下面列出了android.view.ViewTreeObserver#isAlive ( ) 实例代码，或者点击链接到github查看源代码，也可以在右侧发表评论。
/**
* Removes global layout listener added in {@link #addGlobalLayoutListener()}.
*/
void removeGlobalLayoutListener()
{
final ViewGroup parent = (ViewGroup) mView.getParent();
if (parent == null)
{
return;
}
final ViewTreeObserver viewTreeObserver = ((ViewGroup) mView.getParent()).getViewTreeObserver();
if (viewTreeObserver.isAlive())
{
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)
{
viewTreeObserver.removeOnGlobalLayoutListener(mGlobalLayoutListener);
}
else
{
viewTreeObserver.removeGlobalOnLayoutListener(mGlobalLayoutListener);
}
}
}
private void checkCurrentDimens() {
if (cbs.isEmpty()) {
return;
}
int currentWidth = getViewWidthOrParam();
int currentHeight = getViewHeightOrParam();
if (!isSizeValid(currentWidth) || !isSizeValid(currentHeight)) {
return;
}
notifyCbs(currentWidth, currentHeight);
// Keep a reference to the layout listener and remove it here
// rather than having the observer remove itself because the observer
// we add the listener to will be almost immediately merged into
// another observer and will therefore never be alive. If we instead
// keep a reference to the listener and remove it here, we get the
// current view tree observer and should succeed.
ViewTreeObserver observer = view.getViewTreeObserver();
if (observer.isAlive()) {
observer.removeOnPreDrawListener(layoutListener);
}
layoutListener = null;
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
ActivityChooserModel dataModel = mAdapter.getDataModel();
if (dataModel != null) {
try {
dataModel.unregisterObserver(mModelDataSetOberver);
} catch (IllegalStateException e) {
//Oh, well... fixes issue #557
}
}
ViewTreeObserver viewTreeObserver = getViewTreeObserver();
if (viewTreeObserver.isAlive()) {
viewTreeObserver.removeGlobalOnLayoutListener(mOnGlobalLayoutListener);
}
mIsAttachedToWindow = false;
}
private void scrollToTabAfterLayout(final int tabIndex) {
//from http://stackoverflow.com/a/34780589/3697225
if (tabs != null) {
final ViewTreeObserver observer = tabs.getViewTreeObserver();
if (observer.isAlive()) {
observer.dispatchOnGlobalLayout(); // In case a previous call is waiting when this call is made
observer.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
tabs.getViewTreeObserver().removeGlobalOnLayoutListener(this);
tabs.getTabAt(tabIndex).select();
}
});
}
}
}
private void scrollToTabAfterLayout(final int tabIndex) {
//from http://stackoverflow.com/a/34780589/3697225
if (mTabLayout != null) {
final ViewTreeObserver observer = mTabLayout.getViewTreeObserver();
if (observer.isAlive()) {
observer.dispatchOnGlobalLayout(); // In case a previous call is waiting when this call is made
observer.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
mTabLayout.getViewTreeObserver().removeGlobalOnLayoutListener(this);
mTabLayout.getTabAt(tabIndex).select();
}
});
}
}
}
void mount(
ComponentTree contentComponentTree,
final ScrollPosition scrollPosition,
boolean isIncrementalMountEnabled) {
mLithoView.setComponentTree(contentComponentTree);
mIsIncrementalMountEnabled = isIncrementalMountEnabled;
mScrollPosition = scrollPosition;
final ViewTreeObserver.OnPreDrawListener onPreDrawListener =
new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
setScrollY(scrollPosition.y);
ViewTreeObserver currentViewTreeObserver = getViewTreeObserver();
if (currentViewTreeObserver.isAlive()) {
currentViewTreeObserver.removeOnPreDrawListener(this);
}
return true;
}
};
getViewTreeObserver().addOnPreDrawListener(onPreDrawListener);
mOnPreDrawListener = onPreDrawListener;
}
/**
* Toggles the material floating action button.
