Switched Task to use WindowContainer (f6192868) · Commits · e / os / android_frameworks_base

services/core/java/com/android/server/wm/AppWindowToken.java

+3 −1

Original line number	Diff line number	Diff line
		@@ -76,6 +76,7 @@ class AppWindowToken extends WindowToken implements WindowManagerService.AppFree

		final boolean voiceInteraction;

		// TODO: Use getParent instead?
		Task mTask;
		/** @see WindowContainer#fillsParent() */
		private boolean mFillsParent;
		@@ -373,7 +374,8 @@ class AppWindowToken extends WindowToken implements WindowManagerService.AppFree
		mIsExiting = false;
		removeAllWindows();
		if (mTask != null) {
		mTask.detachChild(this);
		mTask.mStack.mExitingAppTokens.remove(this);
		mTask.removeChild(this);
		}
		}

services/core/java/com/android/server/wm/DisplayContent.java

+1 −1

Original line number	Diff line number	Diff line
		@@ -371,7 +371,7 @@ class DisplayContent {
		mStacks.add(addIndex, stack);
		}

		// TODO: Don't forget to switch to WC.detachChild
		// TODO: Don't forget to switch to WC.removeChild
		void detachChild(TaskStack stack) {
		detachStack(stack);
		if (stack.detachFromDisplay()) {

services/core/java/com/android/server/wm/Task.java

+58 −227

Original line number	Diff line number	Diff line
		@@ -21,9 +21,6 @@ import static android.app.ActivityManager.StackId.PINNED_STACK_ID;
		import static android.app.ActivityManager.StackId.FREEFORM_WORKSPACE_STACK_ID;
		import static android.app.ActivityManager.StackId.HOME_STACK_ID;
		import static android.content.pm.ActivityInfo.RESIZE_MODE_CROP_WINDOWS;
		import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_BEHIND;
		import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_UNSET;
		import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED;
		import static com.android.server.wm.WindowManagerDebugConfig.DEBUG_STACK;
		import static com.android.server.wm.WindowManagerDebugConfig.TAG_WITH_CLASS_NAME;
		import static com.android.server.wm.WindowManagerDebugConfig.TAG_WM;
		@@ -37,14 +34,13 @@ import android.util.EventLog;
		import android.util.Slog;
		import android.view.DisplayInfo;
		import android.view.Surface;
		import android.view.animation.Animation;

		import android.view.SurfaceControl;
		import com.android.server.EventLogTags;

		import java.io.PrintWriter;

		class Task implements DimLayer.DimLayerUser {
		class Task extends WindowContainer<AppWindowToken> implements DimLayer.DimLayerUser {
		static final String TAG = TAG_WITH_CLASS_NAME ? "Task" : TAG_WM;
		// Return value from {@link setBounds} indicating no change was made to the Task bounds.
		static final int BOUNDS_CHANGE_NONE = 0;
		@@ -53,8 +49,8 @@ class Task implements DimLayer.DimLayerUser {
		// Return value from {@link setBounds} indicating the size of the Task bounds changed.
		static final int BOUNDS_CHANGE_SIZE = 1 << 1;

		// TODO: Track parent marks like this in WindowContainer.
		TaskStack mStack;
		private final AppTokenList mAppTokens = new AppTokenList();
		final int mTaskId;
		final int mUserId;
		boolean mDeferRemoval = false;
		@@ -112,18 +108,22 @@ class Task implements DimLayer.DimLayerUser {
		}

		void addAppToken(int addPos, AppWindowToken wtoken, int resizeMode, boolean homeTask) {
		final int lastPos = mAppTokens.size();
		final int lastPos = mChildren.size();
		if (addPos >= lastPos) {
		addPos = lastPos;
		} else {
		for (int pos = 0; pos < lastPos && pos < addPos; ++pos) {
		if (mAppTokens.get(pos).removed) {
		if (mChildren.get(pos).removed) {
		// addPos assumes removed tokens are actually gone.
		++addPos;
		}
		}
		}
		mAppTokens.add(addPos, wtoken);

