Change position of view after end of animation

问题:

I develop a widget based on ViewGroup and my problem is that I need to save position of items after the end of animation. I called setFillAfter(true) in my animation object I created AnimationListener and in it's onAnimationEnd method call View.layout(l,t,r,b) to set the position after animation, because I want animation to start from new item's position next time. But in this case it looks like items are layouted twice. If I don't use View.layout(l,t,r,b) at the end of animation, next animation starts from previous position. Here is my code:

private void scrollUp() {
    for(int i = 0; i < getChildCount(); i++) {
        final View child = getChildAt(i);
        final int index = i; 
        final int newleft = child.getLeft() + mOffsetBetweenItems;
        final int newTop = child.getTop() - mOffsetBetweenItems;
        TranslateAnimation scrollUp = new TranslateAnimation(0, mOffsetBetweenItems, 0, -mOffsetBetweenItems);          
        scrollUp.setDuration(1500);
        scrollUp.setFillAfter(true);        
        scrollUp.setAnimationListener(
            new AnimationListener() {

                @Override
                public void onAnimationStart(Animation animation) {}

                @Override
                public void onAnimationRepeat(Animation animation) {}

                @Override
                public void onAnimationEnd(Animation animation) {
                    child.layout(newleft, newTop, newleft + child.getMeasuredWidth(), newTop + child.getMeasuredHeight() );
                }
            }
        );

        child.startAnimation(scrollUp);
    }
}

Please give me an advice how should I reset view's position accordingly to the end position of animation?

回答1:

You must use ObjectAnimator , it works from API 11 level . It changes View position automatic,

here is the example

ObjectAnimator objectAnimator= ObjectAnimator.ofFloat(mContent_container, "translationX", startX, endX);
objectAnimator.setDuration(1000);
objectAnimator.start();

Thanks JUL for his answer

If your app not found object animator, change the API level from Project -> properties -> Android , than import android.animation.ObjectAnimator;

回答2:

I did it. Here is the code:

private void scrollUp() {
    for(int i = 0; i < getChildCount(); i++) {
        final View child = getChildAt(i);
        final int index = i; 
        final int newleft = child.getLeft() + mOffsetBetweenItems;
        final int newTop = child.getTop() - mOffsetBetweenItems;
        TranslateAnimation scrollUp = new TranslateAnimation(0, mOffsetBetweenItems, 0, -mOffsetBetweenItems);          
        scrollUp.setDuration(1500);
        scrollUp.setFillEnabled(true);        
        scrollUp.setAnimationListener(
            new AnimationListener() {

                @Override
                public void onAnimationStart(Animation animation) {}

                @Override
                public void onAnimationRepeat(Animation animation) {}

                @Override
                public void onAnimationEnd(Animation animation) {
                    child.layout(newleft, newTop, newleft + child.getMeasuredWidth(), newTop + child.getMeasuredHeight() );
                }
            }
        );

        child.startAnimation(scrollUp);
    }
}

Just removed setFillAfter(true) and write setFillEnabled(true) instead of. But in this case I don't understand the logic of setFillEnabled() working, because it provides behavior not like describes in documentation.

回答3:

Reverse your animation; Start by giving your view a new position and then animate from the old position to the new position.