VectorDrawable native rendering - Step 5 of MANY

This is reverting the revert of what reverts the revert of the original
implementation. Fourth revert is a charm!

This reverts commit df7fdb1e0bdb5c289bbc08047e5c710185503309.

Change-Id: I6fc3a5accfd8b79c3da31bbc101ad9e9b4d6e7dd

10 files changed, 304 insertions, 169 deletions

diff --git a/core/java/android/animation/AnimatorSet.java b/core/java/android/animation/AnimatorSet.java
index 980329fe31c8..3385a17002bc 100644
--- a/core/java/android/animation/AnimatorSet.java
+++ b/core/java/android/animation/AnimatorSet.java
@@ -807,6 +807,8 @@ public final class AnimatorSet extends Animator {
     }
 
     /**
+     * AnimatorSet is only reversible when the set contains no sequential animation, and no child
+     * animators have a start delay.
      * @hide
      */
     @Override
diff --git a/core/jni/android_graphics_drawable_AnimatedVectorDrawable.cpp b/core/jni/android_graphics_drawable_AnimatedVectorDrawable.cpp
index 7a3c598e0aed..14badb72a195 100644
--- a/core/jni/android_graphics_drawable_AnimatedVectorDrawable.cpp
+++ b/core/jni/android_graphics_drawable_AnimatedVectorDrawable.cpp
@@ -43,12 +43,13 @@ static JNIEnv* getEnv(JavaVM* vm) {
     return env;
 }
 
-static AnimationListener* createAnimationListener(JNIEnv* env, jobject finishListener) {
+static AnimationListener* createAnimationListener(JNIEnv* env, jobject finishListener, jint id) {
     class AnimationListenerBridge : public AnimationListener {
     public:
-        AnimationListenerBridge(JNIEnv* env, jobject finishListener) {
+        AnimationListenerBridge(JNIEnv* env, jobject finishListener, jint id) {
             mFinishListener = env->NewGlobalRef(finishListener);
             env->GetJavaVM(&mJvm);
+            mId = id;
         }
 
         virtual ~AnimationListenerBridge() {
@@ -63,7 +64,7 @@ static AnimationListener* createAnimationListener(JNIEnv* env, jobject finishLis
             env->CallStaticVoidMethod(
                     gVectorDrawableAnimatorClassInfo.clazz,
                     gVectorDrawableAnimatorClassInfo.callOnFinished,
-                    mFinishListener);
+                    mFinishListener, mId);
             releaseJavaObject();
         }
 
@@ -76,8 +77,9 @@ static AnimationListener* createAnimationListener(JNIEnv* env, jobject finishLis
 
         JavaVM* mJvm;
         jobject mFinishListener;
+        jint mId;
     };
-    return new AnimationListenerBridge(env, finishListener);
+    return new AnimationListenerBridge(env, finishListener, id);
 }
 
 static void addAnimator(JNIEnv*, jobject, jlong animatorSetPtr, jlong propertyHolderPtr,
@@ -142,15 +144,16 @@ static void setPropertyHolderData(JNIEnv* env, jobject, jlong propertyHolderPtr,
     holder->setPropertyDataSource(propertyData, length);
     env->ReleaseFloatArrayElements(srcData, propertyData, JNI_ABORT);
 }
-static void start(JNIEnv* env, jobject, jlong animatorSetPtr, jobject finishListener) {
+static void start(JNIEnv* env, jobject, jlong animatorSetPtr, jobject finishListener, jint id) {
     PropertyValuesAnimatorSet* set = reinterpret_cast<PropertyValuesAnimatorSet*>(animatorSetPtr);
-    // TODO: keep a ref count in finish listener
-    AnimationListener* listener = createAnimationListener(env, finishListener);
+    AnimationListener* listener = createAnimationListener(env, finishListener, id);
     set->start(listener);
 }
 
-static void reverse(JNIEnv* env, jobject, jlong animatorSetPtr, jobject finishListener) {
-    // TODO: implement reverse
+static void reverse(JNIEnv* env, jobject, jlong animatorSetPtr, jobject finishListener, jint id) {
+    PropertyValuesAnimatorSet* set = reinterpret_cast<PropertyValuesAnimatorSet*>(animatorSetPtr);
+    AnimationListener* listener = createAnimationListener(env, finishListener, id);
+    set->reverse(listener);
 }
 
