/*
* Copyright (C) 2008 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.view;
import android.graphics.Rect;
import java.util.concurrent.CopyOnWriteArrayList;
/**
* A view tree observer is used to register listeners that can be notified of global
* changes in the view tree. Such global events include, but are not limited to,
* layout of the whole tree, beginning of the drawing pass, touch mode change....
*
* A ViewTreeObserver should never be instantiated by applications as it is provided
* by the views hierarchy. Refer to {@link android.view.View#getViewTreeObserver()}
* for more information.
*/
public final class ViewTreeObserver {
private CopyOnWriteArrayList<OnGlobalFocusChangeListener> mOnGlobalFocusListeners;
private CopyOnWriteArrayList<OnGlobalLayoutListener> mOnGlobalLayoutListeners;
private CopyOnWriteArrayList<OnPreDrawListener> mOnPreDrawListeners;
private CopyOnWriteArrayList<OnTouchModeChangeListener> mOnTouchModeChangeListeners;
private CopyOnWriteArrayList<OnComputeInternalInsetsListener> mOnComputeInternalInsetsListeners;
private CopyOnWriteArrayList<OnScrollChangedListener> mOnScrollChangedListeners;
private boolean mAlive = true;
/**
* Interface definition for a callback to be invoked when the focus state within
* the view tree changes.
*/
public interface OnGlobalFocusChangeListener {
/**
* Callback method to be invoked when the focus changes in the view tree. When
* the view tree transitions from touch mode to non-touch mode, oldFocus is null.
* When the view tree transitions from non-touch mode to touch mode, newFocus is
* null. When focus changes in non-touch mode (without transition from or to
* touch mode) either oldFocus or newFocus can be null.
*
* @param oldFocus The previously focused view, if any.
* @param newFocus The newly focused View, if any.
*/
public void onGlobalFocusChanged(View oldFocus, View newFocus);
}
/**
* Interface definition for a callback to be invoked when the global layout state
* or the visibility of views within the view tree changes.
*/
public interface OnGlobalLayoutListener {
/**
* Callback method to be invoked when the global layout state or the visibility of views
* within the view tree changes
*/
public void onGlobalLayout();
}
/**
* Interface definition for a callback to be invoked when the view tree is about to be drawn.
*/
public interface OnPreDrawListener {
/**
* Callback method to be invoked when the view tree is about to be drawn. At this point, all
* views in the tree have been measured and given a frame. Clients can use this to adjust
* their scroll bounds or even to request a new layout before drawing occurs.
*
* @return Return true to proceed with the current drawing pass, or false to cancel.
*
* @see android.view.View#onMeasure
* @see android.view.View#onLayout
* @see android.view.View#onDraw
*/
public boolean onPreDraw();
}
/**
* Interface definition for a callback to be invoked when the touch mode changes.
*/
public interface OnTouchModeChangeListener {
/**
* Callback method to be invoked when the touch mode changes.
*
* @param isInTouchMode True if the view hierarchy is now in touch mode, false otherwise.
*/
public void onTouchModeChanged(boolean isInTouchMode);
}
/**
* Interface definition for a callback to be invoked when
* something in the view tree has been scrolled.
*/
public interface OnScrollChangedListener {
/**
* Callback method to be invoked when something in the view tree
* has been scrolled.
*/
public void onScrollChanged();
}
/**
* Parameters used with OnComputeInternalInsetsListener.
*
* We are not yet ready to commit to this API and support it, so
* @hide
*/
public final static class InternalInsetsInfo {
/**
* Offsets from the frame of the window at which the content of
* windows behind it should be placed.
*/
public final Rect contentInsets = new Rect();
/**
* Offsets from the fram of the window at which windows behind it
* are visible.
*/
public final Rect visibleInsets = new Rect();
/**
* Option for {@link #setTouchableInsets(int)}: the entire window frame
* can be touched.
*/
public static final int TOUCHABLE_INSETS_FRAME = 0;
/**
* Option for {@link #setTouchableInsets(int)}: the area inside of
* the content insets can be touched.