*
* @param visible
*/
public void toggleButton(final boolean visible) {
if (isFabShowing != visible) {
isFabShowing = visible;
int height = fab.getHeight();
if (height == 0) {
ViewTreeObserver vto = fab.getViewTreeObserver();
if (vto.isAlive()) {
vto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
ViewTreeObserver currentVto = fab.getViewTreeObserver();
if (currentVto.isAlive()) {
currentVto.removeOnPreDrawListener(this);
}
toggleButton(visible);
return true;
}
});
return;
}
}
int translationY = visible ? 0 : height;
fab.animate().setInterpolator(interpolator)
.setDuration(350)
.translationY(translationY);
// On pre-Honeycomb a translated view is still clickable, so we need to disable clicks manually
fab.setClickable(visible);
}
}
/**
* Clean-up the resources attached to this object. This needs to be called when the ImageView is
* no longer used. A good example is from {@link android.view.View#onDetachedFromWindow()} or
* from {@link android.app.Activity#onDestroy()}. This is automatically called if you are using
* {@link uk.co.senab.photoview.PhotoView}.
*/
@SuppressWarnings("deprecation")
public void cleanup() {
if (null == mImageView) {
return; // cleanup already done
}
final ImageView imageView = mImageView.get();
if (null != imageView) {
// Remove this as a global layout listener
ViewTreeObserver observer = imageView.getViewTreeObserver();
if (null != observer && observer.isAlive()) {
observer.removeGlobalOnLayoutListener(this);
}
// Remove the ImageView's reference to this
imageView.setOnTouchListener(null);
// make sure a pending fling runnable won't be run
cancelFling();
}
if (null != mGestureDetector) {
mGestureDetector.setOnDoubleTapListener(null);
}
// Clear listeners too
mMatrixChangeListener = null;
mPhotoTapListener = null;
mViewTapListener = null;
// Finally, clear ImageView
mImageView = null;
}
static void removeGlobalLayoutListener(View view, ViewTreeObserver.OnGlobalLayoutListener onGlobalLayoutListener) {
final ViewTreeObserver observer = view.getViewTreeObserver();
if (!observer.isAlive()) {
return;
}
if (Build.VERSION.SDK_INT >= 16) {
observer.removeOnGlobalLayoutListener(onGlobalLayoutListener);
} else {
//noinspection deprecation
observer.removeGlobalOnLayoutListener(onGlobalLayoutListener);
}
}
/**
* Adds layout listener to view parent to capture layout changes.
*/
void addGlobalLayoutListener()
{
final ViewTreeObserver viewTreeObserver = ((ViewGroup) mView.getParent()).getViewTreeObserver();
if (viewTreeObserver.isAlive())
{
viewTreeObserver.addOnGlobalLayoutListener(mGlobalLayoutListener);
}
}
/**
* Clean-up the resources attached to this object. This needs to be called when the ImageView is
* no longer used. A good example is from {@link android.view.View#onDetachedFromWindow()} or
* from {@link android.app.Activity#onDestroy()}. This is automatically called if you are using
* {@link uk.co.senab.photoview.PhotoView}.