 static void end(JNIEnv*, jobject, jlong animatorSetPtr) {
@@ -172,8 +175,8 @@ static const JNINativeMethod gMethods[] = {
     {"nCreatePathPropertyHolder", "!(JIFF)J", (void*)createPathPropertyHolder},
     {"nCreateRootAlphaPropertyHolder", "!(JFF)J", (void*)createRootAlphaPropertyHolder},
     {"nSetPropertyHolderData", "(J[FI)V", (void*)setPropertyHolderData},
-    {"nStart", "(JLandroid/graphics/drawable/AnimatedVectorDrawable$VectorDrawableAnimator;)V", (void*)start},
-    {"nReverse", "(JLandroid/graphics/drawable/AnimatedVectorDrawable$VectorDrawableAnimator;)V", (void*)reverse},
+    {"nStart", "(JLandroid/graphics/drawable/AnimatedVectorDrawable$VectorDrawableAnimator;I)V", (void*)start},
+    {"nReverse", "(JLandroid/graphics/drawable/AnimatedVectorDrawable$VectorDrawableAnimator;I)V", (void*)reverse},
     {"nEnd", "!(J)V", (void*)end},
     {"nReset", "!(J)V", (void*)reset},
 };
@@ -186,7 +189,7 @@ int register_android_graphics_drawable_AnimatedVectorDrawable(JNIEnv* env) {
 
     gVectorDrawableAnimatorClassInfo.callOnFinished = GetStaticMethodIDOrDie(
             env, gVectorDrawableAnimatorClassInfo.clazz, "callOnFinished",
-            "(Landroid/graphics/drawable/AnimatedVectorDrawable$VectorDrawableAnimator;)V");
+            "(Landroid/graphics/drawable/AnimatedVectorDrawable$VectorDrawableAnimator;I)V");
     return RegisterMethodsOrDie(env, "android/graphics/drawable/AnimatedVectorDrawable",
             gMethods, NELEM(gMethods));
 }
diff --git a/core/jni/android_view_RenderNodeAnimator.cpp b/core/jni/android_view_RenderNodeAnimator.cpp
index 0926e9b76691..c9eac79ef9b6 100644
--- a/core/jni/android_view_RenderNodeAnimator.cpp
+++ b/core/jni/android_view_RenderNodeAnimator.cpp
@@ -184,7 +184,7 @@ static void start(JNIEnv* env, jobject clazz, jlong animatorPtr) {
 
 static void end(JNIEnv* env, jobject clazz, jlong animatorPtr) {
     BaseRenderNodeAnimator* animator = reinterpret_cast<BaseRenderNodeAnimator*>(animatorPtr);
-    animator->end();
+    animator->cancel();
 }
 
 // ----------------------------------------------------------------------------
diff --git a/graphics/java/android/graphics/drawable/AnimatedVectorDrawable.java b/graphics/java/android/graphics/drawable/AnimatedVectorDrawable.java
index af8ccf5018b9..99bc306821ef 100644
--- a/graphics/java/android/graphics/drawable/AnimatedVectorDrawable.java
+++ b/graphics/java/android/graphics/drawable/AnimatedVectorDrawable.java
@@ -238,9 +238,6 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
             mAnimatorSet.recordLastSeenTarget((DisplayListCanvas) canvas);
         }
         mAnimatedVectorState.mVectorDrawable.draw(canvas);
-        if (isStarted()) {
-            invalidateSelf();
-        }
     }
 
     @Override
@@ -611,10 +608,6 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
         return mAnimatorSet.isRunning();
     }
 
-    private boolean isStarted() {
-        return mAnimatorSet.isStarted();
-    }
-
     /**
      * Resets the AnimatedVectorDrawable to the start state as specified in the animators.
      */
@@ -626,12 +619,6 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
     @Override
     public void start() {
         ensureAnimatorSet();
-
-        // If any one of the animator has not ended, do nothing.
-        if (isStarted()) {
-            return;
-        }
-
         mAnimatorSet.start();
         invalidateSelf();
     }
@@ -652,6 +639,7 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
     @Override
     public void stop() {
         mAnimatorSet.end();
+        invalidateSelf();
     }
 
     /**
@@ -774,6 +762,9 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
      * @hide
      */
     public static class VectorDrawableAnimator {
+        private static final int NONE = 0;
+        private static final int START_ANIMATION = 1;
+        private static final int REVERSE_ANIMATION = 2;
         private AnimatorListener mListener = null;
         private final LongArray mStartDelays = new LongArray();
         private PropertyValuesHolder.PropertyValues mTmpValues =
@@ -782,7 +773,6 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
         private boolean mContainsSequentialAnimators = false;
         private boolean mStarted = false;
         private boolean mInitialized = false;
-        private boolean mAnimationPending = false;
         private boolean mIsReversible = false;
         // This needs to be set before parsing starts.
         private boolean mShouldIgnoreInvalidAnim;
@@ -790,7 +780,8 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
         private final VirtualRefBasePtr mSetRefBasePtr;
         private WeakReference<RenderNode> mTarget = null;
         private WeakReference<RenderNode> mLastSeenTarget = null;
-
+        private int mLastListenerId = 0;
+        private int mPendingAnimationAction = NONE;
 
         VectorDrawableAnimator() {
             mSetPtr = nCreateAnimatorSet();
@@ -810,6 +801,7 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
             mInitialized = true;
 
