/**
* Sets the position of the animation to the specified point in time. This time should be between
* 0 and the total duration of the animation, including any repetition. If the animation has not
* yet been started, then it will not advance forward after it is set to this time; it will simply
* set the time to this value and perform any appropriate actions based on that time. If the
* animation is already running, then setCurrentPlayTime() will set the current playing time to
* this value and continue playing from that point.
*
* @param playTime The time, in milliseconds, to which the animation is advanced or rewound.
*/
public void setCurrentPlayTime(long playTime) {
initAnimation();
long currentTime = AnimationUtils.currentAnimationTimeMillis();
if (mPlayingState != RUNNING) {
mSeekTime = playTime;
mPlayingState = SEEKED;
}
mStartTime = currentTime - playTime;
animationFrame(currentTime);
}
/**
* There are only two messages that we care about: ANIMATION_START and ANIMATION_FRAME. The
* START message is sent when an animation's start() method is called. It cannot start
* synchronously when start() is called because the call may be on the wrong thread, and it
* would also not be synchronized with other animations because it would not start on a common
* timing pulse. So each animation sends a START message to the handler, which causes the
* handler to place the animation on the active animations queue and start processing frames for
* that animation. The FRAME message is the one that is sent over and over while there are any
* active animations to process.
*/
public void handleMessage(Message msg) {
boolean callAgain = true;
ArrayList<ValueAnimator> animations = sAnimations.get();
ArrayList<ValueAnimator> delayedAnims = sDelayedAnims.get();
switch (msg.what) {
// TODO: should we avoid sending frame message when starting if we
// were already running?
case ANIMATION_START:
ArrayList<ValueAnimator> pendingAnimations = sPendingAnimations.get();
if (animations.size() > 0 || delayedAnims.size() > 0) {
callAgain = false;
}
// pendingAnims holds any animations that have requested to be started
// We're going to clear sPendingAnimations, but starting animation may
// cause more to be added to the pending list (for example, if one animation
// starting triggers another starting). So we loop until sPendingAnimations
// is empty.
while (pendingAnimations.size() > 0) {
ArrayList<ValueAnimator> pendingCopy =
(ArrayList<ValueAnimator>) pendingAnimations.clone();
pendingAnimations.clear();
int count = pendingCopy.size();
for (int i = 0; i < count; ++i) {
ValueAnimator anim = pendingCopy.get(i);
// If the animation has a startDelay, place it on the delayed list
if (anim.mStartDelay == 0) {
anim.startAnimation();
} else {
delayedAnims.add(anim);
}
}
}
// fall through to process first frame of new animations
case ANIMATION_FRAME:
// currentTime holds the common time for all animations processed
// during this frame
long currentTime = AnimationUtils.currentAnimationTimeMillis();
ArrayList<ValueAnimator> readyAnims = sReadyAnims.get();
ArrayList<ValueAnimator> endingAnims = sEndingAnims.get();
// First, process animations currently sitting on the delayed queue, adding
// them to the active animations if they are ready
int numDelayedAnims = delayedAnims.size();
for (int i = 0; i < numDelayedAnims; ++i) {
ValueAnimator anim = delayedAnims.get(i);
if (anim.delayedAnimationFrame(currentTime)) {
readyAnims.add(anim);
}
}
int numReadyAnims = readyAnims.size();
if (numReadyAnims > 0) {
for (int i = 0; i < numReadyAnims; ++i) {
ValueAnimator anim = readyAnims.get(i);
anim.startAnimation();
anim.mRunning = true;
delayedAnims.remove(anim);
}
readyAnims.clear();
}
// Now process all active animations. The return value from animationFrame()
// tells the handler whether it should now be ended
int numAnims = animations.size();
int i = 0;
while (i < numAnims) {
ValueAnimator anim = animations.get(i);
if (anim.animationFrame(currentTime)) {
endingAnims.add(anim);
}
if (animations.size() == numAnims) {
++i;
} else {
// An animation might be canceled or ended by client code
// during the animation frame. Check to see if this happened by
// seeing whether the current index is the same as it was before
// calling animationFrame(). Another approach would be to copy
// animations to a temporary list and process that list instead,
// but that entails garbage and processing overhead that would
// be nice to avoid.
--numAnims;
endingAnims.remove(anim);
}
}
if (endingAnims.size() > 0) {
for (i = 0; i < endingAnims.size(); ++i) {
endingAnims.get(i).endAnimation();
}
endingAnims.clear();
}
// If there are still active or delayed animations, call the handler again
// after the frameDelay
if (callAgain && (!animations.isEmpty() || !delayedAnims.isEmpty())) {
sendEmptyMessageDelayed(
ANIMATION_FRAME,
Math.max(
0, sFrameDelay - (AnimationUtils.currentAnimationTimeMillis() - currentTime)));
}
break;
}
}