		if (wtoken.mParent != null) {
		wtoken.mParent.removeChild(wtoken);
		}
		addChild(wtoken, addPos);
		wtoken.mTask = this;
		mDeferRemoval = false;
		mResizeMode = resizeMode;
		@@ -131,15 +131,16 @@ class Task implements DimLayer.DimLayerUser {
		}

		private boolean hasWindowsAlive() {
		for (int i = mAppTokens.size() - 1; i >= 0; i--) {
		if (mAppTokens.get(i).hasWindowsAlive()) {
		for (int i = mChildren.size() - 1; i >= 0; i--) {
		if (mChildren.get(i).hasWindowsAlive()) {
		return true;
		}
		}
		return false;
		}

		void removeLocked() {
		@Override
		void removeIfPossible() {
		if (hasWindowsAlive() && mStack.isAnimating()) {
		if (DEBUG_STACK) Slog.i(TAG, "removeTask: deferring removing taskId=" + mTaskId);
		mDeferRemoval = true;
		@@ -156,6 +157,7 @@ class Task implements DimLayer.DimLayerUser {
		mService.mTaskIdToTask.delete(mTaskId);
		}

		// Change to use reparenting in WC when TaskStack is switched to use WC.
		void moveTaskToStack(TaskStack stack, boolean toTop) {
		if (stack == mStack) {
		return;
		@@ -179,48 +181,31 @@ class Task implements DimLayer.DimLayerUser {
		stack.positionTask(this, position, showForAllUsers());
		resizeLocked(bounds, config, false /* force */);

		for (int activityNdx = mAppTokens.size() - 1; activityNdx >= 0; --activityNdx) {
		mAppTokens.get(activityNdx).notifyMovedInStack();
		for (int activityNdx = mChildren.size() - 1; activityNdx >= 0; --activityNdx) {
		mChildren.get(activityNdx).notifyMovedInStack();
		}
		}

		boolean checkCompleteDeferredRemoval() {
		boolean stillDeferringRemoval = false;

		for (int tokenNdx = mAppTokens.size() - 1; tokenNdx >= 0; --tokenNdx) {
		final AppWindowToken token = mAppTokens.get(tokenNdx);
		stillDeferringRemoval \|= token.checkCompleteDeferredRemoval();
		}

		return stillDeferringRemoval;
		void removeChild(AppWindowToken token) {
		if (!mChildren.contains(token)) {
		Slog.e(TAG, "removeChild: token=" + this + " not found.");
		return;
		}

		// TODO: Don't forget to switch to WC.detachChild
		void detachChild(AppWindowToken wtoken) {
		if (!removeAppToken(wtoken)) {
		Slog.e(TAG, "detachChild: token=" + this + " not found.");
		}
		mStack.mExitingAppTokens.remove(wtoken);
		}
		super.removeChild(token);

		boolean removeAppToken(AppWindowToken wtoken) {
		boolean removed = mAppTokens.remove(wtoken);
		if (mAppTokens.size() == 0) {
		if (mChildren.isEmpty()) {
		EventLog.writeEvent(EventLogTags.WM_TASK_REMOVED, mTaskId, "removeAppToken: last token");
		if (mDeferRemoval) {
		removeLocked();
		removeIfPossible();
		}
		}
		wtoken.mTask = null;
		/* Leave mTaskId for now, it might be useful for debug
		wtoken.mTaskId = -1;
		*/
		return removed;
		token.mTask = null;
		}

		void setSendingToBottom(boolean toBottom) {
		for (int appTokenNdx = 0; appTokenNdx < mAppTokens.size(); appTokenNdx++) {
		mAppTokens.get(appTokenNdx).sendingToBottom = toBottom;
		for (int appTokenNdx = 0; appTokenNdx < mChildren.size(); appTokenNdx++) {
		mChildren.get(appTokenNdx).sendingToBottom = toBottom;
		}
		}