             // Check reversible.
+            mIsReversible = true;
             if (mContainsSequentialAnimators) {
                 mIsReversible = false;
             } else {
@@ -821,7 +813,6 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
                     }
                 }
             }
-            mIsReversible = true;
         }
 
         private void parseAnimatorSet(AnimatorSet set, long startTime) {
@@ -1042,27 +1033,22 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
          * to the last seen RenderNode target and start right away.
          */
         protected void recordLastSeenTarget(DisplayListCanvas canvas) {
-            if (mAnimationPending) {
-                mLastSeenTarget = new WeakReference<RenderNode>(
-                        RenderNodeAnimatorSetHelper.getTarget(canvas));
+            mLastSeenTarget = new WeakReference<RenderNode>(
+                    RenderNodeAnimatorSetHelper.getTarget(canvas));
+            if (mPendingAnimationAction != NONE) {
                 if (DBG_ANIMATION_VECTOR_DRAWABLE) {
                     Log.d(LOGTAG, "Target is set in the next frame");
                 }
-                mAnimationPending = false;
-                start();
-            } else {
-                mLastSeenTarget = new WeakReference<RenderNode>(
-                        RenderNodeAnimatorSetHelper.getTarget(canvas));
+                if (mPendingAnimationAction == START_ANIMATION) {
+                    start();
+                } else if (mPendingAnimationAction == REVERSE_ANIMATION) {
+                    reverse();
+                }
+                mPendingAnimationAction = NONE;
             }
-
         }
 
         private boolean setTarget(RenderNode node) {
-            if (mTarget != null && mTarget.get() != null) {
-                // TODO: Maybe we want to support target change.
-                throw new IllegalStateException("Target already set!");
-            }
-
             node.addAnimator(this);
             mTarget = new WeakReference<RenderNode>(node);
             return true;
@@ -1081,12 +1067,8 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
                 return;
             }
 
-            if (mStarted) {
-                return;
-            }
-
             if (!useLastSeenTarget()) {
-                mAnimationPending = true;
+                mPendingAnimationAction = START_ANIMATION;
                 return;
             }
 
@@ -1094,38 +1076,45 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
                 Log.d(LOGTAG, "Target is set. Starting VDAnimatorSet from java");
             }
 
-           nStart(mSetPtr, this);
+            mStarted = true;
+            nStart(mSetPtr, this, ++mLastListenerId);
             if (mListener != null) {
                 mListener.onAnimationStart(null);
             }
-            mStarted = true;
         }
 
         public void end() {
-            if (mInitialized && mStarted) {
+            if (mInitialized && useLastSeenTarget()) {
+                // If no target has ever been set, no-op
                 nEnd(mSetPtr);
-                onAnimationEnd();
             }
         }
 
-        void reset() {
-            if (!mInitialized) {
-                return;
+        public void reset() {
+            if (mInitialized && useLastSeenTarget()) {
+                // If no target has ever been set, no-op
+                nReset(mSetPtr);
             }
-            // TODO: Need to implement reset.
-            Log.w(LOGTAG, "Reset is yet to be implemented");
-            nReset(mSetPtr);
         }
 
         // Current (imperfect) Java AnimatorSet cannot be reversed when the set contains sequential
         // animators or when the animator set has a start delay
         void reverse() {
-            if (!mIsReversible) {
+            if (!mIsReversible || !mInitialized) {
+                return;
+            }
+            if (!useLastSeenTarget()) {
+                mPendingAnimationAction = REVERSE_ANIMATION;
                 return;
             }
-            // TODO: Need to support reverse (non-public API)
-            Log.w(LOGTAG, "Reverse is yet to be implemented");
-            nReverse(mSetPtr, this);
+            if (DBG_ANIMATION_VECTOR_DRAWABLE) {
+                Log.d(LOGTAG, "Target is set. Reversing VDAnimatorSet from java");
+            }
+            mStarted = true;
+            nReverse(mSetPtr, this, ++mLastListenerId);
+            if (mListener != null) {
+                mListener.onAnimationStart(null);
+            }
         }
 
         public long getAnimatorNativePtr() {
@@ -1155,7 +1144,13 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
             mListener = null;
         }
 
-        private void onAnimationEnd() {
+        private void onAnimationEnd(int listenerId) {
+            if (listenerId != mLastListenerId) {
+                return;
+            }
+            if (DBG_ANIMATION_VECTOR_DRAWABLE) {
+                Log.d(LOGTAG, "on finished called from native");
+            }
             mStarted = false;
             if (mListener != null) {
                 mListener.onAnimationEnd(null);
@@ -1164,11 +1159,8 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
         }
 
         // onFinished: should be called from native
-        private static void callOnFinished(VectorDrawableAnimator set) {
-            if (DBG_ANIMATION_VECTOR_DRAWABLE) {
-                Log.d(LOGTAG, "on finished called from native");
-            }
-            set.onAnimationEnd();
+        private static void callOnFinished(VectorDrawableAnimator set, int id) {
+            set.onAnimationEnd(id);
         }
     }
 
