}
/**
* <p>
* Finds the next focusable component that fits in the specified bounds.
* </p>
*
* @param topFocus look for a candidate is the one at the top of the bounds
* if topFocus is true, or at the bottom of the bounds if topFocus is
* false
* @param top the top offset of the bounds in which a focusable must be
* found
* @param bottom the bottom offset of the bounds in which a focusable must
* be found
* @return the next focusable component in the bounds or null if none can
* be found
*/
private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) {
List<View> focusables = getFocusables(View.FOCUS_FORWARD);
View focusCandidate = null;
/*
* A fully contained focusable is one where its top is below the bound's
* top, and its bottom is above the bound's bottom. A partially
* contained focusable is one where some part of it is within the
* bounds, but it also has some part that is not within bounds. A fully contained
* focusable is preferred to a partially contained focusable.
*/
boolean foundFullyContainedFocusable = false;
int count = focusables.size();
for (int i = 0; i < count; i++) {
View view = focusables.get(i);
int viewTop = view.getTop();
int viewBottom = view.getBottom();
if (top < viewBottom && viewTop < bottom) {
/*
* the focusable is in the target area, it is a candidate for
* focusing
*/
final boolean viewIsFullyContained = (top < viewTop) &&
(viewBottom < bottom);
if (focusCandidate == null) {
/* No candidate, take this one */
focusCandidate = view;
foundFullyContainedFocusable = viewIsFullyContained;
} else {
final boolean viewIsCloserToBoundary =
(topFocus && viewTop < focusCandidate.getTop()) ||
(!topFocus && viewBottom > focusCandidate
.getBottom());
if (foundFullyContainedFocusable) {
if (viewIsFullyContained && viewIsCloserToBoundary) {
/*
* We're dealing with only fully contained views, so
* it has to be closer to the boundary to beat our
* candidate
*/
focusCandidate = view;
}
} else {
if (viewIsFullyContained) {
/* Any fully contained view beats a partially contained view */
focusCandidate = view;
foundFullyContainedFocusable = true;
} else if (viewIsCloserToBoundary) {
/*
* Partially contained view beats another partially
* contained view if it's closer
*/
focusCandidate = view;
}
}
}
}
}
return focusCandidate;
}
/**
* <p>Handles scrolling in response to a "page up/down" shortcut press. This
* method will scroll the view by one page up or down and give the focus
* to the topmost/bottommost component in the new visible area. If no
* component is a good candidate for focus, this scrollview reclaims the
* focus.</p>
*
* @param direction the scroll direction: {@link android.view.View#FOCUS_UP}
* to go one page up or
* {@link android.view.View#FOCUS_DOWN} to go one page down
* @return true if the key event is consumed by this method, false otherwise
*/
public boolean pageScroll(int direction) {
boolean down = direction == View.FOCUS_DOWN;
int height = getHeight();
if (down) {
mTempRect.top = getScrollY() + height;
int count = getChildCount();
if (count > 0) {
View view = getChildAt(count - 1);
if (mTempRect.top + height > view.getBottom()) {
mTempRect.top = view.getBottom() - height;
}
}
} else {
mTempRect.top = getScrollY() - height;
if (mTempRect.top < 0) {
mTempRect.top = 0;
}
}
mTempRect.bottom = mTempRect.top + height;
return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom);
}
/**
* <p>Handles scrolling in response to a "home/end" shortcut press. This
* method will scroll the view to the top or bottom and give the focus
* to the topmost/bottommost component in the new visible area. If no
* component is a good candidate for focus, this scrollview reclaims the
* focus.</p>
*
* @param direction the scroll direction: {@link android.view.View#FOCUS_UP}
* to go the top of the view or
* {@link android.view.View#FOCUS_DOWN} to go the bottom
* @return true if the key event is consumed by this method, false otherwise
*/
public boolean fullScroll(int direction) {
boolean down = direction == View.FOCUS_DOWN;
int height = getHeight();
mTempRect.top = 0;
mTempRect.bottom = height;
if (down) {
