From 58606db8be7e64a4317955b87fba4ee51f353630 Mon Sep 17 00:00:00 2001
From: Doris Liu <tianliu@google.com>
Date: Wed, 13 Apr 2016 13:28:38 -0700
Subject: [PATCH] Add api check to guard AnimatorSet behavior change

For pre-N, we have inconsistent behavior between ValueAnimator and
AnimatorSet in the case of calling end() when already ended:
ValueAnimator would start() and immediately end, whereas AnimatorSet
would be no-op. We made a decision to be consistent within Animation
Framework from N forward, which means that AnimatorSet will have the
new behavior of starting and immediately ending just like
ValueAnimator. This new behavior will be guarded by an API check.

Bug: 25601129
Change-Id: I2d952a93d8521c547ec8cde173c80d1d8ead0639
---
 core/java/android/animation/AnimatorSet.java | 21 ++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/core/java/android/animation/AnimatorSet.java b/core/java/android/animation/AnimatorSet.java
index 3385a17002bce..e788d2749d172 100644
--- a/core/java/android/animation/AnimatorSet.java
+++ b/core/java/android/animation/AnimatorSet.java
@@ -16,6 +16,9 @@
 
 package android.animation;
 
+import android.app.ActivityThread;
+import android.app.Application;
+import android.os.Build;
 import android.util.ArrayMap;
 import android.util.Log;
 
@@ -133,10 +136,25 @@ public final class AnimatorSet extends Animator {
     // The total duration of finishing all the Animators in the set.
     private long mTotalDuration = 0;
 
+    // In pre-N releases, calling end() before start() on an animator set is no-op. But that is not
+    // consistent with the behavior for other animator types. In order to keep the behavior
+    // consistent within Animation framework, when end() is called without start(), we will start
+    // the animator set and immediately end it for N and forward.
+    private final boolean mShouldIgnoreEndWithoutStart;
+
     public AnimatorSet() {
         super();
         mNodeMap.put(mDelayAnim, mRootNode);
         mNodes.add(mRootNode);
+        // Set the flag to ignore calling end() without start() for pre-N releases
+        Application app = ActivityThread.currentApplication();
+        if (app == null || app.getApplicationInfo() == null) {
+            mShouldIgnoreEndWithoutStart = true;
+        } else if (app.getApplicationInfo().targetSdkVersion < Build.VERSION_CODES.N) {
+            mShouldIgnoreEndWithoutStart = true;
+        } else {
+            mShouldIgnoreEndWithoutStart = false;
+        }
     }
 
     /**
@@ -365,6 +383,9 @@ public final class AnimatorSet extends Animator {
      */
     @Override
     public void end() {
+        if (mShouldIgnoreEndWithoutStart && !isStarted()) {
+            return;
+        }
         mTerminated = true;
         if (isStarted()) {
             endRemainingAnimations();