		@@ -370,13 +355,10 @@ class Task implements DimLayer.DimLayerUser {
		/** Return true if the current bound can get outputted to the rest of the system as-is. */
		private boolean useCurrentBounds() {
		final DisplayContent displayContent = mStack.getDisplayContent();
		if (mFullscreen
		return mFullscreen
		\|\| !StackId.isTaskResizeableByDockedStack(mStack.mStackId)
		\|\| displayContent == null
		\|\| displayContent.getDockedStackVisibleForUserLocked() != null) {
		return true;
		}
		return false;
		\|\| displayContent.getDockedStackVisibleForUserLocked() != null;
		}

		/** Original bounds of the task if applicable, otherwise fullscreen rect. */
		@@ -407,8 +389,8 @@ class Task implements DimLayer.DimLayerUser {
		*/
		boolean getMaxVisibleBounds(Rect out) {
		boolean foundTop = false;
		for (int i = mAppTokens.size() - 1; i >= 0; i--) {
		final AppWindowToken token = mAppTokens.get(i);
		for (int i = mChildren.size() - 1; i >= 0; i--) {
		final AppWindowToken token = mChildren.get(i);
		// skip hidden (or about to hide) apps
		if (token.mIsExiting \|\| token.clientHidden \|\| token.hiddenRequested) {
		continue;
		@@ -444,8 +426,8 @@ class Task implements DimLayer.DimLayerUser {
		final DisplayContent displayContent = mStack.getDisplayContent();
		// It doesn't matter if we in particular are part of the resize, since we couldn't have
		// a DimLayer anyway if we weren't visible.
		final boolean dockedResizing = displayContent != null ?
		displayContent.mDividerControllerLocked.isResizing() : false;
		final boolean dockedResizing = displayContent != null
		&& displayContent.mDividerControllerLocked.isResizing();
		if (useCurrentBounds()) {
		if (inFreeformWorkspace() && getMaxVisibleBounds(out)) {
		return;
		@@ -471,11 +453,12 @@ class Task implements DimLayer.DimLayerUser {
		return;
		}

		// The bounds has been adjusted to accommodate for a docked stack, but the docked stack
		// is not currently visible. Go ahead a represent it as fullscreen to the rest of the
		// system.
		// The bounds has been adjusted to accommodate for a docked stack, but the docked stack is
		// not currently visible. Go ahead a represent it as fullscreen to the rest of the system.
		if (displayContent != null) {
		displayContent.getLogicalDisplayRect(out);
		}
		}

		void setDragResizing(boolean dragResizing, int dragResizeMode) {
		if (mDragResizing != dragResizing) {
		@@ -489,12 +472,6 @@ class Task implements DimLayer.DimLayerUser {
		}
		}

		private void resetDragResizingChangeReported() {
		for (int activityNdx = mAppTokens.size() - 1; activityNdx >= 0; --activityNdx) {
		mAppTokens.get(activityNdx).resetDragResizingChangeReported();
		}
		}

		boolean isDragResizing() {
		return mDragResizing;
		}
		@@ -503,24 +480,6 @@ class Task implements DimLayer.DimLayerUser {
		return mDragResizeMode;
		}

