Fixing misc issues that leads to black screen when pressing Home

- Make sure to clear usingTransferredAnimation flag together when
  setting app animator's animation to null. Not clearing it will cause
  setAppVisibility to not apply dummy animation (placeholder)
  to a closing app token while it should, and the closing app token will
  then exit early before the opening app is ready, since it doesn't have
  any animation set. This causes a brief blank period.

- When app relayout to invisible, make sure to mark mWinAnimator's
  mAnimating to true if we decided exit animation is running. Note that
  even if we didn't actually apply the animation (which could happen if
  the window is no longer visible by policy), if the app token itself is
  under any animation, we need to mark mAnimating otherwise the clean up
  code in FinishExit will not run, and the window will be stuck in
  Exiting state.

- We no longer change mAnimatingExit flag in setAppVisibility(), but
  wait for app's relayoutWindow calls to change it if applicable.
  setAppVisibilty doesn't apply the animation until transition is good
  to go. Setting the flag without the animation applied will disable
  setTokenVisibilityLocked and relayoutWindow to actually apply the
  animation, because they may think the window is no longer visible.

bug: 27391256

Change-Id: I292305847d742cdbb5ebe6aa8daa5d83bf65483b

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

@@ -171,17 +171,21 @@ public class AppWindowAnimator {
         transformation.setAlpha(mAppToken.isVisible() ? 1 : 0);
     }
 
+    void setNullAnimation() {
+        animation = null;
+        usingTransferredAnimation = false;
+    }
+
     public void clearAnimation() {
         if (animation != null) {
-            animation = null;
             animating = true;
         }
         clearThumbnail();
+        setNullAnimation();
         if (mAppToken.deferClearAllDrawn) {
             mAppToken.allDrawn = false;
             mAppToken.deferClearAllDrawn = false;
         }
-        usingTransferredAnimation = false;
     }
 
     public boolean isAnimating() {
@@ -202,9 +206,9 @@ public class AppWindowAnimator {
 
         if (animation != null) {
             toAppAnimator.animation = animation;
-            animation = null;
             toAppAnimator.animating = animating;
             toAppAnimator.animLayerAdjustment = animLayerAdjustment;
+            setNullAnimation();
             animLayerAdjustment = 0;
             toAppAnimator.updateLayers();
             updateLayers();
@@ -311,7 +315,7 @@ public class AppWindowAnimator {
                 if (mProlongAnimation == PROLONG_ANIMATION_AT_END) {
                     hasMoreFrames = true;
                 } else {
-                    animation = null;
+                    setNullAnimation();
                     clearThumbnail();
                     if (DEBUG_ANIM) Slog.v(TAG, "Finished animation in " + mAppToken + " @ "
                             + currentTime);

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

@@ -322,23 +322,6 @@ class AppWindowToken extends WindowToken {
         }
     }
 
-    void setWindowsExiting(boolean exiting) {
-        for (int i = allAppWindows.size() - 1; i >= 0; i--) {
-            WindowState win = allAppWindows.get(i);
-            // If the app already requested to remove its window, we don't modify
-            // its exiting state. Otherwise the stale window won't get removed on
-            // exit and could cause focus to be given to the wrong window.
-            if (!(win.mRemoveOnExit && win.mAnimatingExit)) {
-                win.mAnimatingExit = exiting;
-            }
-            // If we're no longer exiting, remove the window from destroying list
-            if (!win.mAnimatingExit && win.mDestroying) {
-                win.mDestroying = false;
-                service.mDestroySurface.remove(win);
-            }
-        }
-    }
-
     // Here we destroy surfaces which have been marked as eligible by the animator, taking care
     // to ensure the client has finished with them. If the client could still be using them
     // we will skip destruction and try again when the client has stopped.

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

@@ -2825,10 +2825,12 @@ public class WindowManagerService extends IWindowManager.Stub
         if (win.isWinVisibleLw() && winAnimator.applyAnimationLocked(transit, false)) {
             focusMayChange = isDefaultDisplay;
             win.mAnimatingExit = true;
+            win.mWinAnimator.mAnimating = true;
         } else if (win.mWinAnimator.isAnimating()) {
             // Currently in a hide animation... turn this into
             // an exit.
             win.mAnimatingExit = true;
+            win.mWinAnimator.mAnimating = true;
         } else if (mWallpaperControllerLocked.isWallpaperTarget(win)) {
             // If the wallpaper is currently behind this
             // window, we need to change both of them inside
@@ -4085,7 +4087,7 @@ public class WindowManagerService extends IWindowManager.Stub
 
