Android Animation调整LinearLayout的高度

Question

I have 2 LinearLayouts with views within them held in a container LinearLayout that is using layout_weight to determine their sizes. I am trying to shrink the top view when the user clicks inside the bottom view with an animation.

I extended Animation with a class:

public class ShrinkTopViewAnimation extends Animation {

    protected int mOriginalHeight;
    protected final LinearLayout mView;

    public ShrinkTopViewAnimation(LinearLayout view) {
        this.mView = view;
    }

    @Override
    public void initialize(int width, int height, int parentWidth, int parentHeight) {
        super.initialize(width, height, parentWidth, parentHeight);
        mOriginalHeight = height;
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation transformation
    ) {
        int shrinkAmount = (int)(mOriginalHeight * interpolatedTime);
        ViewGroup.LayoutParams layoutParams = mView.getLayoutParams();
        layoutParams.height = mOriginalHeight - shrinkAmount;
        mView.setLayoutParams(layoutParams);
        mView.requestLayout();
    }

    @Override
    public boolean willChangeBounds() {
        return true;
    }
}

The BottomView onClick calls:

        ShrinkTopViewAnimation shrinkTopViewAnimation = new ShrinkTopViewAnimation(mTopLinearLayout);
        shrinkTopViewAnimation.setDuration(1000);
        mTopLinearLayout.startAnimation(shrinkTopViewAnimation);

I am very confused as to what is happening. What I am seeing is that the first time through the applyTransform the interpolatedTime is 0 so the .height is set to the exact same number that it was before. But the next call to the applyTransformation a getHeight call to the mView gives a number way bigger than the starting height and at the end of the transform when interpolatedTime is 1 the view is back to the original size. The visual effect is the top view jumps larger, then shrinks back to original size.

Both getHeight() and the initialize Height are listed as px in the documentation, and the LayoutParams.Height is listed as px. But it seems like there is some translation to dp possibly going on?

Any ideas?

Answer 1

To keep the animated result, use Animation.setFillAfter(true) .

When set to true, the animation transformation is applied after the animation is over.

What you used here is View Animation . This kind of animation only modify rendering transformation, so the actual size of view is not changed.

If you need to changed the actual size, you have to set LayoutParams via a AnimationListener , or use a Property Animation .