/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.animation;
import android.os.SystemClock;
import android.util.ArrayMap;
import android.view.Choreographer;
import java.util.ArrayList;
/**
* This custom, static handler handles the timing pulse that is shared by all active
* ValueAnimators. This approach ensures that the setting of animation values will happen on the
* same thread that animations start on, and that all animations will share the same times for
* calculating their values, which makes synchronizing animations possible.
*
* The handler uses the Choreographer by default for doing periodic callbacks. A custom
* AnimationFrameCallbackProvider can be set on the handler to provide timing pulse that
* may be independent of UI frame update. This could be useful in testing.
*
* @hide
*/
public class AnimationHandler {
/**
* Internal per-thread collections used to avoid set collisions as animations start and end
* while being processed.
* @hide
*/
private final ArrayMap<AnimationFrameCallback, Long> mDelayedCallbackStartTime =
new ArrayMap<>();
private final ArrayList<AnimationFrameCallback> mAnimationCallbacks =
new ArrayList<>();
private final ArrayList<AnimationFrameCallback> mCommitCallbacks =
new ArrayList<>();
private AnimationFrameCallbackProvider mProvider;
private final Choreographer.FrameCallback mFrameCallback = new Choreographer.FrameCallback() {
@Override
public void doFrame(long frameTimeNanos) {
doAnimationFrame(getProvider().getFrameTime());
if (mAnimationCallbacks.size() > 0) {
getProvider().postFrameCallback(this);
}
}
};
public final static ThreadLocal<AnimationHandler> sAnimatorHandler = new ThreadLocal<>();
private boolean mListDirty = false;
public static AnimationHandler getInstance() {
if (sAnimatorHandler.get() == null) {
sAnimatorHandler.set(new AnimationHandler());
}
return sAnimatorHandler.get();
}
/**
* By default, the Choreographer is used to provide timing for frame callbacks. A custom
* provider can be used here to provide different timing pulse.
*/
public void setProvider(AnimationFrameCallbackProvider provider) {
if (provider == null) {
mProvider = new MyFrameCallbackProvider();
} else {
mProvider = provider;
}
}
private AnimationFrameCallbackProvider getProvider() {
if (mProvider == null) {
mProvider = new MyFrameCallbackProvider();
}
return mProvider;
}
/**
* Register to get a callback on the next frame after the delay.
*/
public void addAnimationFrameCallback(final AnimationFrameCallback callback, long delay) {
if (mAnimationCallbacks.size() == 0) {
getProvider().postFrameCallback(mFrameCallback);
}
if (!mAnimationCallbacks.contains(callback)) {
mAnimationCallbacks.add(callback);
}
if (delay > 0) {
mDelayedCallbackStartTime.put(callback, (SystemClock.uptimeMillis() + delay));
}
}
/**
* Register to get a one shot callback for frame commit timing. Frame commit timing is the
* time *after* traversals are done, as opposed to the animation frame timing, which is
* before any traversals. This timing can be used to adjust the start time of an animation
* when expensive traversals create big delta between the animation frame timing and the time
* that animation is first shown on screen.
*
* Note this should only be called when the animation has already registered to receive
* animation frame callbacks. This callback will be guaranteed to happen *after* the next
* animation frame callback.
*/
public void addOneShotCommitCallback(final AnimationFrameCallback callback) {
if (!mCommitCallbacks.contains(callback)) {
mCommitCallbacks.add(callback);
}
}
/**
* Removes the given callback from the list, so it will no longer be called for frame related
* timing.
*/
public void removeCallback(AnimationFrameCallback callback) {
mCommitCallbacks.remove(callback);
mDelayedCallbackStartTime.remove(callback);
int id = mAnimationCallbacks.indexOf(callback);
if (id >= 0) {
mAnimationCallbacks.set(id, null);
mListDirty = true;
}
}
private void doAnimationFrame(long frameTime) {
int size = mAnimationCallbacks.size();
long currentTime = SystemClock.uptimeMillis();
for (int i = 0; i < size; i++) {
final AnimationFrameCallback callback = mAnimationCallbacks.get(i);
if (callback == null) {
continue;
}
if (isCallbackDue(callback, currentTime)) {
callback.doAnimationFrame(frameTime);
if (mCommitCallbacks.contains(callback)) {
getProvider().postCommitCallback(new Runnable() {
@Override
public void run() {
commitAnimationFrame(callback, getProvider().getFrameTime());
}
});
}
}
}
cleanUpList();
}
private void commitAnimationFrame(AnimationFrameCallback callback, long frameTime) {
if (!mDelayedCallbackStartTime.containsKey(callback) &&
mCommitCallbacks.contains(callback)) {
callback.commitAnimationFrame(frameTime);
mCommitCallbacks.remove(callback);
}
}
/**
* Remove the callbacks from mDelayedCallbackStartTime once they have passed the initial delay
* so that they can start getting frame callbacks.