@@ -1188,8 +1180,8 @@ public class AnimatedVectorDrawable extends Drawable implements Animatable2 {
     private static native long nCreateRootAlphaPropertyHolder(long nativePtr, float startValue,
             float endValue);
     private static native void nSetPropertyHolderData(long nativePtr, float[] data, int length);
-    private static native void nStart(long animatorSetPtr, VectorDrawableAnimator set);
-    private static native void nReverse(long animatorSetPtr, VectorDrawableAnimator set);
+    private static native void nStart(long animatorSetPtr, VectorDrawableAnimator set, int id);
+    private static native void nReverse(long animatorSetPtr, VectorDrawableAnimator set, int id);
     private static native void nEnd(long animatorSetPtr);
     private static native void nReset(long animatorSetPtr);
 }
diff --git a/libs/hwui/Animator.cpp b/libs/hwui/Animator.cpp
index 7bd2b24bf56b..372bcb3b2375 100644
--- a/libs/hwui/Animator.cpp
+++ b/libs/hwui/Animator.cpp
@@ -42,7 +42,8 @@ BaseRenderNodeAnimator::BaseRenderNodeAnimator(float finalValue)
         , mStartTime(0)
         , mDuration(300)
         , mStartDelay(0)
-        , mMayRunAsync(true) {
+        , mMayRunAsync(true)
+        , mPlayTime(0) {
 }
 
 BaseRenderNodeAnimator::~BaseRenderNodeAnimator() {
@@ -85,20 +86,113 @@ void BaseRenderNodeAnimator::attach(RenderNode* target) {
     onAttached();
 }
 
+void BaseRenderNodeAnimator::start() {
+    mStagingPlayState = PlayState::Running;
+    mStagingRequests.push_back(Request::Start);
+    onStagingPlayStateChanged();
+}
+
+void BaseRenderNodeAnimator::cancel() {
+    mStagingPlayState = PlayState::Finished;
+    mStagingRequests.push_back(Request::Cancel);
+    onStagingPlayStateChanged();
+}
+
+void BaseRenderNodeAnimator::reset() {
+    mStagingPlayState = PlayState::Finished;
+    mStagingRequests.push_back(Request::Reset);
+    onStagingPlayStateChanged();
+}
+
+void BaseRenderNodeAnimator::reverse() {
+    mStagingPlayState = PlayState::Reversing;
+    mStagingRequests.push_back(Request::Reverse);
+    onStagingPlayStateChanged();
+}
+
+void BaseRenderNodeAnimator::end() {
+    mStagingPlayState = PlayState::Finished;
+    mStagingRequests.push_back(Request::End);
+    onStagingPlayStateChanged();
+}
+
+void BaseRenderNodeAnimator::resolveStagingRequest(Request request) {
+    switch (request) {
+    case Request::Start:
+        mPlayTime = (mPlayState == PlayState::Running || mPlayState == PlayState::Reversing) ?
+                        mPlayTime : 0;
+        mPlayState = PlayState::Running;
+        break;
+    case Request::Reverse:
+        mPlayTime = (mPlayState == PlayState::Running || mPlayState == PlayState::Reversing) ?
+                        mPlayTime : mDuration;
+        mPlayState = PlayState::Reversing;
+        break;
+    case Request::Reset:
+        mPlayTime = 0;
+        mPlayState = PlayState::Finished;
+        break;
+    case Request::Cancel:
+        mPlayState = PlayState::Finished;
+        break;
+    case Request::End:
+        mPlayTime = mPlayState == PlayState::Reversing ? 0 : mDuration;
+        mPlayState = PlayState::Finished;
+        break;
+    default:
+        LOG_ALWAYS_FATAL("Invalid staging request: %d", static_cast<int>(request));
+    };
+}
+
 void BaseRenderNodeAnimator::pushStaging(AnimationContext& context) {
     if (!mHasStartValue) {
         doSetStartValue(getValue(mTarget));
     }
-    if (mStagingPlayState > mPlayState) {
-        if (mStagingPlayState == PlayState::Restarted) {
-            mStagingPlayState = PlayState::Running;
+
+    if (!mStagingRequests.empty()) {
+        // Keep track of the play state and play time before they are changed when
+        // staging requests are resolved.
+        nsecs_t currentPlayTime = mPlayTime;
+        PlayState prevFramePlayState = mPlayState;
+
+        // Resolve staging requests one by one.
+        for (Request request : mStagingRequests) {
+            resolveStagingRequest(request);
         }
-        mPlayState = mStagingPlayState;
-        // Oh boy, we're starting! Man the battle stations!
-        if (mPlayState == PlayState::Running) {
-            transitionToRunning(context);
-        } else if (mPlayState == PlayState::Finished) {
+        mStagingRequests.clear();
+
+        if (mStagingPlayState == PlayState::Finished) {
+            // Set the staging play time and end the animation
+            updatePlayTime(mPlayTime);
             callOnFinishedListener(context);
+        } else if (mStagingPlayState == PlayState::Running
+                || mStagingPlayState == PlayState::Reversing) {
+            bool changed = currentPlayTime != mPlayTime || prevFramePlayState != mStagingPlayState;
+            if (prevFramePlayState != mStagingPlayState) {
+                transitionToRunning(context);
+            }
+            if (changed) {
+                // Now we need to seek to the stagingPlayTime (i.e. the animation progress that was
+                // requested from UI thread). It is achieved by modifying mStartTime, such that
+                // current time - mStartTime = stagingPlayTime (or mDuration -stagingPlayTime in the
+                // case of reversing)
+                nsecs_t currentFrameTime = context.frameTimeMs();
+                if (mPlayState == PlayState::Reversing) {
+                    // Reverse is not supported for animations with a start delay, so here we
+                    // assume no start delay.
+                    mStartTime = currentFrameTime  - (mDuration - mPlayTime);
+                } else {
+                    // Animation should play forward
+                    if (mPlayTime == 0) {
+                        // If the request is to start from the beginning, include start delay.
+                        mStartTime = currentFrameTime + mStartDelay;
+                    } else {
+                        // If the request is to seek to a non-zero play time, then we skip start
+                        // delay.
+                        mStartTime = currentFrameTime - mPlayTime;
+                    }
+                }
+            }
         }
     }
 }
@@ -136,37 +230,37 @@ bool BaseRenderNodeAnimator::animate(AnimationContext& context) {
 