             if (transit != AppTransition.TRANSIT_UNSET) {
                 if (wtoken.mAppAnimator.animation == AppWindowAnimator.sDummyAnimation) {
-                    wtoken.mAppAnimator.animation = null;
+                    wtoken.mAppAnimator.setNullAnimation();
                 }
                 if (applyAnimationLocked(wtoken, lp, transit, visible, isVoiceInteraction)) {
                     delayed = runningAppAnimation = true;
@@ -4195,7 +4197,7 @@ public class WindowManagerService extends IWindowManager.Stub
     void updateTokenInPlaceLocked(AppWindowToken wtoken, int transit) {
         if (transit != AppTransition.TRANSIT_UNSET) {
             if (wtoken.mAppAnimator.animation == AppWindowAnimator.sDummyAnimation) {
-                wtoken.mAppAnimator.animation = null;
+                wtoken.mAppAnimator.setNullAnimation();
             }
             applyAnimationLocked(wtoken, null, transit, false, false);
         }
@@ -4255,7 +4257,6 @@ public class WindowManagerService extends IWindowManager.Stub
                 if (DEBUG_ADD_REMOVE) Slog.v(
                         TAG_WM, "No longer Stopped: " + wtoken);
                 wtoken.mAppStopped = false;
-                wtoken.setWindowsExiting(false);
                 mOpeningApps.add(wtoken);
                 wtoken.startingMoved = false;
 
@@ -4287,6 +4288,11 @@ public class WindowManagerService extends IWindowManager.Stub
                 // animation is going on (in this case an application transition). If the animation
                 // was transferred from another application/animator, no dummy animator should be
                 // created since an animation is already in progress.
+                if (wtoken.mAppAnimator.usingTransferredAnimation
+                        && wtoken.mAppAnimator.animation == null) {
+                    Slog.wtf(TAG_WM, "Will NOT set dummy animation on: " + wtoken
+                            + ", using null transfered animation!");
+                }
                 if (!wtoken.mAppAnimator.usingTransferredAnimation &&
                         (!wtoken.startingDisplayed || mSkipAppTransitionAnimation)) {
                     if (DEBUG_APP_TRANSITIONS) Slog.v(
@@ -4297,7 +4303,6 @@ public class WindowManagerService extends IWindowManager.Stub
                 if (visible) {
                     wtoken.mEnteringAnimation = true;
                 } else {
-                    wtoken.setWindowsExiting(true);
                     mClosingApps.add(wtoken);
                     wtoken.mEnteringAnimation = false;
                 }

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

@@ -670,8 +670,8 @@ final class WindowState implements WindowManagerPolicy.WindowState {
             }
 
             if (windowsAreFloating) {
-                // In floating modes (e.g. freeform, pinned) we have only to set the rectangle 
-                // if it wasn't set already. No need to intersect it with the (visible) 
+                // In floating modes (e.g. freeform, pinned) we have only to set the rectangle
+                // if it wasn't set already. No need to intersect it with the (visible)
                 // "content frame" since it is allowed to be outside the visible desktop.
                 if (mContainingFrame.isEmpty()) {
                     mContainingFrame.set(cf);

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

@@ -1158,7 +1158,7 @@ class WindowSurfacePlacer {
 
             if (!appAnimator.usingTransferredAnimation) {
                 appAnimator.clearThumbnail();
-                appAnimator.animation = null;
+                appAnimator.setNullAnimation();
             }
             wtoken.inPendingTransaction = false;
 
@@ -1231,7 +1231,7 @@ class WindowSurfacePlacer {
             final AppWindowAnimator appAnimator = wtoken.mAppAnimator;
             if (DEBUG_APP_TRANSITIONS) Slog.v(TAG, "Now closing app " + wtoken);
             appAnimator.clearThumbnail();
-            appAnimator.animation = null;
+            appAnimator.setNullAnimation();
             wtoken.inPendingTransaction = false;
             mService.setTokenVisibilityLocked(wtoken, animLp, false, transit, false,
                     voiceInteraction);
@@ -1494,7 +1494,7 @@ class WindowSurfacePlacer {
                 if (DEBUG_APP_TRANSITIONS)
                     Slog.v(TAG, "Now animating app in place " + wtoken);
                 appAnimator.clearThumbnail();
-                appAnimator.animation = null;
+                appAnimator.setNullAnimation();
                 mService.updateTokenInPlaceLocked(wtoken, transit);
                 wtoken.updateReportedVisibilityLocked();