*/
public static final int TOUCHABLE_INSETS_CONTENT = 1;
/**
* Option for {@link #setTouchableInsets(int)}: the area inside of
* the visible insets can be touched.
*/
public static final int TOUCHABLE_INSETS_VISIBLE = 2;
/**
* Set which parts of the window can be touched: either
* {@link #TOUCHABLE_INSETS_FRAME}, {@link #TOUCHABLE_INSETS_CONTENT},
* or {@link #TOUCHABLE_INSETS_VISIBLE}.
*/
public void setTouchableInsets(int val) {
mTouchableInsets = val;
}
public int getTouchableInsets() {
return mTouchableInsets;
}
int mTouchableInsets;
void reset() {
final Rect givenContent = contentInsets;
final Rect givenVisible = visibleInsets;
givenContent.left = givenContent.top = givenContent.right
= givenContent.bottom = givenVisible.left = givenVisible.top
= givenVisible.right = givenVisible.bottom = 0;
mTouchableInsets = TOUCHABLE_INSETS_FRAME;
}
@Override public boolean equals(Object o) {
try {
if (o == null) {
return false;
}
InternalInsetsInfo other = (InternalInsetsInfo)o;
if (!contentInsets.equals(other.contentInsets)) {
return false;
}
if (!visibleInsets.equals(other.visibleInsets)) {
return false;
}
return mTouchableInsets == other.mTouchableInsets;
} catch (ClassCastException e) {
return false;
}
}
void set(InternalInsetsInfo other) {
contentInsets.set(other.contentInsets);
visibleInsets.set(other.visibleInsets);
mTouchableInsets = other.mTouchableInsets;
}
}
/**
* Interface definition for a callback to be invoked when layout has
* completed and the client can compute its interior insets.
*
* We are not yet ready to commit to this API and support it, so
* @hide
*/
public interface OnComputeInternalInsetsListener {
/**
* Callback method to be invoked when layout has completed and the
* client can compute its interior insets.
*
* @param inoutInfo Should be filled in by the implementation with
* the information about the insets of the window. This is called
* with whatever values the previous OnComputeInternalInsetsListener
* returned, if there are multiple such listeners in the window.
*/
public void onComputeInternalInsets(InternalInsetsInfo inoutInfo);
}
/**
* Creates a new ViewTreeObserver. This constructor should not be called
*/
ViewTreeObserver() {
}
/**
* Merges all the listeners registered on the specified observer with the listeners
* registered on this object. After this method is invoked, the specified observer
* will return false in {@link #isAlive()} and should not be used anymore.
*
* @param observer The ViewTreeObserver whose listeners must be added to this observer
*/
void merge(ViewTreeObserver observer) {
if (observer.mOnGlobalFocusListeners != null) {
if (mOnGlobalFocusListeners != null) {
mOnGlobalFocusListeners.addAll(observer.mOnGlobalFocusListeners);
} else {
mOnGlobalFocusListeners = observer.mOnGlobalFocusListeners;
}
}
if (observer.mOnGlobalLayoutListeners != null) {
if (mOnGlobalLayoutListeners != null) {
mOnGlobalLayoutListeners.addAll(observer.mOnGlobalLayoutListeners);
} else {
mOnGlobalLayoutListeners = observer.mOnGlobalLayoutListeners;
}
}
if (observer.mOnPreDrawListeners != null) {
if (mOnPreDrawListeners != null) {
mOnPreDrawListeners.addAll(observer.mOnPreDrawListeners);
} else {
mOnPreDrawListeners = observer.mOnPreDrawListeners;
}
}
if (observer.mOnTouchModeChangeListeners != null) {
if (mOnTouchModeChangeListeners != null) {
mOnTouchModeChangeListeners.addAll(observer.mOnTouchModeChangeListeners);
} else {
mOnTouchModeChangeListeners = observer.mOnTouchModeChangeListeners;
}
}
if (observer.mOnComputeInternalInsetsListeners != null) {
if (mOnComputeInternalInsetsListeners != null) {
mOnComputeInternalInsetsListeners.addAll(observer.mOnComputeInternalInsetsListeners);
} else {
mOnComputeInternalInsetsListeners = observer.mOnComputeInternalInsetsListeners;
}
}
observer.kill();
}
/**
* Register a callback to be invoked when the focus state within the view tree changes.