     // This should be set before setValue() so animators can query this time when setValue
     // is called.
-    nsecs_t currentFrameTime = context.frameTimeMs();
-    onPlayTimeChanged(currentFrameTime - mStartTime);
+    nsecs_t currentPlayTime = context.frameTimeMs() - mStartTime;
+    bool finished = updatePlayTime(currentPlayTime);
+    if (finished && mPlayState != PlayState::Finished) {
+        mPlayState = PlayState::Finished;
+        callOnFinishedListener(context);
+    }
+    return finished;
+}
 
+bool BaseRenderNodeAnimator::updatePlayTime(nsecs_t playTime) {
+    mPlayTime = mPlayState == PlayState::Reversing ? mDuration - playTime : playTime;
+    onPlayTimeChanged(mPlayTime);
     // If BaseRenderNodeAnimator is handling the delay (not typical), then
     // because the staging properties reflect the final value, we always need
     // to call setValue even if the animation isn't yet running or is still
     // being delayed as we need to override the staging value
-    if (mStartTime > context.frameTimeMs()) {
+    if (playTime < 0) {
         setValue(mTarget, mFromValue);
         return false;
     }
 
     float fraction = 1.0f;
-
-    if (mPlayState == PlayState::Running && mDuration > 0) {
-        fraction = (float)(currentFrameTime - mStartTime) / mDuration;
-    }
-    if (fraction >= 1.0f) {
-        fraction = 1.0f;
-        mPlayState = PlayState::Finished;
+    if ((mPlayState == PlayState::Running || mPlayState == PlayState::Reversing) && mDuration > 0) {
+        fraction = mPlayTime / (float) mDuration;
     }
+    fraction = MathUtils::clamp(fraction, 0.0f, 1.0f);
 
     fraction = mInterpolator->interpolate(fraction);
     setValue(mTarget, mFromValue + (mDeltaValue * fraction));
 
-    if (mPlayState == PlayState::Finished) {
-        callOnFinishedListener(context);
-        return true;
-    }
-
-    return false;
+    return playTime >= mDuration;
 }
 
 void BaseRenderNodeAnimator::forceEndNow(AnimationContext& context) {
diff --git a/libs/hwui/Animator.h b/libs/hwui/Animator.h
index 2c9c9c3fe0f9..fcbc11b0306c 100644
--- a/libs/hwui/Animator.h
+++ b/libs/hwui/Animator.h
@@ -24,6 +24,8 @@
 
 #include "utils/Macros.h"
 
+#include <vector>
+
 namespace android {
 namespace uirenderer {
 
@@ -59,14 +61,14 @@ public:
         mMayRunAsync = mayRunAsync;
     }
     bool mayRunAsync() { return mMayRunAsync; }
-    ANDROID_API void start() {
-        if (mStagingPlayState == PlayState::NotStarted) {
-            mStagingPlayState = PlayState::Running;
-        } else {
-            mStagingPlayState = PlayState::Restarted;
-        }
-        onStagingPlayStateChanged(); }
-    ANDROID_API void end() { mStagingPlayState = PlayState::Finished; onStagingPlayStateChanged(); }
+    ANDROID_API void start();
+    ANDROID_API void reset();
+    ANDROID_API void reverse();
+    // Terminates the animation at its current progress.
+    ANDROID_API void cancel();
+
+    // Terminates the animation and skip to the end of the animation.
+    ANDROID_API void end();
 
     void attach(RenderNode* target);
     virtual void onAttached() {}
@@ -74,36 +76,41 @@ public:
     void pushStaging(AnimationContext& context);
     bool animate(AnimationContext& context);
 