		/**
		* Adds all of the tasks windows to {@link WindowManagerService#mWaitingForDrawn} if drag
		* resizing state of the window has been changed.
		*/
		void setWaitingForDrawnIfResizingChanged() {
		for (int i = mAppTokens.size() - 1; i >= 0; --i) {
		mAppTokens.get(i).setWaitingForDrawnIfResizingChanged();
		}
		}

		boolean detachFromDisplay() {
		boolean didSomething = false;
		for (int i = mAppTokens.size() - 1; i >= 0; --i) {
		didSomething \|= mAppTokens.get(i).detachFromDisplay();
		}
		return didSomething;
		}

		void updateDisplayInfo(final DisplayContent displayContent) {
		if (displayContent == null) {
		return;
		@@ -556,59 +515,23 @@ class Task implements DimLayer.DimLayerUser {
		}
		}

		private void onResize() {
		for (int activityNdx = mAppTokens.size() - 1; activityNdx >= 0; --activityNdx) {
		mAppTokens.get(activityNdx).onResize();
		}
		}

		private void onMovedByResize() {
		for (int i = mAppTokens.size() - 1; i >= 0; --i) {
		mAppTokens.get(i).onMovedByResize();
		}
		}

		/**
		* Cancels any running app transitions associated with the task.
		*/
		/** Cancels any running app transitions associated with the task. */
		void cancelTaskWindowTransition() {
		for (int activityNdx = mAppTokens.size() - 1; activityNdx >= 0; --activityNdx) {
		mAppTokens.get(activityNdx).mAppAnimator.clearAnimation();
		for (int i = mChildren.size() - 1; i >= 0; --i) {
		mChildren.get(i).mAppAnimator.clearAnimation();
		}
		}

		/**
		* Cancels any running thumbnail transitions associated with the task.
		*/
		/** Cancels any running thumbnail transitions associated with the task. */
		void cancelTaskThumbnailTransition() {
		for (int activityNdx = mAppTokens.size() - 1; activityNdx >= 0; --activityNdx) {
		mAppTokens.get(activityNdx).mAppAnimator.clearThumbnail();
		for (int i = mChildren.size() - 1; i >= 0; --i) {
		mChildren.get(i).mAppAnimator.clearThumbnail();
		}
		}

		boolean showForAllUsers() {
		final int tokensCount = mAppTokens.size();
		return (tokensCount != 0) && mAppTokens.get(tokensCount - 1).showForAllUsers;
		}

		boolean hasContentToDisplay() {
		for (int i = mAppTokens.size() - 1; i >= 0; i--) {
		final AppWindowToken appToken = mAppTokens.get(i);
		if (appToken.hasContentToDisplay()) {
		return true;
		}
		}
		return false;
		}

		boolean isVisible() {
		for (int i = mAppTokens.size() - 1; i >= 0; i--) {
		final AppWindowToken appToken = mAppTokens.get(i);
		if (appToken.isVisible()) {
		return true;
		}
		}
		return false;
		final int tokensCount = mChildren.size();
		return (tokensCount != 0) && mChildren.get(tokensCount - 1).showForAllUsers;
		}

		boolean inHomeStack() {
		@@ -633,8 +556,8 @@ class Task implements DimLayer.DimLayerUser {
		}

		AppWindowToken getTopVisibleAppToken() {
		for (int i = mAppTokens.size() - 1; i >= 0; i--) {
		final AppWindowToken token = mAppTokens.get(i);
		for (int i = mChildren.size() - 1; i >= 0; i--) {
		final AppWindowToken token = mChildren.get(i);
		// skip hidden (or about to hide) apps
		if (!token.mIsExiting && !token.clientHidden && !token.hiddenRequested) {
		return token;
		@@ -663,82 +586,21 @@ class Task implements DimLayer.DimLayerUser {
		return mStack.getDisplayContent().getDisplayInfo();
		}