*
* @param listener The callback to add
*
* @throws IllegalStateException If {@link #isAlive()} returns false
*/
public void addOnGlobalFocusChangeListener(OnGlobalFocusChangeListener listener) {
checkIsAlive();
if (mOnGlobalFocusListeners == null) {
mOnGlobalFocusListeners = new CopyOnWriteArrayList<OnGlobalFocusChangeListener>();
}
mOnGlobalFocusListeners.add(listener);
}
/**
* Remove a previously installed focus change callback.
*
* @param victim The callback to remove
*
* @throws IllegalStateException If {@link #isAlive()} returns false
*
* @see #addOnGlobalFocusChangeListener(OnGlobalFocusChangeListener)
*/
public void removeOnGlobalFocusChangeListener(OnGlobalFocusChangeListener victim) {
checkIsAlive();
if (mOnGlobalFocusListeners == null) {
return;
}
mOnGlobalFocusListeners.remove(victim);
}
/**
* Register a callback to be invoked when the global layout state or the visibility of views
* within the view tree changes
*
* @param listener The callback to add
*
* @throws IllegalStateException If {@link #isAlive()} returns false
*/
public void addOnGlobalLayoutListener(OnGlobalLayoutListener listener) {
checkIsAlive();
if (mOnGlobalLayoutListeners == null) {
mOnGlobalLayoutListeners = new CopyOnWriteArrayList<OnGlobalLayoutListener>();
}
mOnGlobalLayoutListeners.add(listener);
}
/**
* Remove a previously installed global layout callback
*
* @param victim The callback to remove
*
* @throws IllegalStateException If {@link #isAlive()} returns false
*
* @see #addOnGlobalLayoutListener(OnGlobalLayoutListener)
*/
public void removeGlobalOnLayoutListener(OnGlobalLayoutListener victim) {
checkIsAlive();
if (mOnGlobalLayoutListeners == null) {
return;
}
mOnGlobalLayoutListeners.remove(victim);
}
/**
* Register a callback to be invoked when the view tree is about to be drawn
*
* @param listener The callback to add
*
* @throws IllegalStateException If {@link #isAlive()} returns false
*/
public void addOnPreDrawListener(OnPreDrawListener listener) {
checkIsAlive();
if (mOnPreDrawListeners == null) {
mOnPreDrawListeners = new CopyOnWriteArrayList<OnPreDrawListener>();
}
mOnPreDrawListeners.add(listener);
}
/**
* Remove a previously installed pre-draw callback
*
* @param victim The callback to remove
*
* @throws IllegalStateException If {@link #isAlive()} returns false
*
* @see #addOnPreDrawListener(OnPreDrawListener)
*/
public void removeOnPreDrawListener(OnPreDrawListener victim) {
checkIsAlive();
if (mOnPreDrawListeners == null) {
return;
}
mOnPreDrawListeners.remove(victim);
}
/**
* Register a callback to be invoked when a view has been scrolled.
*
* @param listener The callback to add
*
* @throws IllegalStateException If {@link #isAlive()} returns false
*/
public void addOnScrollChangedListener(OnScrollChangedListener listener) {
checkIsAlive();
if (mOnScrollChangedListeners == null) {
mOnScrollChangedListeners = new CopyOnWriteArrayList<OnScrollChangedListener>();
}
mOnScrollChangedListeners.add(listener);
}
/**
* Remove a previously installed scroll-changed callback
*
* @param victim The callback to remove
*
* @throws IllegalStateException If {@link #isAlive()} returns false
*
* @see #addOnScrollChangedListener(OnScrollChangedListener)
*/
public void removeOnScrollChangedListener(OnScrollChangedListener victim) {
checkIsAlive();
if (mOnScrollChangedListeners == null) {
return;
}
mOnScrollChangedListeners.remove(victim);
}
/**
* Register a callback to be invoked when the invoked when the touch mode changes.
