FloatingActionButton.java 文件源码

/**
 * @param circleRect the defined rectangle
 * @param alpha      between  0 - 1
 * @return StateListDrawable
 */
protected StateListDrawable createFillDrawable(RectF circleRect, float alpha) {
    StateListDrawable drawable = new StateListDrawable();
    drawable.addState(new int[]{android.R.attr.state_pressed}, createAlphaDrawble(circleRect, mColorPressed, alpha));
    drawable.addState(new int[]{}, createAlphaDrawble(circleRect, mColorNormal, alpha));
    return drawable;
}