Android: Overlay-Fenster, über die Aktivitäten einer Aufgabe

Ich glaube, das folgende wird für Sie von Interesse sein. Sie wird nicht verlangen android.permission.SYSTEM_ALERT_WINDOW. Der code ist für die Anwendung Klasse.

Kommentare sollen Ihnen helfen, die Logik zu verstehen. Der code sollte funktionieren direkt aus der box.

public class YourApplication extends Application {

    //Popup to show persistent view
    PopupWindow pw;

    //View held by Popup
    LinearLayout ll;

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

        //Register for Activity Lifecyle Callbacks 
        registerActivityLifecycleCallbacks(new YourCallBack());

        //Initialize the view  
        ll = new LinearLayout(this);        
        ll.setLayoutParams(new LayoutParams(100, 100));     
        ll.setBackgroundColor(Color.BLUE);

        //Initialize popup 
        pw = new PopupWindow(ll, 100, 100);     

        //Set popup's window layout type to TYPE_TOAST     
        Method[] methods = PopupWindow.class.getMethods();
        for(Method m: methods){
            if(m.getName().equals("setWindowLayoutType")) {
                try{
                    m.invoke(pw, WindowManager.LayoutParams.TYPE_TOAST);
                }catch(Exception e){
                    e.printStackTrace();
                }
                break;
            }
        }       
    }

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

        if (pw != null && pw.isShowing()) {
            pw.dismiss();
        }
    };



    private final class YourCallBack implements ActivityLifecycleCallbacks {

        int numOfRunning = 0;

        @Override
        public void onActivityCreated(Activity arg0, Bundle arg1) { }

        @Override
        public void onActivityDestroyed(Activity arg0) { }

        @Override
        public void onActivityPaused(Activity arg0) {

            //An activity has been paused
            //Decrement count, but wait for a certain
            //period of time, in case another activity
            //from this application is being launched
            numOfRunning--;

            //Delay: 100 ms
            //If no activity's onResumed() was called,
            //its safe to assume that the application
            //has been paused, in which case, dismiss
            //the popup            
            new Handler().postDelayed(new Runnable() {

                @Override
                public void run() {
                    if (numOfRunning == 0) {
                        pw.dismiss();
                    }
                }
            }, 100L);
        }

        @Override
        public void onActivityResumed(Activity arg0) {

            //If no activities were running, show the popup
            if (numOfRunning == 0) {
                pw.showAtLocation(ll, Gravity.BOTTOM, 0, 0);
            }

            //Now, one activity is running         
            numOfRunning++;
        }

        @Override
        public void onActivitySaveInstanceState(Activity arg0, Bundle arg1) { }

        @Override
        public void onActivityStarted(Activity arg0) { }

        @Override
        public void onActivityStopped(Activity arg0) { }

    };
}