Interrupt translate animation and start another

Question

I have an application where I need to adjust view position according to current focused subview (it's a list with focusable items, current focused item must be in the center of the screen - used for a tv application controlled from tv remote).
Position must be adjusted with animation.
I got it working with just one problem: if the user changes focus before the animation is complete (quickly taps "up" button twice) next animation starts with "jump" - it starts from the same position as did the first one.

So what I try to do is I cancel previous animation and start another, but then new animation starts from the point where first animation was started, so user can see a very obvious jumps in the animation, which look really awful.

Here's the code:

@Override
public void requestChildFocus(final View child, final View focused) {
    super.requestChildFocus(child, focused);

    //this test code included for explanation
    Rect r = new Rect();
    child.getDrawingRect(r); //this will return view's position ignoring animation state
    Rect r2 = new Rect();
    child.getGlobalVisibleRect(r2); //as will this one too
    Log.d("Top: " + child.getTop() + "; Drawing rect: " +  r.toString() + "; global visible rect: " + r2.toString()); 
    //all of this methods will ignore changes that were made 
    //by animation object - they'll return numbers from LayoutParam

    //calculate current position inside view and position to move to
    //cursorOffset - is the "center" of the screen
    final int currentPosition = child.getTop();
    final int requaredPosition = cursorOffset - focused.getTop();

    //cancel current running animation - layout params will not change
    //if i do change layout params when cancelling animation, it looks even worse
    //because of jumping back list jumps forward
    if (currentAnimation != null) {
        Animation animation = currentAnimation;
        currentAnimation = null;
        animation.cancel();
    }

    //just a regular translate animation
    TranslateAnimation animation = new TranslateAnimation(0, 0, 0, requaredPosition - currentPosition);
    animation.setDuration(300);
    animation.setFillEnabled(true);
    animation.setFillBefore(true);
    animation.setAnimationListener(new AnimationListener() {

        @Override
        public void onAnimationStart(Animation animation) {
            currentAnimation = animation;
        }

        @Override
        public void onAnimationRepeat(Animation animation) {}

        @Override
        public void onAnimationEnd(Animation animation) {
            if (animation == currentAnimation) {
                //change layout params if animation finished running (wasn't cancelled)
                RelativeLayout.LayoutParams params = (LayoutParams) child.getLayoutParams();
                params.setMargins(0, requaredPosition, 0, 0);
                child.setLayoutParams(params);
            }
        }
    });
    child.startAnimation(animation);
}

So must question is: how can I start translate animation from the point where previous translate animation left on (assuming that it was cancelled)?
Or, in a simplier words, how can I determine current visible rect of a view?

Answer 1

Apparently you can't get current view position, but you can get current animation state.
So you can get current y offset by doing this:

Transformation transformation = new Transformation();
float[] matrix = new float[9];
currentAnimation.getTransformation(AnimationUtils.currentAnimationTimeMillis(), transformation);
transformation.getMatrix().getValues(matrix);
float y = matrix[Matrix.MTRANS_Y];

And that's how I was able to cancel one animation and start another one exactly from the point where I left of. If anyone cares, heres the complete code:

private Animation currentAnimation;
private float[] matrix = new float[9];
private Transformation transformation = new Transformation();

@Override
public void requestChildFocus(final View child, final View focused) {
    super.requestChildFocus(child, focused);

    final int currentPosition;

    if (currentAnimation != null) {
        currentAnimation.getTransformation(AnimationUtils.currentAnimationTimeMillis(), transformation);
        transformation.getMatrix().getValues(matrix);
        float y = matrix[Matrix.MTRANS_Y];

        RelativeLayout.LayoutParams params = (LayoutParams) child.getLayoutParams();
        params.topMargin += y;
        //child.getTop() will return wrong position until layout actually happens, 
        //so I use params.topMargin as a current position in case I need to cancel
        currentPosition = params.topMargin;
        child.requestLayout();

        currentAnimation.setAnimationListener(null);
        currentAnimation.cancel();
        currentAnimation = null;
    } else {
        currentPosition = child.getTop();
    }

    final int requaredPosition = cursorOffset - focused.getTop();

    TranslateAnimation animation = new TranslateAnimation(0, 0, 0, requaredPosition - currentPosition);
    animation.setDuration(300);
    animation.setFillEnabled(true);
    animation.setFillBefore(true);
    animation.setAnimationListener(new AnimationListener() {

        @Override
        public void onAnimationStart(Animation animation) {
            currentAnimation = animation;
        }

        @Override
        public void onAnimationRepeat(Animation animation) {}

        @Override
        public void onAnimationEnd(Animation animation) {
            if (animation == currentAnimation) {
                RelativeLayout.LayoutParams params = (LayoutParams) child.getLayoutParams();
                params.setMargins(0, requaredPosition, 0, 0);
                child.requestLayout();
            }
            currentAnimation = null;
        }
    });
    child.startAnimation(animation);
}

Hope somebody finds this useful.

Answer 2

For everybody that searches for help to create a clock or a speedometer like me (look for RotationAnimation < API lvl 9), I found out, that it is a good idea to set the AnimationListener and save the animation state in a boolean variable. Before you start a new animation check the state. So your animation will run until the end and look very smoothly. I am sorry for my english.

        if(isAnimationActive){
        //[...]
        rotate = new RotateAnimation(oldRotateDegree, rotateDegree, Animation.RELATIVE_TO_SELF, 0.5f,
                            Animation.RELATIVE_TO_SELF, 0.5f);
                    rotate.setDuration(rotateDuration);
                    rotate.setFillAfter(true);
                    rotate.setAnimationListener(this);
       }        
       //[...]

        @Override
        public void onAnimationEnd(Animation animation)
        {
            this.isAnimationActive = false;

        }
        @Override
        public void onAnimationStart(Animation animation)
        {
            this.isAnimationActive = true;  
        }