From 7114215648b5d27a23648458a6b5b476bdf8f7d9 Mon Sep 17 00:00:00 2001
From: Issei Suzuki <issei@google.com>
Date: Thu, 15 Aug 2019 14:39:40 +0200
Subject: [PATCH] Stop reparenting surfaces during app transtion animation.

This is a first step to restructure the app transition, and the change is
behind the flag persist.wm.new_transit_animations.

Bug: 131661052
Change-Id: I9a23440c6c5d28ea937121e95985b3bd6f3cc451
Test: No-op for production. Pass existing tests.
---
 .../com/android/server/wm/AppWindowToken.java    | 14 +++++++++-----
 .../core/java/com/android/server/wm/Task.java    |  3 +++
 .../android/server/wm/WindowManagerService.java  | 16 ++++++++++++++++
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/services/core/java/com/android/server/wm/AppWindowToken.java b/services/core/java/com/android/server/wm/AppWindowToken.java
index ffd9021989b46..93b8f0022f79e 100644
--- a/services/core/java/com/android/server/wm/AppWindowToken.java
+++ b/services/core/java/com/android/server/wm/AppWindowToken.java
@@ -2503,14 +2503,18 @@ class AppWindowToken extends WindowToken implements WindowManagerService.AppFree
 
     @Override
     public SurfaceControl getAnimationLeashParent() {
-        // All normal app transitions take place in an animation layer which is below the pinned
-        // stack but may be above the parent stacks of the given animating apps.
         // For transitions in the pinned stack (menu activity) we just let them occur as a child
         // of the pinned stack.
-        if (!inPinnedWindowingMode()) {
-            return getAppAnimationLayer();
-        } else {
+        // All normal app transitions take place in an animation layer which is below the pinned
+        // stack but may be above the parent stacks of the given animating apps by default. When
+        // a new hierarchical animation is enabled, we just let them occur as a child of the parent
+        // stack, i.e. the hierarchy of the surfaces is unchanged.
+        if (inPinnedWindowingMode()) {
             return getStack().getSurfaceControl();
+        } else if (WindowManagerService.sHierarchicalAnimations) {
+            return super.getAnimationLeashParent();
+        } else {
+            return getAppAnimationLayer();
         }
     }
 
diff --git a/services/core/java/com/android/server/wm/Task.java b/services/core/java/com/android/server/wm/Task.java
index 3a2eb57f1d80b..762066c1f80ab 100644
--- a/services/core/java/com/android/server/wm/Task.java
+++ b/services/core/java/com/android/server/wm/Task.java
@@ -613,6 +613,9 @@ class Task extends WindowContainer<AppWindowToken> implements ConfigurationConta
 
     @Override
     public SurfaceControl getAnimationLeashParent() {
+        if (!WindowManagerService.sHierarchicalAnimations) {
+            return super.getAnimationLeashParent();
+        }
         // Currently, only the recents animation will create animation leashes for tasks. In this
         // case, reparent the task to the home animation layer while it is being animated to allow
         // the home activity to reorder the app windows relative to its own.
diff --git a/services/core/java/com/android/server/wm/WindowManagerService.java b/services/core/java/com/android/server/wm/WindowManagerService.java
index 8d3a107c2f253..774c6e708c79a 100644
--- a/services/core/java/com/android/server/wm/WindowManagerService.java
+++ b/services/core/java/com/android/server/wm/WindowManagerService.java
@@ -376,6 +376,22 @@ public class WindowManagerService extends IWindowManager.Stub
     // trying to apply a new one.
     private static final boolean ALWAYS_KEEP_CURRENT = true;
 
+    /**
+     * If set, new app transition framework which supports setting animation on any element
+     * in a surface is used.
+     * <p>
+     * Only set this to non-zero once the new app transition framework is productionalized.
+     * </p>
+     */
+    private static final String HIERARCHICAL_ANIMATIONS_PROPERTY =
+            "persist.wm.hierarchical_animations";
+
+    /**
+     * @see #HIERARCHICAL_ANIMATIONS_PROPERTY
+     */
+    static boolean sHierarchicalAnimations =
+            SystemProperties.getBoolean(HIERARCHICAL_ANIMATIONS_PROPERTY, false);
+
     // Enums for animation scale update types.
     @Retention(RetentionPolicy.SOURCE)
     @IntDef({WINDOW_ANIMATION_SCALE, TRANSITION_ANIMATION_SCALE, ANIMATION_DURATION_SCALE})