		/**
		* See {@link WindowManagerService#overridePlayingAppAnimationsLw}
		*/
		void overridePlayingAppAnimations(Animation a) {
		for (int i = mAppTokens.size() - 1; i >= 0; i--) {
		mAppTokens.get(i).overridePlayingAppAnimations(a);
		}
		}

		void forceWindowsScaleable(boolean force) {
		SurfaceControl.openTransaction();
		try {
		for (int i = mAppTokens.size() - 1; i >= 0; i--) {
		mAppTokens.get(i).forceWindowsScaleableInTransaction(force);
		for (int i = mChildren.size() - 1; i >= 0; i--) {
		mChildren.get(i).forceWindowsScaleableInTransaction(force);
		}
		} finally {
		SurfaceControl.closeTransaction();
		}
		}

		boolean isAnimating() {
		for (int i = mAppTokens.size() - 1; i >= 0; i--) {
		final AppWindowToken aToken = mAppTokens.get(i);
		if (aToken.isAnimating()) {
		return true;
		}
		}
		return false;
		}

		void checkAppWindowsReadyToShow(int displayId) {
		for (int i = mAppTokens.size() - 1; i >= 0; --i) {
		final AppWindowToken aToken = mAppTokens.get(i);
		aToken.checkAppWindowsReadyToShow(displayId);
		}
		}

		void updateAllDrawn(int displayId) {
		for (int i = mAppTokens.size() - 1; i >= 0; --i) {
		final AppWindowToken aToken = mAppTokens.get(i);
		aToken.updateAllDrawn(displayId);
		}
		}

		void stepAppWindowsAnimation(long currentTime, int displayId) {
		for (int i = mAppTokens.size() - 1; i >= 0; --i) {
		final AppWindowToken aToken = mAppTokens.get(i);
		aToken.stepAppWindowsAnimation(currentTime, displayId);
		}
		}

		void onAppTransitionDone() {
		for (int i = mAppTokens.size() - 1; i >= 0; --i) {
		final AppWindowToken token = mAppTokens.get(i);
		token.onAppTransitionDone();
		}
		}

		// TODO: Use WindowContainer.compareTo() once everything is using WindowContainer
		boolean isFirstGreaterThanSecond(AppWindowToken first, AppWindowToken second) {
		return mAppTokens.indexOf(first) > mAppTokens.indexOf(second);
		}

		int rebuildWindowList(DisplayContent dc, int addIndex) {
		final int count = mAppTokens.size();
		for (int i = 0; i < count; i++) {
		final AppWindowToken token = mAppTokens.get(i);
		addIndex = token.rebuildWindowList(dc, addIndex);
		}
		return addIndex;
		}

		void getWindowOnDisplayBeforeToken(DisplayContent dc, WindowToken token,
		DisplayContent.GetWindowOnDisplaySearchResult result) {
		for (int i = mAppTokens.size() - 1; i >= 0; --i) {
		final AppWindowToken current = mAppTokens.get(i);
		for (int i = mChildren.size() - 1; i >= 0; --i) {
		final AppWindowToken current = mChildren.get(i);
		if (current == token) {
		// We have reach the token we are interested in. End search.
		result.reachedToken = true;
		@@ -756,8 +618,8 @@ class Task implements DimLayer.DimLayerUser {

		void getWindowOnDisplayAfterToken(DisplayContent dc, WindowToken token,
		DisplayContent.GetWindowOnDisplaySearchResult result) {
		for (int i = mAppTokens.size() - 1; i >= 0; --i) {
		final AppWindowToken current = mAppTokens.get(i);
		for (int i = mChildren.size() - 1; i >= 0; --i) {
		final AppWindowToken current = mChildren.get(i);
		if (!result.reachedToken) {
		if (current == token) {
		// We have reached the token we are interested in. Get whichever window occurs
		@@ -775,36 +637,14 @@ class Task implements DimLayer.DimLayerUser {
		}
		}

		@Override
		boolean fillsParent() {
		return mFullscreen \|\| !StackId.isTaskResizeAllowed(mStack.mStackId);
		}

