Question

This should be fairly simple, but it is turning out to be more complicated than I thought. How can I apply a ScaleAnimation to a view and get it to stay for the entire duration of a finger press? In other words, while he finger is down shrink the view until the finger is removed, then return it to its original size?
This is what I have tried:

public void onTouch(View v, MotionEvent event)
{
    switch(event.getAction())
    {
    case MotionEvent.ACTION_DOWN
    {
        v.setAnimation(shrinkAnim);
    }
    case MotionEvent.ACTION_UP
    {
        v.setAnimation(growAnim);
    }
    }
}

If I apply setFillEnabled(true) and setFillAfter(true) then the shrink stays indefinitely. If I don’t use it it shrinks for a second then goes back to normal. Thanks ahead of time

Answer 1

It’s a bit unclear what you have and haven’t tried in what combination, so here’s an example that works:

Animation shrink, grow;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    //I chose onCreate(), but make the animations however suits you.
    //The animations need only be created once.

    //From 100% to 70% about center
    shrink = new ScaleAnimation(1.0f, 0.7f, 1.0f, 0.7f, ScaleAnimation.RELATIVE_TO_SELF, 0.5f, ScaleAnimation.RELATIVE_TO_SELF,0.5f);
    shrink.setDuration(200);
    shrink.setFillAfter(true);

    //From 70% to 100% about center
    grow = new ScaleAnimation(0.7f, 1.0f, 0.7f, 1.0f, ScaleAnimation.RELATIVE_TO_SELF,0.5f,ScaleAnimation.RELATIVE_TO_SELF,0.5f);
    grow.setDuration(200);
    grow.setFillAfter(true);
}

@Override
public void onTouch(View v, MotionEvent event) {
    switch(event.getAction()) {
    case MotionEvent.ACTION_DOWN:
        v.startAnimation(shrink);
        break;
    case MotionEvent.ACTION_UP:
        v.startAnimation(grow);
        break;
    default:
        break;
    }
}

The animations should be defined once and reused, with their setFillAfter(true) parameter set; this makes the drawing stick in the final position. When you apply the animations to the view use startAnimation(), setAnimation() is designed for animations that manage their own start times.

Hope that Helps!