int count = getChildCount();
if (count > 0) {
View view = getChildAt(count - 1);
mTempRect.bottom = view.getBottom() + mPaddingBottom;
mTempRect.top = mTempRect.bottom - height;
}
}
return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom);
}
/**
* <p>Scrolls the view to make the area defined by <code>top</code> and
* <code>bottom</code> visible. This method attempts to give the focus
* to a component visible in this area. If no component can be focused in
* the new visible area, the focus is reclaimed by this ScrollView.</p>
*
* @param direction the scroll direction: {@link android.view.View#FOCUS_UP}
* to go upward, {@link android.view.View#FOCUS_DOWN} to downward
* @param top the top offset of the new area to be made visible
* @param bottom the bottom offset of the new area to be made visible
* @return true if the key event is consumed by this method, false otherwise
*/
private boolean scrollAndFocus(int direction, int top, int bottom) {
boolean handled = true;
int height = getHeight();
int containerTop = getScrollY();
int containerBottom = containerTop + height;
boolean up = direction == View.FOCUS_UP;
View newFocused = findFocusableViewInBounds(up, top, bottom);
if (newFocused == null) {
newFocused = this;
}
if (top >= containerTop && bottom <= containerBottom) {
handled = false;
} else {
int delta = up ? (top - containerTop) : (bottom - containerBottom);
doScrollY(delta);
}
if (newFocused != findFocus()) newFocused.requestFocus(direction);
return handled;
}
/**
* Handle scrolling in response to an up or down arrow click.
*
* @param direction The direction corresponding to the arrow key that was
* pressed
* @return True if we consumed the event, false otherwise
*/
public boolean arrowScroll(int direction) {
View currentFocused = findFocus();
if (currentFocused == this) currentFocused = null;
View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction);
final int maxJump = getMaxScrollAmount();
if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) {
nextFocused.getDrawingRect(mTempRect);
offsetDescendantRectToMyCoords(nextFocused, mTempRect);
int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
doScrollY(scrollDelta);
nextFocused.requestFocus(direction);
} else {
// no new focus
int scrollDelta = maxJump;
if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) {
scrollDelta = getScrollY();
} else if (direction == View.FOCUS_DOWN) {
if (getChildCount() > 0) {
int daBottom = getChildAt(0).getBottom();
int screenBottom = getScrollY() + getHeight() - mPaddingBottom;
if (daBottom - screenBottom < maxJump) {
scrollDelta = daBottom - screenBottom;
}
}
}
if (scrollDelta == 0) {
return false;
}
doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta);
}
if (currentFocused != null && currentFocused.isFocused()
&& isOffScreen(currentFocused)) {
// previously focused item still has focus and is off screen, give
// it up (take it back to ourselves)
// (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are
// sure to
// get it)
final int descendantFocusability = getDescendantFocusability(); // save
setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS);
requestFocus();
setDescendantFocusability(descendantFocusability); // restore
}
return true;
}
/**
* @return whether the descendant of this scroll view is scrolled off
* screen.
*/
private boolean isOffScreen(View descendant) {
return !isWithinDeltaOfScreen(descendant, 0, getHeight());
}
/**
* @return whether the descendant of this scroll view is within delta
* pixels of being on the screen.
*/
private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) {
descendant.getDrawingRect(mTempRect);
offsetDescendantRectToMyCoords(descendant, mTempRect);
return (mTempRect.bottom + delta) >= getScrollY()
&& (mTempRect.top - delta) <= (getScrollY() + height);
}
/**
* Smooth scroll by a Y delta
*
* @param delta the number of pixels to scroll by on the Y axis
*/
private void doScrollY(int delta) {
if (delta != 0) {
if (mSmoothScrollingEnabled) {
smoothScrollBy(0, delta);
} else {
scrollBy(0, delta);
}
}
}
/**
* Like {@link View#scrollBy}, but scroll smoothly instead of immediately.