-    bool isRunning() { return mPlayState == PlayState::Running; }
+    bool isRunning() { return mPlayState == PlayState::Running
+            || mPlayState == PlayState::Reversing; }
     bool isFinished() { return mPlayState == PlayState::Finished; }
     float finalValue() { return mFinalValue; }
 
     ANDROID_API virtual uint32_t dirtyMask() = 0;
 
     void forceEndNow(AnimationContext& context);
+    RenderNode* target() { return mTarget; }
 
 protected:
     // PlayState is used by mStagingPlayState and mPlayState to track the state initiated from UI
     // thread and Render Thread animation state, respectively.
     // From the UI thread, mStagingPlayState transition looks like
-    // NotStarted -> Running -> Finished
-    //                ^            |
-    //                |            |
-    //            Restarted <------
+    // NotStarted -> Running/Reversing -> Finished
+    //                ^                     |
+    //                |                     |
+    //                ----------------------
     // Note: For mStagingState, the Finished state (optional) is only set when the animation is
     // terminated by user.
     //
     // On Render Thread, mPlayState transition:
-    // NotStart -> Running -> Finished
-    //                ^            |
-    //                |            |
-    //                -------------
+    // NotStart -> Running/Reversing-> Finished
+    //                ^                 |
+    //                |                 |
+    //                ------------------
+    // Note that if the animation is in Running/Reversing state, calling start or reverse again
+    // would do nothing if the animation has the same play direction as the request; otherwise,
+    // the animation would start from where it is and change direction (i.e. Reversing <-> Running)
 
     enum class PlayState {
         NotStarted,
         Running,
+        Reversing,
         Finished,
-        Restarted,
     };
 
     BaseRenderNodeAnimator(float finalValue);
@@ -111,7 +118,6 @@ protected:
 
     virtual float getValue(RenderNode* target) const = 0;
     virtual void setValue(RenderNode* target, float value) = 0;
-    RenderNode* target() { return mTarget; }
 
     void callOnFinishedListener(AnimationContext& context);
 
@@ -132,13 +138,28 @@ protected:
     nsecs_t mDuration;
     nsecs_t mStartDelay;
     bool mMayRunAsync;
+    // Play Time tracks the progress of animation, it should always be [0, mDuration], 0 being
+    // the beginning of the animation, will reach mDuration at the end of an animation.
+    nsecs_t mPlayTime;
 
     sp<AnimationListener> mListener;
 
 private:
+    enum class Request {
+        Start,
+        Reverse,
+        Reset,
+        Cancel,
+        End
+    };
     inline void checkMutable();
     virtual void transitionToRunning(AnimationContext& context);
     void doSetStartValue(float value);
+    bool updatePlayTime(nsecs_t playTime);
+    void resolveStagingRequest(Request request);
+
+    std::vector<Request> mStagingRequests;
+
 };
 
 class RenderPropertyAnimator : public BaseRenderNodeAnimator {
diff --git a/libs/hwui/AnimatorManager.cpp b/libs/hwui/AnimatorManager.cpp
index cd30b1859384..2b49b4743d89 100644
--- a/libs/hwui/AnimatorManager.cpp
+++ b/libs/hwui/AnimatorManager.cpp
@@ -27,9 +27,8 @@ namespace uirenderer {
 
 using namespace std;
 
-static void unref(BaseRenderNodeAnimator* animator) {
+static void detach(sp<BaseRenderNodeAnimator>& animator) {
     animator->detach();
-    animator->decStrong(nullptr);
 }
 
 AnimatorManager::AnimatorManager(RenderNode& parent)
@@ -38,14 +37,12 @@ AnimatorManager::AnimatorManager(RenderNode& parent)
 }
 
 AnimatorManager::~AnimatorManager() {
-    for_each(mNewAnimators.begin(), mNewAnimators.end(), unref);
-    for_each(mAnimators.begin(), mAnimators.end(), unref);
+    for_each(mNewAnimators.begin(), mNewAnimators.end(), detach);
+    for_each(mAnimators.begin(), mAnimators.end(), detach);
 }
 
 void AnimatorManager::addAnimator(const sp<BaseRenderNodeAnimator>& animator) {
-    animator->incStrong(nullptr);
-    animator->attach(&mParent);
-    mNewAnimators.push_back(animator.get());
+    mNewAnimators.emplace_back(animator.get());
 }
 
 void AnimatorManager::setAnimationHandle(AnimationHandle* handle) {
@@ -56,25 +53,31 @@ void AnimatorManager::setAnimationHandle(AnimationHandle* handle) {
             &mParent, mParent.getName());
 }
 