		// TODO: Remove once switched to use WindowContainer
		int getOrientation() {
		int candidate = SCREEN_ORIENTATION_UNSET;

		for (int i = mAppTokens.size() - 1; i >= 0; --i) {
		final AppWindowToken token = mAppTokens.get(i);
		final int orientation = token.getOrientation();

		if (orientation == SCREEN_ORIENTATION_BEHIND) {
		candidate = orientation;
		continue;
		}

		if (orientation != SCREEN_ORIENTATION_UNSET) {
		if (token.fillsParent() \|\| orientation != SCREEN_ORIENTATION_UNSPECIFIED) {
		return orientation;
		}
		}
		}

		return candidate;
		}

		@Override
		public String toString() {
		return "{taskId=" + mTaskId + " appTokens=" + mAppTokens + " mdr=" + mDeferRemoval + "}";
		return "{taskId=" + mTaskId + " appTokens=" + mChildren + " mdr=" + mDeferRemoval + "}";
		}

		String getName() {
		@@ -816,15 +656,6 @@ class Task implements DimLayer.DimLayerUser {
		return "Task=" + mTaskId;
		}

		void dumpChildrenNames(PrintWriter pw, String prefix) {
		final String childPrefix = prefix + prefix;
		for (int i = mAppTokens.size() - 1; i >= 0; --i) {
		final AppWindowToken token = mAppTokens.get(i);
		pw.println("#" + i + " " + getName());
		token.dumpChildrenNames(pw, childPrefix);
		}
		}

		public void dump(String prefix, PrintWriter pw) {
		final String doublePrefix = prefix + " ";

		@@ -832,13 +663,13 @@ class Task implements DimLayer.DimLayerUser {
		pw.println(doublePrefix + "mFullscreen=" + mFullscreen);
		pw.println(doublePrefix + "mBounds=" + mBounds.toShortString());
		pw.println(doublePrefix + "mdr=" + mDeferRemoval);
		pw.println(doublePrefix + "appTokens=" + mAppTokens);
		pw.println(doublePrefix + "appTokens=" + mChildren);
		pw.println(doublePrefix + "mTempInsetBounds=" + mTempInsetBounds.toShortString());

		final String triplePrefix = doublePrefix + " ";

		for (int i = mAppTokens.size() - 1; i >= 0; i--) {
		final AppWindowToken wtoken = mAppTokens.get(i);
		for (int i = mChildren.size() - 1; i >= 0; i--) {
		final AppWindowToken wtoken = mChildren.get(i);
		pw.println(triplePrefix + "Activity #" + i + " " + wtoken);
		wtoken.dump(pw, triplePrefix);
		}

services/core/java/com/android/server/wm/TaskStack.java

+3 −3

Original line number	Diff line number	Diff line
		@@ -116,7 +116,7 @@ public class TaskStack implements DimLayer.DimLayerUser,
		final AppTokenList mExitingAppTokens = new AppTokenList();

		/** Detach this stack from its display when animation completes. */
		// TODO: maybe tie this to WindowContainer#detachChild some how...
		// TODO: maybe tie this to WindowContainer#removeChild some how...
		boolean mDeferDetach;

		private final Rect mTmpAdjustedBounds = new Rect();
		@@ -1508,9 +1508,9 @@ public class TaskStack implements DimLayer.DimLayerUser,
		final Task secondTask = second.mTask;

		if (firstTask == secondTask) {
		return firstTask.isFirstGreaterThanSecond(first, second);
		return first.compareTo(second) > 0;
		}
		return mTasks.indexOf(first) > mTasks.indexOf(second);
		return mTasks.indexOf(firstTask) > mTasks.indexOf(secondTask);
		}

		int rebuildWindowList(DisplayContent dc, int addIndex) {

services/core/java/com/android/server/wm/WindowContainer.java

+46 −18

Original line number	Diff line number	Diff line
		@@ -17,6 +17,7 @@
		package com.android.server.wm;

		import android.annotation.CallSuper;
		import android.view.animation.Animation;

		import java.io.PrintWriter;
		import java.util.Comparator;
		@@ -61,6 +62,11 @@ class WindowContainer<E extends WindowContainer> implements Comparable<WindowCon
		*/
		@CallSuper
		protected void addChild(E child, Comparator<E> comparator) {
		if (child.mParent != null) {
		throw new IllegalArgumentException("addChild: container=" + child
		+ " is already a child of container=" + child.mParent
		+ " can't add to container=" + this);
		}
		child.mParent = this;

		if (mChildren.isEmpty() \|\| comparator == null) {
		@@ -79,6 +85,33 @@ class WindowContainer<E extends WindowContainer> implements Comparable<WindowCon
		mChildren.add(child);
		}