*
* @param dx the number of pixels to scroll by on the X axis
* @param dy the number of pixels to scroll by on the Y axis
*/
public final void smoothScrollBy(int dx, int dy) {
if (getChildCount() == 0) {
// Nothing to do.
return;
}
long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll;
if (duration > ANIMATED_SCROLL_GAP) {
final int height = getHeight() - mPaddingBottom - mPaddingTop;
final int bottom = getChildAt(0).getHeight();
final int maxY = Math.max(0, bottom - height);
final int scrollY = mScrollY;
dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY;
mScroller.startScroll(mScrollX, scrollY, 0, dy);
postInvalidateOnAnimation();
} else {
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
if (mFlingStrictSpan != null) {
mFlingStrictSpan.finish();
mFlingStrictSpan = null;
}
}
scrollBy(dx, dy);
}
mLastScroll = AnimationUtils.currentAnimationTimeMillis();
}
/**
* Like {@link #scrollTo}, but scroll smoothly instead of immediately.
*
* @param x the position where to scroll on the X axis
* @param y the position where to scroll on the Y axis
*/
public final void smoothScrollTo(int x, int y) {
smoothScrollBy(x - mScrollX, y - mScrollY);
}
/**
* <p>The scroll range of a scroll view is the overall height of all of its
* children.</p>
*/
@Override
protected int computeVerticalScrollRange() {
final int count = getChildCount();
final int contentHeight = getHeight() - mPaddingBottom - mPaddingTop;
if (count == 0) {
return contentHeight;
}
int scrollRange = getChildAt(0).getBottom();
final int scrollY = mScrollY;
final int overscrollBottom = Math.max(0, scrollRange - contentHeight);
if (scrollY < 0) {
scrollRange -= scrollY;
} else if (scrollY > overscrollBottom) {
scrollRange += scrollY - overscrollBottom;
}
return scrollRange;
}
@Override
protected int computeVerticalScrollOffset() {
return Math.max(0, super.computeVerticalScrollOffset());
}
@Override
protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) {
ViewGroup.LayoutParams lp = child.getLayoutParams();
int childWidthMeasureSpec;
int childHeightMeasureSpec;
childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, mPaddingLeft
+ mPaddingRight, lp.width);
childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
@Override
protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed,
int parentHeightMeasureSpec, int heightUsed) {
final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec,
mPaddingLeft + mPaddingRight + lp.leftMargin + lp.rightMargin
+ widthUsed, lp.width);
final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED);
child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
@Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) {
// This is called at drawing time by ViewGroup. We don't want to
// re-show the scrollbars at this point, which scrollTo will do,
// so we replicate most of scrollTo here.
//
// It's a little odd to call onScrollChanged from inside the drawing.
//
// It is, except when you remember that computeScroll() is used to
// animate scrolling. So unless we want to defer the onScrollChanged()
// until the end of the animated scrolling, we don't really have a
// choice here.
//
// I agree. The alternative, which I think would be worse, is to post
// something and tell the subclasses later. This is bad because there
// will be a window where mScrollX/Y is different from what the app
// thinks it is.
//
int oldX = mScrollX;
int oldY = mScrollY;
int x = mScroller.getCurrX();
int y = mScroller.getCurrY();
if (oldX != x || oldY != y) {
final int range = getScrollRange();
final int overscrollMode = getOverScrollMode();
final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS ||
(overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0);
overScrollBy(x - oldX, y - oldY, oldX, oldY, 0, range,
0, mOverflingDistance, false);
onScrollChanged(mScrollX, mScrollY, oldX, oldY);
if (canOverscroll) {
if (y < 0 && oldY >= 0) {
mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity());
} else if (y > range && oldY <= range) {
mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity());
}
}
}
if (!awakenScrollBars()) {
// Keep on drawing until the animation has finished.
postInvalidateOnAnimation();
}
} else {
if (mFlingStrictSpan != null) {
mFlingStrictSpan.finish();
mFlingStrictSpan = null;
}
}
}
/**
* Scrolls the view to the given child.
*
* @param child the View to scroll to
*/
private void scrollToChild(View child) {
child.getDrawingRect(mTempRect);
/* Offset from child's local coordinates to ScrollView coordinates */
offsetDescendantRectToMyCoords(child, mTempRect);
int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
if (scrollDelta != 0) {
scrollBy(0, scrollDelta);
}
}
/**
* If rect is off screen, scroll just enough to get it (or at least the
* first screen size chunk of it) on screen.
*
* @param rect The rectangle.
