Merge "Improve animation timing." into jb-dev

Author: Jeff Brown

core/java/android/animation/ValueAnimator.java

@@ -910,7 +910,7 @@ private void start(boolean playBackwards) {
         animationHandler.mPendingAnimations.add(this);
         if (mStartDelay == 0) {
             // This sets the initial value of the animation, prior to actually starting it running
-            setCurrentPlayTime(getCurrentPlayTime());
+            setCurrentPlayTime(0);
             mPlayingState = STOPPED;
             mRunning = true;
             notifyStartListeners();

core/java/android/view/Choreographer.java

@@ -92,6 +92,7 @@ protected Choreographer initialValue() {
     private boolean mFrameScheduled;
     private boolean mCallbacksRunning;
     private long mLastFrameTimeNanos;
+    private long mFrameIntervalNanos;
 
     /**
      * Callback type: Input callback.  Runs first.
@@ -116,6 +117,8 @@ private Choreographer(Looper looper) {
         mHandler = new FrameHandler(looper);
         mDisplayEventReceiver = USE_VSYNC ? new FrameDisplayEventReceiver(looper) : null;
         mLastFrameTimeNanos = Long.MIN_VALUE;
+        mFrameIntervalNanos = (long)(1000000000 /
+                new Display(Display.DEFAULT_DISPLAY, null).getRefreshRate());
 
         mCallbackQueues = new CallbackQueue[CALLBACK_LAST + 1];
         for (int i = 0; i <= CALLBACK_LAST; i++) {
@@ -343,17 +346,37 @@ private void scheduleFrameLocked(long now) {
     }
 
     void doFrame(long timestampNanos, int frame) {
+        final long startNanos;
         synchronized (mLock) {
             if (!mFrameScheduled) {
                 return; // no work to do
             }
-            mFrameScheduled = false;
-            mLastFrameTimeNanos = timestampNanos;
-        }
 
-        final long startNanos;
-        if (DEBUG) {
             startNanos = System.nanoTime();
+            final long jitterNanos = startNanos - timestampNanos;
+            if (jitterNanos >= mFrameIntervalNanos) {
+                final long lastFrameOffset = jitterNanos % mFrameIntervalNanos;
+                if (DEBUG) {
+                    Log.d(TAG, "Missed vsync by " + (jitterNanos * 0.000001f) + " ms "
+                            + "which is more than the frame interval of "
+                            + (mFrameIntervalNanos * 0.000001f) + " ms!  "
+                            + "Setting frame time to " + (lastFrameOffset * 0.000001f)
+                            + " ms in the past.");
+                }
+                timestampNanos = startNanos - lastFrameOffset;
+            }
+
+            if (timestampNanos < mLastFrameTimeNanos) {
+                if (DEBUG) {
+                    Log.d(TAG, "Frame time appears to be going backwards.  May be due to a "
+                            + "previously skipped frame.  Waiting for next vsync");
+                }
+                scheduleVsyncLocked();
+                return;
+            }
+
+            mFrameScheduled = false;
+            mLastFrameTimeNanos = timestampNanos;
         }
 
         doCallbacks(Choreographer.CALLBACK_INPUT);