-template<typename T>
-static void move_all(T& source, T& dest) {
-    dest.reserve(source.size() + dest.size());
-    for (typename T::iterator it = source.begin(); it != source.end(); it++) {
-        dest.push_back(*it);
-    }
-    source.clear();
-}
-
 void AnimatorManager::pushStaging() {
     if (mNewAnimators.size()) {
         LOG_ALWAYS_FATAL_IF(!mAnimationHandle,
                 "Trying to start new animators on %p (%s) without an animation handle!",
                 &mParent, mParent.getName());
-        // Since this is a straight move, we don't need to inc/dec the ref count
-        move_all(mNewAnimators, mAnimators);
+        // Only add animators that are not already in the on-going animator list.
+        for (auto& animator : mNewAnimators) {
+            RenderNode* targetRenderNode = animator->target();
+            if (targetRenderNode == &mParent) {
+                // Animator already in the animator list: skip adding again
+                continue;
+            }
+
+            if (targetRenderNode){
+                // If the animator is already in another RenderNode's animator list, remove animator from
+                // that list and add animator to current RenderNode's list.
+                targetRenderNode->animators().removeActiveAnimator(animator);
+            }
+            animator->attach(&mParent);
+            mAnimators.push_back(std::move(animator));
+        }
+        mNewAnimators.clear();
     }
-    for (vector<BaseRenderNodeAnimator*>::iterator it = mAnimators.begin(); it != mAnimators.end(); it++) {
-        (*it)->pushStaging(mAnimationHandle->context());
+    for (auto& animator : mAnimators) {
+        animator->pushStaging(mAnimationHandle->context());
     }
 }
 
@@ -83,11 +86,11 @@ public:
     AnimateFunctor(TreeInfo& info, AnimationContext& context)
             : dirtyMask(0), mInfo(info), mContext(context) {}
 
-    bool operator() (BaseRenderNodeAnimator* animator) {
+    bool operator() (sp<BaseRenderNodeAnimator>& animator) {
         dirtyMask |= animator->dirtyMask();
         bool remove = animator->animate(mContext);
         if (remove) {
-            animator->decStrong(nullptr);
+            animator->detach();
         } else {
             if (animator->isRunning()) {
                 mInfo.out.hasAnimations = true;
@@ -129,20 +132,18 @@ void AnimatorManager::animateNoDamage(TreeInfo& info) {
 
 uint32_t AnimatorManager::animateCommon(TreeInfo& info) {
     AnimateFunctor functor(info, mAnimationHandle->context());
-    std::vector< BaseRenderNodeAnimator* >::iterator newEnd;
-    newEnd = std::remove_if(mAnimators.begin(), mAnimators.end(), functor);
+    auto newEnd = std::remove_if(mAnimators.begin(), mAnimators.end(), functor);
     mAnimators.erase(newEnd, mAnimators.end());
     mAnimationHandle->notifyAnimationsRan();
     mParent.mProperties.updateMatrix();
     return functor.dirtyMask;
 }
 
-static void endStagingAnimator(BaseRenderNodeAnimator* animator) {
-    animator->end();
+static void endStagingAnimator(sp<BaseRenderNodeAnimator>& animator) {
+    animator->cancel();
     if (animator->listener()) {
-        animator->listener()->onAnimationFinished(animator);
+        animator->listener()->onAnimationFinished(animator.get());
     }
-    animator->decStrong(nullptr);
 }
 
 void AnimatorManager::endAllStagingAnimators() {
@@ -153,13 +154,16 @@ void AnimatorManager::endAllStagingAnimators() {
     mNewAnimators.clear();
 }
 
+void AnimatorManager::removeActiveAnimator(const sp<BaseRenderNodeAnimator>& animator) {
+    std::remove(mAnimators.begin(), mAnimators.end(), animator);
+}
+
 class EndActiveAnimatorsFunctor {
 public:
     EndActiveAnimatorsFunctor(AnimationContext& context) : mContext(context) {}
 
-    void operator() (BaseRenderNodeAnimator* animator) {
+    void operator() (sp<BaseRenderNodeAnimator>& animator) {
         animator->forceEndNow(mContext);
-        animator->decStrong(nullptr);
     }
 
 private:
diff --git a/libs/hwui/AnimatorManager.h b/libs/hwui/AnimatorManager.h
index fb75eb8599b4..c24ef47a4644 100644
--- a/libs/hwui/AnimatorManager.h
+++ b/libs/hwui/AnimatorManager.h
@@ -62,13 +62,17 @@ public:
 private:
     uint32_t animateCommon(TreeInfo& info);
 
+    // This would remove the animator from mAnimators list. It should only be called during
+    // push staging.
+    void removeActiveAnimator(const sp<BaseRenderNodeAnimator>& animator);
+
     RenderNode& mParent;
     AnimationHandle* mAnimationHandle;
 
     // To improve the efficiency of resizing & removing from the vector
     // use manual ref counting instead of sp<>.
-    std::vector<BaseRenderNodeAnimator*> mNewAnimators;
-    std::vector<BaseRenderNodeAnimator*> mAnimators;
+    std::vector< sp<BaseRenderNodeAnimator> > mNewAnimators;
+    std::vector< sp<BaseRenderNodeAnimator> > mAnimators;
 };
 