* @param immediate True to scroll immediately without animation
* @return true if scrolling was performed
*/
private boolean scrollToChildRect(Rect rect, boolean immediate) {
final int delta = computeScrollDeltaToGetChildRectOnScreen(rect);
final boolean scroll = delta != 0;
if (scroll) {
if (immediate) {
scrollBy(0, delta);
} else {
smoothScrollBy(0, delta);
}
}
return scroll;
}
/**
* Compute the amount to scroll in the Y direction in order to get
* a rectangle completely on the screen (or, if taller than the screen,
* at least the first screen size chunk of it).
*
* @param rect The rect.
* @return The scroll delta.
*/
protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) {
if (getChildCount() == 0) return 0;
int height = getHeight();
int screenTop = getScrollY();
int screenBottom = screenTop + height;
int fadingEdge = getVerticalFadingEdgeLength();
// leave room for top fading edge as long as rect isn't at very top
if (rect.top > 0) {
screenTop += fadingEdge;
}
// leave room for bottom fading edge as long as rect isn't at very bottom
if (rect.bottom < getChildAt(0).getHeight()) {
screenBottom -= fadingEdge;
}
int scrollYDelta = 0;
if (rect.bottom > screenBottom && rect.top > screenTop) {
// need to move down to get it in view: move down just enough so
// that the entire rectangle is in view (or at least the first
// screen size chunk).
if (rect.height() > height) {
// just enough to get screen size chunk on
scrollYDelta += (rect.top - screenTop);
} else {
// get entire rect at bottom of screen
scrollYDelta += (rect.bottom - screenBottom);
}
// make sure we aren't scrolling beyond the end of our content
int bottom = getChildAt(0).getBottom();
int distanceToBottom = bottom - screenBottom;
scrollYDelta = Math.min(scrollYDelta, distanceToBottom);
} else if (rect.top < screenTop && rect.bottom < screenBottom) {
// need to move up to get it in view: move up just enough so that
// entire rectangle is in view (or at least the first screen
// size chunk of it).
if (rect.height() > height) {
// screen size chunk
scrollYDelta -= (screenBottom - rect.bottom);
} else {
// entire rect at top
scrollYDelta -= (screenTop - rect.top);
}
// make sure we aren't scrolling any further than the top our content
scrollYDelta = Math.max(scrollYDelta, -getScrollY());
}
return scrollYDelta;
}
@Override
public void requestChildFocus(View child, View focused) {
if (!mIsLayoutDirty) {
scrollToChild(focused);
} else {
// The child may not be laid out yet, we can't compute the scroll yet
mChildToScrollTo = focused;
}
super.requestChildFocus(child, focused);
}
/**
* When looking for focus in children of a scroll view, need to be a little
* more careful not to give focus to something that is scrolled off screen.
*
* This is more expensive than the default {@link android.view.ViewGroup}
* implementation, otherwise this behavior might have been made the default.
*/
@Override
protected boolean onRequestFocusInDescendants(int direction,
Rect previouslyFocusedRect) {
// convert from forward / backward notation to up / down / left / right
// (ugh).
if (direction == View.FOCUS_FORWARD) {
direction = View.FOCUS_DOWN;
} else if (direction == View.FOCUS_BACKWARD) {
direction = View.FOCUS_UP;
}
final View nextFocus = previouslyFocusedRect == null ?
