Allow system to disable behavior of pausing animators for bg apps am: 161732cf18

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/18527682

Change-Id: Iab25efc6926ec409ac93769c2d76c88cf8b5bcb6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

core/api/test-current.txt

@@ -98,6 +98,7 @@ package android.animation {
 
   public abstract class Animator implements java.lang.Cloneable {
     method public static long getBackgroundPauseDelay();
+    method public static void setAnimatorPausingEnabled(boolean);
     method public static void setBackgroundPauseDelay(long);
   }
 

core/java/android/animation/AnimationHandler.java

@@ -53,6 +53,9 @@ public class AnimationHandler {
             new ArrayList<>();
     private AnimationFrameCallbackProvider mProvider;
 
+    // Static flag which allows the pausing behavior to be globally disabled/enabled.
+    private static boolean sAnimatorPausingEnabled = true;
+
     /**
      * This paused list is used to store animators forcibly paused when the activity
      * went into the background (to avoid unnecessary background processing work).
@@ -93,6 +96,15 @@ public class AnimationHandler {
         return sAnimatorHandler.get();
     }
 
+    /**
+     * Disable the default behavior of pausing infinite animators when
+     * apps go into the background.
+     *
+     * @param enable Enable (default behavior) or disable background pausing behavior.
+     */
+    public static void setAnimatorPausingEnabled(boolean enable) {
+        sAnimatorPausingEnabled = enable;
+    }
 
     /**
      * This is called when a window goes away. We should remove
@@ -136,16 +148,19 @@ public class AnimationHandler {
         } else {
             mAnimatorRequestors.remove(requestor);
         }
+        if (!sAnimatorPausingEnabled) {
+            // Resume any animators that have been paused in the meantime, otherwise noop
+            // Leave logic above so that if pausing gets re-enabled, the state of the requestors
+            // list is valid
+            resumeAnimators();
+            return;
+        }
         boolean isEmpty = mAnimatorRequestors.isEmpty();
         if (wasEmpty != isEmpty) {
             // only paused/resume animators if there was a visibility change
             if (!isEmpty) {
                 // If any requestors are enabled, resume currently paused animators
-                Choreographer.getInstance().removeFrameCallback(mPauser);
+                resumeAnimators();
-                for (int i = mPausedAnimators.size() - 1; i >= 0; --i) {
-                    mPausedAnimators.get(i).resume();
-                }
-                mPausedAnimators.clear();
             } else {
                 // Wait before pausing to avoid thrashing animator state for temporary backgrounding
                 Choreographer.getInstance().postFrameCallbackDelayed(mPauser,
@@ -160,6 +175,14 @@ public class AnimationHandler {
         }
     }
 
+    private void resumeAnimators() {
+        Choreographer.getInstance().removeFrameCallback(mPauser);
+        for (int i = mPausedAnimators.size() - 1; i >= 0; --i) {
+            mPausedAnimators.get(i).resume();
+        }
+        mPausedAnimators.clear();
+    }
+
     private Choreographer.FrameCallback mPauser = frameTimeNanos -> {
         if (mAnimatorRequestors.size() > 0) {
             // something enabled animators since this callback was scheduled - bail

core/java/android/animation/Animator.java

@@ -92,6 +92,20 @@ public abstract class Animator implements Cloneable {
         return sBackgroundPauseDelay;
     }
 
+    /**
+     * Sets the behavior of animator pausing when apps go into the background.
+     * This is exposed as a test API for verification, but is intended for use by internal/
+     * platform code, potentially for use by a system property that could disable it
+     * system wide.
+     *
+     * @param enable Enable (default behavior) or disable background pausing behavior.
+     * @hide
+     */
+    @TestApi
+    public static void setAnimatorPausingEnabled(boolean enable) {
+        AnimationHandler.setAnimatorPausingEnabled(enable);
+    }
+
     /**
      * Starts this animation. If the animation has a nonzero startDelay, the animation will start
      * running after that delay elapses. A non-delayed animation will have its initial