Capture button release in Android

You should set an OnTouchListener on your button.

button.setOnTouchListener(new OnTouchListener() {
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        if(event.getAction() == MotionEvent.ACTION_DOWN) {
            increaseSize();
        } else if (event.getAction() == MotionEvent.ACTION_UP) {
            resetSize();
        }
    }
};

You have to handle MotionEvent.ACTION_CANCEL as well. So the code will be:

button.setOnTouchListener(new OnTouchListener() {
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_UP || 
            event.getAction() == MotionEvent.ACTION_CANCEL) {
            increaseSize();
        } else if (event.getAction() == MotionEvent.ACTION_UP) {
            resetSize();
        }
    }
};

use an OnTouchListener or OnKeyListener instead.

You might be able to do this by overriding the onKeyDown and onKeyUp. These are both inherited from android.widget.TextView. Please see the android.widget.Button doc for (a bit) more info.