*
* @param listener The callback to add
*
* @throws IllegalStateException If {@link #isAlive()} returns false
*/
public void addOnTouchModeChangeListener(OnTouchModeChangeListener listener) {
checkIsAlive();
if (mOnTouchModeChangeListeners == null) {
mOnTouchModeChangeListeners = new CopyOnWriteArrayList<OnTouchModeChangeListener>();
}
mOnTouchModeChangeListeners.add(listener);
}
/**
* Remove a previously installed touch mode change callback
*
* @param victim The callback to remove
*
* @throws IllegalStateException If {@link #isAlive()} returns false
*
* @see #addOnTouchModeChangeListener(OnTouchModeChangeListener)
*/
public void removeOnTouchModeChangeListener(OnTouchModeChangeListener victim) {
checkIsAlive();
if (mOnTouchModeChangeListeners == null) {
return;
}
mOnTouchModeChangeListeners.remove(victim);
}
/**
* Register a callback to be invoked when the invoked when it is time to
* compute the window's internal insets.
*
* @param listener The callback to add
*
* @throws IllegalStateException If {@link #isAlive()} returns false
*
* We are not yet ready to commit to this API and support it, so
* @hide
*/
public void addOnComputeInternalInsetsListener(OnComputeInternalInsetsListener listener) {
checkIsAlive();
if (mOnComputeInternalInsetsListeners == null) {
mOnComputeInternalInsetsListeners =
new CopyOnWriteArrayList<OnComputeInternalInsetsListener>();
}
mOnComputeInternalInsetsListeners.add(listener);
}
/**
* Remove a previously installed internal insets computation callback
*
* @param victim The callback to remove
*
* @throws IllegalStateException If {@link #isAlive()} returns false
*
* @see #addOnComputeInternalInsetsListener(OnComputeInternalInsetsListener)
*
* We are not yet ready to commit to this API and support it, so
* @hide
*/
public void removeOnComputeInternalInsetsListener(OnComputeInternalInsetsListener victim) {
checkIsAlive();
if (mOnComputeInternalInsetsListeners == null) {
return;
}
mOnComputeInternalInsetsListeners.remove(victim);
}
private void checkIsAlive() {
if (!mAlive) {
throw new IllegalStateException("This ViewTreeObserver is not alive, call "
+ "getViewTreeObserver() again");
}
}
/**
* Indicates whether this ViewTreeObserver is alive. When an observer is not alive,
* any call to a method (except this one) will throw an exception.
*
* If an application keeps a long-lived reference to this ViewTreeObserver, it should
* always check for the result of this method before calling any other method.
*
* @return True if this object is alive and be used, false otherwise.
*/
public boolean isAlive() {
return mAlive;
}
/**
* Marks this ViewTreeObserver as not alive. After invoking this method, invoking
* any other method but {@link #isAlive()} and {@link #kill()} will throw an Exception.
*
* @hide
*/
private void kill() {
mAlive = false;
}
/**
* Notifies registered listeners that focus has changed.
*/
final void dispatchOnGlobalFocusChange(View oldFocus, View newFocus) {
// NOTE: because of the use of CopyOnWriteArrayList, we *must* use an iterator to
// perform the dispatching. The iterator is a safe guard against listeners that
// could mutate the list by calling the various add/remove methods. This prevents
// the array from being modified while we iterate it.
final CopyOnWriteArrayList<OnGlobalFocusChangeListener> listeners = mOnGlobalFocusListeners;
if (listeners != null) {
for (OnGlobalFocusChangeListener listener : listeners) {
listener.onGlobalFocusChanged(oldFocus, newFocus);
}
}
}
/**
* Notifies registered listeners that a global layout happened. This can be called
* manually if you are forcing a layout on a View or a hierarchy of Views that are
* not attached to a Window or in the GONE state.
