Android上的覆盖屏幕

Question

如何将视图/图像添加到我的主屏幕？

最好的例子是 facebook messenger：如果你长按一个聊天项目，你可以选择“弹出作弊头”，然后你的屏幕上有一个小按钮。

还有一些应用程序，例如屏幕断路器，屏幕损坏的图像会覆盖手机中的所有内容。

我已经搜索过了，但我不知道它叫什么。

希望你们能听懂我的英文。

Answer 1

答案是 SYSTEM_ALERT_WINDOW，这使您能够在 android 中绘制任何东西，与 facebook 用于绘制其聊天头像的功能相同。

http://developer.android.com/reference/android/Manifest.permission.html#SYSTEM_ALERT_WINDOW

示例代码：

    private WindowManager windowManager;
    private ImageView imageView;
   // Get window manager reference

    windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);

    imageView= new ImageView(YOUR_CONTEXT_HERE);
    imageView.setImageResource(R.drawable.android_head);

    // Setup layout parameter
    WindowManager.LayoutParams params = new WindowManager.LayoutParams(
        WindowManager.LayoutParams.WRAP_CONTENT,
        WindowManager.LayoutParams.WRAP_CONTENT,
        WindowManager.LayoutParams.TYPE_PHONE,
        WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
        PixelFormat.TRANSLUCENT);

    params.gravity = Gravity.TOP | Gravity.LEFT; // Orientation
    params.x = 100; // where you want to draw this, coordinates
    params.y = 100;
    // At it to window manager for display, it will be printed over any thing
    windowManager.addView(chatHead, params);


   // Make sure to remove it when you are done, else it will stick there until you reboot
   // Do keep track of same reference of view you added, don't mess with that
   windowManager.removeView(imageView);