android - How to expand a layout height with animation?

Question

I couldn't find a good example for how to do this.

I have a RelativeLayout set with x height.

I want to add a button which expands the height to x+y height.

can someone refer me to a good example on how to do it programmatically?

Answer 1

You marked the solution that was closest. This is the exact solution. I had the same problem. Hopefully this answer will help others.

InstantiateResizeAnimation

ResizeAnimation resizeAnimation = new ResizeAnimation(
     view, 
     targetHeight, 
     startHeight
); 
resizeAnimation.setDuration(duration); 
view.startAnimation(resizeAnimation);

ResizeAnimation class should look like this

public class ResizeAnimation extends Animation {
    final int targetHeight;
    View view;
    int startHeight;

    public ResizeAnimation(View view, int targetHeight, int startHeight) {
        this.view = view;
        this.targetHeight = targetHeight;
        this.startHeight = startHeight;
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        int newHeight = (int) (startHeight + targetHeight * interpolatedTime);
        //to support decent animation, change new heigt as Nico S. recommended in comments
        //int newHeight = (int) (startHeight+(targetHeight - startHeight) * interpolatedTime);
        view.getLayoutParams().height = newHeight;
        view.requestLayout();
    }

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

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