*/
@SuppressWarnings("deprecation")
public void cleanup() {
if (null == mImageView) {
return; // cleanup already done
}
final ImageView imageView = mImageView.get();
if (null != imageView) {
// Remove this as a global layout listener
ViewTreeObserver observer = imageView.getViewTreeObserver();
if (null != observer && observer.isAlive()) {
observer.removeGlobalOnLayoutListener(this);
}
// Remove the ImageView's reference to this
imageView.setOnTouchListener(null);
// make sure a pending fling runnable won't be run
cancelFling();
}
if (null != mGestureDetector) {
mGestureDetector.setOnDoubleTapListener(null);
}
// Clear listeners too
mMatrixChangeListener = null;
mPhotoTapListener = null;
mViewTapListener = null;
// Finally, clear ImageView
mImageView = null;
}
private void toggle(final boolean visible, final boolean animate, boolean force) {
if (mVisible != visible || force) {
mVisible = visible;
int height = floatActionButton.getHeight();
if (height == 0 && !force) {
ViewTreeObserver vto = floatActionButton.getViewTreeObserver();
if (vto.isAlive()) {
vto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
ViewTreeObserver currentVto = floatActionButton.getViewTreeObserver();
if (currentVto.isAlive()) {
currentVto.removeOnPreDrawListener(this);
}
toggle(visible, animate, true);
return true;
}
});
return;
}
}
int translationY = visible ? 0 : height + getMarginBottom();
if (animate) {
ViewPropertyAnimator.animate(floatActionButton).setInterpolator(mInterpolator)
.setDuration(TRANSLATE_DURATION_MILLIS)
.translationY(translationY);
} else {
ViewHelper.setTranslationY(floatActionButton, translationY);
}
}
}
private void toggle(final boolean visible, final boolean animate, boolean force) {
if (mVisible != visible || force) {
mVisible = visible;
int height = getHeight();
if (height == 0 && !force) {
ViewTreeObserver vto = getViewTreeObserver();
if (vto.isAlive()) {
vto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
ViewTreeObserver currentVto = getViewTreeObserver();
if (currentVto.isAlive()) {
currentVto.removeOnPreDrawListener(this);
}
toggle(visible, animate, true);
return true;
}
});
return;
}
}
int translationY = visible ? 0 : height + mAddButton.getMarginBottom();
if (animate) {
ViewPropertyAnimator.animate(this).setInterpolator(mInterpolator)
.setDuration(TRANSLATE_DURATION_MILLIS)
.translationY(translationY);
} else {
ViewHelper.setTranslationY(this, translationY);
}
// On pre-Honeycomb a translated view is still clickable, so we need to disable clicks manually
if (!hasHoneycombApi()) {
setClickable(visible);
}
}
}
/**
* Clean-up the resources attached to this object. This needs to be called when the ImageView is
* no longer used. A good example is from {@link android.view.View#onDetachedFromWindow()} or
* from {@link android.app.Activity#onDestroy()}. This is automatically called if you are using
* {@link uk.co.senab.photoview.PhotoView}.
*/
@SuppressWarnings("deprecation")
public void cleanup() {
if (null == mImageView) {
return; // cleanup already done
}
final ImageView imageView = mImageView.get();
if (null != imageView) {
// Remove this as a global layout listener
ViewTreeObserver observer = imageView.getViewTreeObserver();
if (null != observer && observer.isAlive()) {
observer.removeGlobalOnLayoutListener(this);
}
// Remove the ImageView's reference to this
imageView.setOnTouchListener(null);
// make sure a pending fling runnable won't be run
cancelFling();
}
if (null != mGestureDetector) {
mGestureDetector.setOnDoubleTapListener(null);
}
// Clear listeners too
mMatrixChangeListener = null;
mPhotoTapListener = null;
mViewTapListener = null;
// Finally, clear ImageView
mImageView = null;
}
/**
* Clean-up the resources attached to this object. This needs to be called
* when the ImageView is no longer used. A good example is from
* {@link android.view.View#onDetachedFromWindow()} or from
* {@link android.app.Activity#onDestroy()}. This is automatically called if
* you are using {@link com.antonioleiva.materialeverywhere.uk.co.senab.photoview.PhotoView}.
*/
@SuppressWarnings("deprecation")
public final void cleanup() {
if (null == mImageView) {
return; // cleanup already done
}
final ImageView imageView = mImageView.get();
if (null != imageView) {
// Remove this as a global layout listener
ViewTreeObserver observer = imageView.getViewTreeObserver();
if (null != observer && observer.isAlive()) {
observer.removeGlobalOnLayoutListener(this);
}
// Remove the ImageView's reference to this
imageView.setOnTouchListener(null);
// make sure a pending fling runnable won't be run
cancelFling();
}
if (null != mGestureDetector) {
mGestureDetector.setOnDoubleTapListener(null);
}
// Clear listeners too
mMatrixChangeListener = null;
mPhotoTapListener = null;
mViewTapListener = null;
// Finally, clear ImageView
mImageView = null;
}
/**
* Toggles the material floating action button.