FocusFinder.getInstance().findNextFocus(this, null, direction) :
FocusFinder.getInstance().findNextFocusFromRect(this,
previouslyFocusedRect, direction);
if (nextFocus == null) {
return false;
}
if (isOffScreen(nextFocus)) {
return false;
}
return nextFocus.requestFocus(direction, previouslyFocusedRect);
}
@Override
public boolean requestChildRectangleOnScreen(View child, Rect rectangle,
boolean immediate) {
// offset into coordinate space of this scroll view
rectangle.offset(child.getLeft() - child.getScrollX(),
child.getTop() - child.getScrollY());
return scrollToChildRect(rectangle, immediate);
}
@Override
public void requestLayout() {
mIsLayoutDirty = true;
super.requestLayout();
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
if (mScrollStrictSpan != null) {
mScrollStrictSpan.finish();
mScrollStrictSpan = null;
}
if (mFlingStrictSpan != null) {
mFlingStrictSpan.finish();
mFlingStrictSpan = null;
}
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
mIsLayoutDirty = false;
// Give a child focus if it needs it
if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) {
scrollToChild(mChildToScrollTo);
}
mChildToScrollTo = null;
if (!isLaidOut()) {
if (mSavedState != null) {
mScrollY = mSavedState.scrollPosition;
mSavedState = null;
} // mScrollY default value is "0"
final int childHeight = (getChildCount() > 0) ? getChildAt(0).getMeasuredHeight() : 0;
final int scrollRange = Math.max(0,
childHeight - (b - t - mPaddingBottom - mPaddingTop));
// Don't forget to clamp
if (mScrollY > scrollRange) {
mScrollY = scrollRange;
} else if (mScrollY < 0) {
mScrollY = 0;
}
}
// Calling this with the present values causes it to re-claim them
scrollTo(mScrollX, mScrollY);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
View currentFocused = findFocus();
if (null == currentFocused || this == currentFocused)
return;
// If the currently-focused view was visible on the screen when the
// screen was at the old height, then scroll the screen to make that
// view visible with the new screen height.
if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) {
currentFocused.getDrawingRect(mTempRect);
offsetDescendantRectToMyCoords(currentFocused, mTempRect);
int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
doScrollY(scrollDelta);
}
}
/**
* Return true if child is a descendant of parent, (or equal to the parent).
*/
private static boolean isViewDescendantOf(View child, View parent) {
if (child == parent) {
return true;
}
final ViewParent theParent = child.getParent();
return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent);
}
/**
* Fling the scroll view
*
* @param velocityY The initial velocity in the Y direction. Positive
* numbers mean that the finger/cursor is moving down the screen,
* which means we want to scroll towards the top.
*/
public void fling(int velocityY) {
if (getChildCount() > 0) {
int height = getHeight() - mPaddingBottom - mPaddingTop;
int bottom = getChildAt(0).getHeight();
mScroller.fling(mScrollX, mScrollY, 0, velocityY, 0, 0, 0,
Math.max(0, bottom - height), 0, height/2);
if (mFlingStrictSpan == null) {
mFlingStrictSpan = StrictMode.enterCriticalSpan("ScrollView-fling");
}
postInvalidateOnAnimation();
}
}
private void flingWithNestedDispatch(int velocityY) {
final boolean canFling = (mScrollY > 0 || velocityY > 0) &&
(mScrollY < getScrollRange() || velocityY < 0);
if (!dispatchNestedPreFling(0, velocityY)) {
dispatchNestedFling(0, velocityY, canFling);
if (canFling) {
fling(velocityY);
}
}
}
private void endDrag() {
mIsBeingDragged = false;
recycleVelocityTracker();
if (mEdgeGlowTop != null) {
mEdgeGlowTop.onRelease();
mEdgeGlowBottom.onRelease();
}
if (mScrollStrictSpan != null) {
mScrollStrictSpan.finish();
mScrollStrictSpan = null;
}
}
/**
* {@inheritDoc}
*
* <p>This version also clamps the scrolling to the bounds of our child.
*/
@Override
public void scrollTo(int x, int y) {
// we rely on the fact the View.scrollBy calls scrollTo.
