基本思路:

方法1.遮罩可直接叠加一层带alpha的纯白、或纯黑View,可直接在ImageView外套一层FrameLayout,其foreground(一般同学可能仅仅知道background,事实上framelayout还有foreground)给定一个selector(按下时给0x33000000,即泛黑),到位。

方法2.重写imageView,按下状态改变时invalidate(触发onDraw),onDraw中依据按下状态绘制0x33000000。注意imageView.setClickable(true),或imageView.setOnClickListener时才可触发dispatchSetPressed。

@Override

	public void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);

		setContentView(R.layout.activity_main);

		// 取id

		// imgTest = (ImageView) findViewById(R.id.imgTest);

		loMain = (RelativeLayout) findViewById(R.id.loMain);

		findViewById(R.id.btn1).setOnClickListener(this);

		findViewById(R.id.btn2).setOnClickListener(this);

		MyImg myImg = new MyImg(this);

		myImg.setImageResource(R.drawable.meinv);

		myImg.setClickable(true);

		loMain.addView(myImg);

	}

	private class MyImg extends ImageView {

		public MyImg(Context context) {

			super(context);

		}

		@Override

		protected void onDraw(Canvas canvas) {

			// TODO Auto-generated method stub

			super.onDraw(canvas);

			if (isPressed())

				canvas.drawColor(0x33000000);

		}

		@Override

		protected void dispatchSetPressed(boolean pressed) {

			// TODO Auto-generated method stub

			super.dispatchSetPressed(pressed);

			invalidate();

		}

	}

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