哪些API用于覆盖其他应用程序(如Facebook的Chat Heads)? [英] What APIs are used to draw over other apps (like Facebook's Chat Heads)?

问题描述

Facebook如何在Android上创建聊天头?在所有其他视图之上创建浮动视图的API是什么?

How does Facebook create the Chat Heads on Android? What is the API to create the floating views on top of all other views?

推荐答案

这个一个:

允许应用程序使用类型打开窗口 TYPE_SYSTEM_ALERT，显示在所有其他应用程序的顶部. 很少有应用程序应使用此许可权.这些窗户是专为 与用户进行系统级交互.

Allows an application to open windows using the type TYPE_SYSTEM_ALERT, shown on top of all other applications. Very few applications should use this permission; these windows are intended for system-level interaction with the user.

恒定值:"android.permission.SYSTEM_ALERT_WINDOW"

Constant Value: "android.permission.SYSTEM_ALERT_WINDOW"

// 完整代码此处:

public class ChatHeadService extends Service {

  private WindowManager windowManager;
  private ImageView chatHead;

  @Override public IBinder onBind(Intent intent) {
    // Not used
    return null;
  }

  @Override public void onCreate() {
    super.onCreate();

    windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);

    chatHead = new ImageView(this);
    chatHead.setImageResource(R.drawable.android_head);

    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;
    params.x = 0;
    params.y = 100;

    windowManager.addView(chatHead, params);
  }

  @Override
  public void onDestroy() {
    super.onDestroy();
    if (chatHead != null) windowManager.removeView(chatHead);
  }
}

别忘了以某种方式启动该服务:

Don't forget to start the service somehow:

startService(new Intent(context, ChatHeadService.class));

..并将此服务添加到清单中.

.. And add this service to your Manifest.

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