*
* @return true if they have passed the initial delay or have no delay, false otherwise.
*/
private boolean isCallbackDue(AnimationFrameCallback callback, long currentTime) {
Long startTime = mDelayedCallbackStartTime.get(callback);
if (startTime == null) {
return true;
}
if (startTime < currentTime) {
mDelayedCallbackStartTime.remove(callback);
return true;
}
return false;
}
/**
* Return the number of callbacks that have registered for frame callbacks.
*/
public static int getAnimationCount() {
AnimationHandler handler = sAnimatorHandler.get();
if (handler == null) {
return 0;
}
return handler.getCallbackSize();
}
public static void setFrameDelay(long delay) {
getInstance().getProvider().setFrameDelay(delay);
}
public static long getFrameDelay() {
return getInstance().getProvider().getFrameDelay();
}
void autoCancelBasedOn(ObjectAnimator objectAnimator) {
for (int i = mAnimationCallbacks.size() - 1; i >= 0; i--) {
AnimationFrameCallback cb = mAnimationCallbacks.get(i);
if (cb == null) {
continue;
}
if (objectAnimator.shouldAutoCancel(cb)) {
((Animator) mAnimationCallbacks.get(i)).cancel();
}
}
}
private void cleanUpList() {
if (mListDirty) {
for (int i = mAnimationCallbacks.size() - 1; i >= 0; i--) {
if (mAnimationCallbacks.get(i) == null) {
mAnimationCallbacks.remove(i);
}
}
mListDirty = false;
}
}
private int getCallbackSize() {
int count = 0;
int size = mAnimationCallbacks.size();
for (int i = size - 1; i >= 0; i--) {
if (mAnimationCallbacks.get(i) != null) {
count++;
}
}
return count;
}
/**
* Default provider of timing pulse that uses Choreographer for frame callbacks.
*/
private class MyFrameCallbackProvider implements AnimationFrameCallbackProvider {
final Choreographer mChoreographer = Choreographer.getInstance();
@Override
public void postFrameCallback(Choreographer.FrameCallback callback) {
mChoreographer.postFrameCallback(callback);
}
@Override
public void postCommitCallback(Runnable runnable) {
mChoreographer.postCallback(Choreographer.CALLBACK_COMMIT, runnable, null);
}
@Override
public long getFrameTime() {
return mChoreographer.getFrameTime();
}
@Override
public long getFrameDelay() {
return Choreographer.getFrameDelay();
}
@Override
public void setFrameDelay(long delay) {
Choreographer.setFrameDelay(delay);
}
}
/**
* Callbacks that receives notifications for animation timing and frame commit timing.
*/
interface AnimationFrameCallback {
/**
* Run animation based on the frame time.
* @param frameTime The frame start time, in the {@link SystemClock#uptimeMillis()} time
* base.
*/
void doAnimationFrame(long frameTime);
/**
* This notifies the callback of frame commit time. Frame commit time is the time after
* traversals happen, as opposed to the normal animation frame time that is before
* traversals. This is used to compensate expensive traversals that happen as the
* animation starts. When traversals take a long time to complete, the rendering of the
* initial frame will be delayed (by a long time). But since the startTime of the
* animation is set before the traversal, by the time of next frame, a lot of time would
* have passed since startTime was set, the animation will consequently skip a few frames
* to respect the new frameTime. By having the commit time, we can adjust the start time to
* when the first frame was drawn (after any expensive traversals) so that no frames
* will be skipped.
*
* @param frameTime The frame time after traversals happen, if any, in the
* {@link SystemClock#uptimeMillis()} time base.
*/
void commitAnimationFrame(long frameTime);
}
/**
* The intention for having this interface is to increase the testability of ValueAnimator.
* Specifically, we can have a custom implementation of the interface below and provide
* timing pulse without using Choreographer. That way we could use any arbitrary interval for
* our timing pulse in the tests.
*
* @hide
*/
public interface AnimationFrameCallbackProvider {
void postFrameCallback(Choreographer.FrameCallback callback);
void postCommitCallback(Runnable runnable);
long getFrameTime();
long getFrameDelay();
void setFrameDelay(long delay);
}
}