 } /* namespace uirenderer */
diff --git a/libs/hwui/PropertyValuesAnimatorSet.cpp b/libs/hwui/PropertyValuesAnimatorSet.cpp
index eca1afcc54dc..b29f91ff34aa 100644
--- a/libs/hwui/PropertyValuesAnimatorSet.cpp
+++ b/libs/hwui/PropertyValuesAnimatorSet.cpp
@@ -17,6 +17,8 @@
 #include "PropertyValuesAnimatorSet.h"
 #include "RenderNode.h"
 
+#include <algorithm>
+
 namespace android {
 namespace uirenderer {
 
@@ -53,16 +55,26 @@ void PropertyValuesAnimatorSet::setValue(RenderNode* target, float value) {
 }
 
 void PropertyValuesAnimatorSet::onPlayTimeChanged(nsecs_t playTime) {
-    for (size_t i = 0; i < mAnimators.size(); i++) {
-        mAnimators[i]->setCurrentPlayTime(playTime);
+    if (playTime == 0 && mDuration > 0) {
+        // Reset all the animators
+        for (auto it = mAnimators.rbegin(); it != mAnimators.rend(); it++) {
+            // Note that this set may containing animators modifying the same property, so when we
+            // reset the animators, we need to make sure the animators that end the first will
+            // have the final say on what the property value should be.
+            (*it)->setFraction(0);
+        }
+    } else if (playTime >= mDuration) {
+        // Skip all the animators to end
+        for (auto& anim : mAnimators) {
+            anim->setFraction(1);
+        }
+    } else {
+        for (auto& anim : mAnimators) {
+            anim->setCurrentPlayTime(playTime);
+        }
     }
 }
 
-void PropertyValuesAnimatorSet::reset() {
-    // TODO: implement reset through adding a play state because we need to support reset() even
-    // during an animation run.
-}
-
 void PropertyValuesAnimatorSet::start(AnimationListener* listener) {
     init();
     mOneShotListener = listener;
@@ -70,20 +82,23 @@ void PropertyValuesAnimatorSet::start(AnimationListener* listener) {
 }
 
 void PropertyValuesAnimatorSet::reverse(AnimationListener* listener) {
-// TODO: implement reverse
+    init();
+    mOneShotListener = listener;
+    BaseRenderNodeAnimator::reverse();
 }
 
 void PropertyValuesAnimatorSet::init() {
     if (mInitialized) {
         return;
     }
-    nsecs_t maxDuration = 0;
-    for (size_t i = 0; i < mAnimators.size(); i++) {
-        if (maxDuration < mAnimators[i]->getTotalDuration()) {
-            maxDuration = mAnimators[i]->getTotalDuration();
-        }
-    }
-    mDuration = maxDuration;
+
+    // Sort the animators by their total duration. Note that all the animators in the set start at
+    // the same time, so the ones with longer total duration (which includes start delay) will
+    // be the ones that end later.
+    std::sort(mAnimators.begin(), mAnimators.end(), [](auto& a, auto&b) {
+        return a->getTotalDuration() < b->getTotalDuration();
+    });
+    mDuration = mAnimators[mAnimators.size() - 1]->getTotalDuration();
     mInitialized = true;
 }
 
@@ -106,18 +121,19 @@ PropertyAnimator::PropertyAnimator(PropertyValuesHolder* holder, Interpolator* i
 void PropertyAnimator::setCurrentPlayTime(nsecs_t playTime) {
     if (playTime >= mStartDelay && playTime < mTotalDuration) {
          nsecs_t currentIterationPlayTime = (playTime - mStartDelay) % mDuration;
-         mLatestFraction = currentIterationPlayTime / (float) mDuration;
+         float fraction = currentIterationPlayTime / (float) mDuration;
+         setFraction(fraction);
     } else if (mLatestFraction < 1.0f && playTime >= mTotalDuration) {
-        mLatestFraction = 1.0f;
-    } else {
-        return;
+        // This makes sure we only set the fraction = 1 once. It is needed because there might
+        // be another animator modifying the same property after this animator finishes, we need
+        // to make sure we don't set conflicting values on the same property within one frame.
+        setFraction(1.0f);
     }
-
-    setFraction(mLatestFraction);
 }
 
 void PropertyAnimator::setFraction(float fraction) {
-    float interpolatedFraction = mInterpolator->interpolate(mLatestFraction);
+    mLatestFraction = fraction;
+    float interpolatedFraction = mInterpolator->interpolate(fraction);
     mPropertyValuesHolder->setFraction(interpolatedFraction);
 }
 
diff --git a/libs/hwui/PropertyValuesAnimatorSet.h b/libs/hwui/PropertyValuesAnimatorSet.h
index 4c7ce528bb20..c7ae7c0e8ce1 100644
--- a/libs/hwui/PropertyValuesAnimatorSet.h
+++ b/libs/hwui/PropertyValuesAnimatorSet.h
@@ -50,7 +50,6 @@ public:
 
     void start(AnimationListener* listener);
     void reverse(AnimationListener* listener);
-    void reset();
 
     void addPropertyAnimator(PropertyValuesHolder* propertyValuesHolder,
             Interpolator* interpolators, int64_t startDelays,