Android: Expand/collapse animation

Question

Let\'s say I have a vertical linearLayout with :

[v1]
[v2]

By default v1 has visibily = GONE. I would like to show v1 with an expand animat

Answer 1

You can use a ViewPropertyAnimator with a slight twist. To collapse, scale the view to a height of 1 pixel, then hide it. To expand, show it, then expand it to its height.

private void collapse(final View view) {
    view.setPivotY(0);
    view.animate().scaleY(1/view.getHeight()).setDuration(1000).withEndAction(new Runnable() {
        @Override public void run() {
            view.setVisibility(GONE);
        }
    });
}

private void expand(View view, int height) {
    float scaleFactor = height / view.getHeight();

    view.setVisibility(VISIBLE);
    view.setPivotY(0);
    view.animate().scaleY(scaleFactor).setDuration(1000);
}

The pivot tells the view where to scale from, default is in the middle. The duration is optional (default = 1000). You can also set the interpolator to use, like .setInterpolator(new AccelerateDecelerateInterpolator())