if (getChildCount() > 0) {
View child = getChildAt(0);
x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth());
y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight());
if (x != mScrollX || y != mScrollY) {
super.scrollTo(x, y);
}
}
}
@Override
public void setOverScrollMode(int mode) {
if (mode != OVER_SCROLL_NEVER) {
if (mEdgeGlowTop == null) {
Context context = getContext();
mEdgeGlowTop = new EdgeEffect(context);
mEdgeGlowBottom = new EdgeEffect(context);
}
} else {
mEdgeGlowTop = null;
mEdgeGlowBottom = null;
}
super.setOverScrollMode(mode);
}
@Override
public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) {
return (nestedScrollAxes & SCROLL_AXIS_VERTICAL) != 0;
}
@Override
public void onNestedScrollAccepted(View child, View target, int axes) {
super.onNestedScrollAccepted(child, target, axes);
startNestedScroll(SCROLL_AXIS_VERTICAL);
}
/**
* @inheritDoc
*/
@Override
public void onStopNestedScroll(View target) {
super.onStopNestedScroll(target);
}
@Override
public void onNestedScroll(View target, int dxConsumed, int dyConsumed,
int dxUnconsumed, int dyUnconsumed) {
final int oldScrollY = mScrollY;
scrollBy(0, dyUnconsumed);
final int myConsumed = mScrollY - oldScrollY;
final int myUnconsumed = dyUnconsumed - myConsumed;
dispatchNestedScroll(0, myConsumed, 0, myUnconsumed, null);
}
/**
* @inheritDoc
*/
@Override
public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed) {
if (!consumed) {
flingWithNestedDispatch((int) velocityY);
return true;
}
return false;
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
if (mEdgeGlowTop != null) {
final int scrollY = mScrollY;
if (!mEdgeGlowTop.isFinished()) {
final int restoreCount = canvas.save();
final int width = getWidth() - mPaddingLeft - mPaddingRight;
canvas.translate(mPaddingLeft, Math.min(0, scrollY));
mEdgeGlowTop.setSize(width, getHeight());
if (mEdgeGlowTop.draw(canvas)) {
postInvalidateOnAnimation();
}
canvas.restoreToCount(restoreCount);
}
if (!mEdgeGlowBottom.isFinished()) {
final int restoreCount = canvas.save();
final int width = getWidth() - mPaddingLeft - mPaddingRight;
final int height = getHeight();
canvas.translate(-width + mPaddingLeft,
Math.max(getScrollRange(), scrollY) + height);
canvas.rotate(180, width, 0);
mEdgeGlowBottom.setSize(width, height);
if (mEdgeGlowBottom.draw(canvas)) {
postInvalidateOnAnimation();
}
canvas.restoreToCount(restoreCount);
}
}
}
private static int clamp(int n, int my, int child) {
if (my >= child || n < 0) {
/* my >= child is this case:
* |--------------- me ---------------|
* |------ child ------|
* or
* |--------------- me ---------------|
* |------ child ------|
* or
* |--------------- me ---------------|
* |------ child ------|
*
* n < 0 is this case:
* |------ me ------|
* |-------- child --------|
* |-- mScrollX --|
*/
return 0;
}
if ((my+n) > child) {
/* this case:
* |------ me ------|
* |------ child ------|
* |-- mScrollX --|
*/
return child-my;
}
return n;
}
@Override
protected void onRestoreInstanceState(Parcelable state) {
if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) {
// Some old apps reused IDs in ways they shouldn't have.
// Don't break them, but they don't get scroll state restoration.
super.onRestoreInstanceState(state);
return;
}
SavedState ss = (SavedState) state;
super.onRestoreInstanceState(ss.getSuperState());
mSavedState = ss;
requestLayout();
}
@Override
protected Parcelable onSaveInstanceState() {
if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) {
// Some old apps reused IDs in ways they shouldn't have.
// Don't break them, but they don't get scroll state restoration.
return super.onSaveInstanceState();
}
Parcelable superState = super.onSaveInstanceState();
SavedState ss = new SavedState(superState);
ss.scrollPosition = mScrollY;
return ss;
}
static class SavedState extends BaseSavedState {
public int scrollPosition;
SavedState(Parcelable superState) {
super(superState);
}
public SavedState(Parcel source) {
super(source);
scrollPosition = source.readInt();
}
@Override
public void writeToParcel(Parcel dest, int flags) {
super.writeToParcel(dest, flags);
dest.writeInt(scrollPosition);
}
@Override
public String toString() {
return "HorizontalScrollView.SavedState{"
+ Integer.toHexString(System.identityHashCode(this))
+ " scrollPosition=" + scrollPosition + "}";
}
public static final Parcelable.Creator<SavedState> CREATOR
= new Parcelable.Creator<SavedState>() {
public SavedState createFromParcel(Parcel in) {
return new SavedState(in);
}
public SavedState[] newArray(int size) {
return new SavedState[size];
}
};
}
}
|
