From a2acb4f077713744a87e16205865a524f3254302 Mon Sep 17 00:00:00 2001
From: John Reck <jreck@google.com>
Date: Fri, 5 Aug 2016 07:58:37 -0700
Subject: [PATCH] Fix currentAnimationTimeMillis to use vsync time

Bug: 30674719
Change-Id: I71f51eea971e43cbe85bb0713a1c457a1b3243b3
---
 core/java/android/view/Choreographer.java     |  3 ++
 .../view/animation/AnimationUtils.java        | 34 ++++++++++++++++++-
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/core/java/android/view/Choreographer.java b/core/java/android/view/Choreographer.java
index d3db74d1ea249..3316f3aeb60b5 100644
--- a/core/java/android/view/Choreographer.java
+++ b/core/java/android/view/Choreographer.java
@@ -25,6 +25,7 @@ import android.os.SystemProperties;
 import android.os.Trace;
 import android.util.Log;
 import android.util.TimeUtils;
+import android.view.animation.AnimationUtils;
 
 import java.io.PrintWriter;
 
@@ -608,6 +609,7 @@ public final class Choreographer {
 
         try {
             Trace.traceBegin(Trace.TRACE_TAG_VIEW, "Choreographer#doFrame");
+            AnimationUtils.lockAnimationClock(frameTimeNanos / TimeUtils.NANOS_PER_MS);
 
             mFrameInfo.markInputHandlingStart();
             doCallbacks(Choreographer.CALLBACK_INPUT, frameTimeNanos);
@@ -620,6 +622,7 @@ public final class Choreographer {
 
             doCallbacks(Choreographer.CALLBACK_COMMIT, frameTimeNanos);
         } finally {
+            AnimationUtils.unlockAnimationClock();
             Trace.traceEnd(Trace.TRACE_TAG_VIEW);
         }
 
diff --git a/core/java/android/view/animation/AnimationUtils.java b/core/java/android/view/animation/AnimationUtils.java
index a54d94c5c2e32..351b6dbd66162 100644
--- a/core/java/android/view/animation/AnimationUtils.java
+++ b/core/java/android/view/animation/AnimationUtils.java
@@ -44,6 +44,31 @@ public class AnimationUtils {
     private static final int TOGETHER = 0;
     private static final int SEQUENTIALLY = 1;
 
+    private static class AnimationState {
+        boolean animationClockLocked;
+        long currentVsyncTimeMillis;
+        long lastReportedTimeMillis;
+    };
+
+    private static ThreadLocal<AnimationState> sAnimationState
+            = new ThreadLocal<AnimationState>() {
+        @Override
+        protected AnimationState initialValue() {
+            return new AnimationState();
+        }
+    };
+
+    /** @hide */
+    public static void lockAnimationClock(long vsyncMillis) {
+        AnimationState state = sAnimationState.get();
+        state.animationClockLocked = true;
+        state.currentVsyncTimeMillis = vsyncMillis;
+    }
+
+    /** @hide */
+    public static void unlockAnimationClock() {
+        sAnimationState.get().animationClockLocked = false;
+    }
 
     /**
      * Returns the current animation time in milliseconds. This time should be used when invoking
@@ -56,7 +81,14 @@ public class AnimationUtils {
      * @see android.os.SystemClock
      */
     public static long currentAnimationTimeMillis() {
-        return SystemClock.uptimeMillis();
+        AnimationState state = sAnimationState.get();
+        if (state.animationClockLocked) {
+            // It's important that time never rewinds
+            return Math.max(state.currentVsyncTimeMillis,
+                    state.lastReportedTimeMillis);
+        }
+        state.lastReportedTimeMillis = SystemClock.uptimeMillis();
+        return state.lastReportedTimeMillis;
     }
 
     /**