*
* @param visible
*/
public void toggleButton(final boolean visible) {
if (isFabShowing != visible) {
isFabShowing = visible;
int height = fab.getHeight();
if (height == 0) {
ViewTreeObserver vto = fab.getViewTreeObserver();
if (vto.isAlive()) {
vto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
ViewTreeObserver currentVto = fab.getViewTreeObserver();
if (currentVto.isAlive()) {
currentVto.removeOnPreDrawListener(this);
}
toggleButton(visible);
return true;
}
});
return;
}
}
int translationY = visible ? 0 : height;
fab.animate().setInterpolator(interpolator)
.setDuration(350)
.translationY(translationY);
// On pre-Honeycomb a translated view is still clickable, so we need to disable clicks manually
fab.setClickable(visible);
}
}
private void toggle(final boolean visible, final boolean animate, boolean force) {
if (mVisible != visible || force) {
mVisible = visible;
int height = getHeight();
if (height == 0 && !force) {
ViewTreeObserver vto = getViewTreeObserver();
if (vto.isAlive()) {
vto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
ViewTreeObserver currentVto = getViewTreeObserver();
if (currentVto.isAlive()) {
currentVto.removeOnPreDrawListener(this);
}
toggle(visible, animate, true);
return true;
}
});
return;
}
}
int translationY = visible ? 0 : height + getMarginBottom();
if (animate) {
animate().setInterpolator(mInterpolator)
.setDuration(TRANSLATE_DURATION_MILLIS)
.translationY(translationY);
} else {
setTranslationY(translationY);
}
// On pre-Honeycomb a translated view is still clickable, so we need to disable clicks manually
if (!Utils.hasHoneycomb()) {
setClickable(visible);
}
}
}
/**
* Clean-up the resources attached to this object. This needs to be called when the ImageView is
* no longer used. A good example is from {@link View#onDetachedFromWindow()} or
* from {@link android.app.Activity#onDestroy()}. This is automatically called if you are using
* {@link PhotoView}.
*/
@SuppressWarnings("deprecation")
public void cleanup() {
if (null == mImageView) {
return; // cleanup already done
}
final ImageView imageView = mImageView.get();
if (null != imageView) {
// Remove this as a global layout listener
ViewTreeObserver observer = imageView.getViewTreeObserver();
if (null != observer && observer.isAlive()) {
observer.removeGlobalOnLayoutListener(this);
}
// Remove the ImageView's reference to this
imageView.setOnTouchListener(null);
// make sure a pending fling runnable won't be run
cancelFling();
}
if (null != mGestureDetector) {
mGestureDetector.setOnDoubleTapListener(null);
}
// Clear listeners too
mMatrixChangeListener = null;
mPhotoTapListener = null;
mViewTapListener = null;
// Finally, clear ImageView
mImageView = null;
}
private void toggle(final boolean visible, final boolean animate, boolean force) {
if (mVisible != visible || force) {
mVisible = visible;
int height = getHeight();
if (height == 0 && !force) {
ViewTreeObserver vto = getViewTreeObserver();
if (vto.isAlive()) {
vto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
ViewTreeObserver currentVto = getViewTreeObserver();
if (currentVto.isAlive()) {
currentVto.removeOnPreDrawListener(this);
}
toggle(visible, animate, true);
return true;
}
});
return;
}
}
int translationY = visible ? 0 : height + getMarginBottom();
if (animate) {
animate().setInterpolator(mInterpolator)
.setDuration(TRANSLATE_DURATION_MILLIS)
.translationY(translationY);
} else {
setTranslationY(translationY);
}
// On pre-Honeycomb a translated view is still clickable, so we need to disable clicks manually
if (!Utils.hasHoneycomb()) {
setClickable(visible);
}
}
if(isMenuOpen()) {
closeMenu();
}
}
private void waitForNextFrame() {
ViewTreeObserver treeObserver = getViewTreeObserver();
if (treeObserver != null && treeObserver.isAlive()) {
treeObserver.addOnPreDrawListener(new PreDrawListener());
}
}