		/** Adds the input window container has a child of this container at the input index. */
		@CallSuper
		protected void addChild(E child, int index) {
		if (child.mParent != null) {
		throw new IllegalArgumentException("addChild: container=" + child
		+ " is already a child of container=" + child.mParent
		+ " can't add to container=" + this);
		}
		child.mParent = this;
		mChildren.add(index, child);
		}

		/**
		* Removes the input child container from this container which is its parent.
		*
		* @return True if the container did contain the input child and it was detached.
		*/
		@CallSuper
		void removeChild(E child) {
		if (mChildren.remove(child)) {
		child.mParent = null;
		} else {
		throw new IllegalArgumentException("removeChild: container=" + child
		+ " is not a child of container=" + this);
		}
		}

		/**
		* Removes this window container and its children with no regard for what else might be going on
		* in the system. For example, the container will be removed during animation if this method is
		@@ -97,7 +130,7 @@ class WindowContainer<E extends WindowContainer> implements Comparable<WindowCon
		}

		if (mParent != null) {
		mParent.detachChild(this);
		mParent.removeChild(this);
		}
		}

		@@ -115,17 +148,6 @@ class WindowContainer<E extends WindowContainer> implements Comparable<WindowCon
		}
		}

		/** Detaches the input child container from this container which is its parent. */
		@CallSuper
		void detachChild(WindowContainer child) {
		if (mChildren.remove(child)) {
		child.mParent = null;
		} else {
		throw new IllegalArgumentException("detachChild: container=" + child
		+ " is not a child of container=" + this);
		}
		}

		/** Returns true if this window container has the input child. */
		boolean hasChild(WindowContainer child) {
		for (int i = mChildren.size() - 1; i >= 0; --i) {
		@@ -233,10 +255,10 @@ class WindowContainer<E extends WindowContainer> implements Comparable<WindowCon
		* the container has any content to display.
		*/
		boolean isVisible() {
		// TODO: Will this be more correct if it checks the visibility of its parents? Yes.
		// That is this container is only visible if its parents are visible vs visible if it has a
		// visible child. In that case all overrides will need to call super and return false if
		// this returns false.
		// TODO: Will this be more correct if it checks the visibility of its parents?
		// It depends...For example, Tasks and Stacks are only visible if there children are visible
		// but, WindowState are not visible if there parent are not visible. Maybe have the
		// container specify which direction to treverse for for visibility?
		for (int i = mChildren.size() - 1; i >= 0; --i) {
		final WindowContainer wc = mChildren.get(i);
		if (wc.isVisible()) {
		@@ -303,6 +325,12 @@ class WindowContainer<E extends WindowContainer> implements Comparable<WindowCon
		}
		}

		void overridePlayingAppAnimations(Animation a) {
		for (int i = mChildren.size() - 1; i >= 0; i--) {
		mChildren.get(i).overridePlayingAppAnimations(a);
		}
		}

		void setOrientation(int orientation) {
		mOrientation = orientation;
		}
		@@ -386,8 +414,8 @@ class WindowContainer<E extends WindowContainer> implements Comparable<WindowCon
		}

		/**
		* Returns -1, 0, or 1 depending on if the input container is greater than, equal to, or lesser
		* than the input container in terms of z-order.
		* Returns 1, 0, or -1 depending on if this container is greater than, equal to, or lesser than
		* the input container in terms of z-order.
		*/
		@Override
		public int compareTo(WindowContainer other) {