*/
public final void dispatchOnGlobalLayout() {
// NOTE: because of the use of CopyOnWriteArrayList, we *must* use an iterator to
// perform the dispatching. The iterator is a safe guard against listeners that
// could mutate the list by calling the various add/remove methods. This prevents
// the array from being modified while we iterate it.
final CopyOnWriteArrayList<OnGlobalLayoutListener> listeners = mOnGlobalLayoutListeners;
if (listeners != null) {
for (OnGlobalLayoutListener listener : listeners) {
listener.onGlobalLayout();
}
}
}
/**
* Notifies registered listeners that the drawing pass is about to start. If a
* listener returns true, then the drawing pass is canceled and rescheduled. This can
* be called manually if you are forcing the drawing on a View or a hierarchy of Views
* that are not attached to a Window or in the GONE state.
*
* @return True if the current draw should be canceled and resceduled, false otherwise.
*/
public final boolean dispatchOnPreDraw() {
// NOTE: because of the use of CopyOnWriteArrayList, we *must* use an iterator to
// perform the dispatching. The iterator is a safe guard against listeners that
// could mutate the list by calling the various add/remove methods. This prevents
// the array from being modified while we iterate it.
boolean cancelDraw = false;
final CopyOnWriteArrayList<OnPreDrawListener> listeners = mOnPreDrawListeners;
if (listeners != null) {
for (OnPreDrawListener listener : listeners) {
cancelDraw |= !listener.onPreDraw();
}
}
return cancelDraw;
}
/**
* Notifies registered listeners that the touch mode has changed.
*
* @param inTouchMode True if the touch mode is now enabled, false otherwise.
*/
final void dispatchOnTouchModeChanged(boolean inTouchMode) {
// NOTE: because of the use of CopyOnWriteArrayList, we *must* use an iterator to
// perform the dispatching. The iterator is a safe guard against listeners that
// could mutate the list by calling the various add/remove methods. This prevents
// the array from being modified while we iterate it.
final CopyOnWriteArrayList<OnTouchModeChangeListener> listeners =
mOnTouchModeChangeListeners;
if (listeners != null) {
for (OnTouchModeChangeListener listener : listeners) {
listener.onTouchModeChanged(inTouchMode);
}
}
}
/**
* Notifies registered listeners that something has scrolled.
*/
final void dispatchOnScrollChanged() {
// NOTE: because of the use of CopyOnWriteArrayList, we *must* use an iterator to
// perform the dispatching. The iterator is a safe guard against listeners that
// could mutate the list by calling the various add/remove methods. This prevents
// the array from being modified while we iterate it.
final CopyOnWriteArrayList<OnScrollChangedListener> listeners = mOnScrollChangedListeners;
if (listeners != null) {
for (OnScrollChangedListener listener : listeners) {
listener.onScrollChanged();
}
}
}
/**
* Returns whether there are listeners for computing internal insets.
*/
final boolean hasComputeInternalInsetsListeners() {
final CopyOnWriteArrayList<OnComputeInternalInsetsListener> listeners =
mOnComputeInternalInsetsListeners;
return (listeners != null && listeners.size() > 0);
}
/**
* Calls all listeners to compute the current insets.
*/
final void dispatchOnComputeInternalInsets(InternalInsetsInfo inoutInfo) {
// NOTE: because of the use of CopyOnWriteArrayList, we *must* use an iterator to
// perform the dispatching. The iterator is a safe guard against listeners that
// could mutate the list by calling the various add/remove methods. This prevents
// the array from being modified while we iterate it.
final CopyOnWriteArrayList<OnComputeInternalInsetsListener> listeners =
mOnComputeInternalInsetsListeners;
if (listeners != null) {
for (OnComputeInternalInsetsListener listener : listeners) {
listener.onComputeInternalInsets(inoutInfo);
}
}
}
}
|
