View的点击泛黑显示效果

老的方法都是FrameLayout加一个foreground，这里是用自定义view去实现

public class PressedTextView extends AppCompatTextView {

    public PressedTextView(Context context) {
        super(context);
    }

    public PressedTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public PressedTextView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (isPressed()) {
            canvas.drawColor(0x33000000);
        }
    }

    @Override
    protected void dispatchSetPressed(boolean pressed) {
        super.dispatchSetPressed(pressed);
        invalidate();
    }
}