Add enter-animation-done callback for system windows

Existing hidden methods allow activities to be notified when their
windows have completed animating in. This change adds that capability
to system windows using a ViewTreeObserver callback since system
windows lack an activity token.

The first subsystem to use this is the UserSwitchingDialog which was
previously using a 250 msec timeout to dismiss the dialog. That
deadline was often missed leaving the user with no dialog on the
screen during the transition.

Fixes bug 16661752.

Change-Id: I70789e0d9c07112f275e76fb82850926305f290d

3 files changed, 35 insertions, 22 deletions

diff --git a/services/core/java/com/android/server/am/UserSwitchingDialog.java b/services/core/java/com/android/server/am/UserSwitchingDialog.java
index dfc8df5..36263ec 100644
--- a/services/core/java/com/android/server/am/UserSwitchingDialog.java
+++ b/services/core/java/com/android/server/am/UserSwitchingDialog.java
@@ -17,17 +17,11 @@
 package com.android.server.am;
 
 import android.app.AlertDialog;
-import android.app.Service;
-import android.content.ActivityNotFoundException;
 import android.content.Context;
-import android.content.DialogInterface;
-import android.content.Intent;
 import android.content.res.Resources;
-import android.os.Handler;
-import android.os.Message;
-import android.util.Slog;
 import android.view.LayoutInflater;
 import android.view.View;
+import android.view.ViewTreeObserver;
 import android.view.WindowManager;
 import android.widget.TextView;
 
@@ -39,11 +33,10 @@ import com.android.internal.R;
  * in the background rather than just freeze the screen and not know if the user-switch affordance
  * was being handled.
  */
-final class UserSwitchingDialog extends AlertDialog {
+final class UserSwitchingDialog extends AlertDialog
+        implements ViewTreeObserver.OnWindowShownListener {
     private static final String TAG = "ActivityManagerUserSwitchingDialog";
 
-    private static final int MSG_START_USER = 1;
-
     private final ActivityManagerService mService;
     private final int mUserId;
 
@@ -74,19 +67,21 @@ final class UserSwitchingDialog extends AlertDialog {
 
     @Override
     public void show() {
+        // Slog.v(TAG, "show called");
         super.show();
-        // TODO: Instead of just an arbitrary delay, wait for a signal that the window was fully
-        // displayed by the window manager
-        mHandler.sendMessageDelayed(mHandler.obtainMessage(MSG_START_USER), 250);
+        final View decorView = getWindow().getDecorView();
+        if (decorView != null) {
+            decorView.getViewTreeObserver().addOnWindowShownListener(this);
+        }
     }
 
-    private final Handler mHandler = new Handler() {
-        public void handleMessage(Message msg) {
-            switch (msg.what) {
-                case MSG_START_USER:
-                    mService.startUserInForeground(mUserId, UserSwitchingDialog.this);
-                    break;
-            }
+    @Override
+    public void onWindowShown() {
+        // Slog.v(TAG, "onWindowShown called");
+        mService.startUserInForeground(mUserId, this);
+        final View decorView = getWindow().getDecorView();
+        if (decorView != null) {
+            decorView.getViewTreeObserver().removeOnWindowShownListener(this);
         }
-    };
+    }
 }
diff --git a/services/core/java/com/android/server/wm/WindowManagerService.java b/services/core/java/com/android/server/wm/WindowManagerService.java
index 0e55c1c..8c4e7b0 100644
--- a/services/core/java/com/android/server/wm/WindowManagerService.java
+++ b/services/core/java/com/android/server/wm/WindowManagerService.java
@@ -2487,7 +2487,9 @@ public class WindowManagerService extends IWindowManager.Stub
                 }
             }
 
-            win.mWinAnimator.mEnterAnimationPending = true;
+            final WindowStateAnimator winAnimator = win.mWinAnimator;
+            winAnimator.mEnterAnimationPending = true;
+            winAnimator.mEnteringAnimation = true;
 
             if (displayContent.isDefaultDisplay) {
                 mPolicy.getContentInsetHintLw(attrs, outContentInsets);
@@ -3099,6 +3101,7 @@ public class WindowManagerService extends IWindowManager.Stub
                 if (oldVisibility == View.GONE) {
                     winAnimator.mEnterAnimationPending = true;
                 }
+                winAnimator.mEnteringAnimation = true;
                 if (toBeDisplayed) {
                     if (win.isDrawnLw() && okToDisplay()) {
                         winAnimator.applyEnterAnimationLocked();
@@ -3167,6 +3170,7 @@ public class WindowManagerService extends IWindowManager.Stub
                 }
             } else {
                 winAnimator.mEnterAnimationPending = false;
+                winAnimator.mEnteringAnimation = false;
                 if (winAnimator.mSurfaceControl != null) {
                     if (DEBUG_VISIBILITY) Slog.i(TAG, "Relayout invis " + win
                             + ": mExiting=" + win.mExiting);
diff --git a/services/core/java/com/android/server/wm/WindowStateAnimator.java b/services/core/java/com/android/server/wm/WindowStateAnimator.java
index 0c727f3..fc3f2c2 100644
--- a/services/core/java/com/android/server/wm/WindowStateAnimator.java
+++ b/services/core/java/com/android/server/wm/WindowStateAnimator.java
@@ -40,6 +40,7 @@ import android.graphics.Rect;
 import android.graphics.RectF;
 import android.graphics.Region;
 import android.os.Debug;
+import android.os.RemoteException;
 import android.os.UserHandle;
 import android.util.Slog;
 import android.view.Display;
@@ -141,6 +142,11 @@ class WindowStateAnimator {
     // an enter animation.
     boolean mEnterAnimationPending;
 
+    /** Used to indicate that this window is undergoing an enter animation. Used for system
+     * windows to make the callback to View.dispatchOnWindowShownCallback(). Set when the
+     * window is first added or shown, cleared when the callback has been made. */
+    boolean mEnteringAnimation;
+
     boolean keyguardGoingAwayAnimation;
 
     /** This is set when there is no Surface */
@@ -428,6 +434,14 @@ class WindowStateAnimator {
             mWin.mChildWindows.get(i).mWinAnimator.finishExit();
         }
 
+        if (mEnteringAnimation && mWin.mAppToken == null) {
+            try {
+                mEnteringAnimation = false;
+                mWin.mClient.dispatchWindowShown();
+            } catch (RemoteException e) {
+            }
+        }
+
         if (!mWin.mExiting) {
             return;
         }