Property Animation
在AnimationHandler中的循环取帧的关键代码：
private final Choreographer.FrameCallback mFrameCallback = new Choreographer.FrameCallback() {
@Override
public void doFrame(long frameTimeNanos) {
doAnimationFrame(getProvider().getFrameTime());
if (mAnimationCallbacks.size() > 0) {
getProvider().postFrameCallback(this);
}
}
};
View Animation
在ViewRootImpl中的关键代码：
void scheduleTraversals() {
...
mChoreographer.postCallback(
Choreographer.CALLBACK_TRAVERSAL, mTraversalRunnable, null);
...
}
Drawable Animation
在View中的关键代码：
@Override
public void scheduleDrawable(@NonNull Drawable who, @NonNull Runnable what, long when) {
if (verifyDrawable(who) && what != null) {
final long delay = when - SystemClock.uptimeMillis();
if (mAttachInfo != null) {
mAttachInfo.mViewRootImpl.mChoreographer.postCallbackDelayed(
Choreographer.CALLBACK_ANIMATION, what, who,
Choreographer.subtractFrameDelay(delay));
} else {
// Postpone the runnable until we know
// on which thread it needs to run.
getRunQueue().postDelayed(what, delay);
}
}
}
