Create a ImageView effect when press

gistfile1.txt

    @Override
    public boolean onTouchEvent(MotionEvent event) {

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                Drawable drawable = getDrawable();
                if (drawable != null) {
                    drawable.mutate().setColorFilter(Color.GRAY, PorterDuff.Mode.MULTIPLY);
                }
                break;
            case MotionEvent.ACTION_MOVE:
                break;
            case MotionEvent.ACTION_CANCEL:
            case MotionEvent.ACTION_UP:
                Drawable drawableUp = getDrawable();
                if (drawableUp != null) {
                    drawableUp.mutate().clearColorFilter();
                }
                break;
        }

        return super.onTouchEvent(event);
    }

实现点击图片 变暗的操作