How to draw a timer on top of other applications?

Question

Android

How to make a transparent application that will not respond to input events, but pass them to the application below it? Or should it be done through a service that will draw on top of other applications?
The task is to draw the timer in the foreground, on top of all other applications.

Answer 1

Here I love to dig towards the overlay.
Only your application will need an additional permission.)

public class OverlayService extends Service {

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

        WindowManager windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);

        View overlay = /*  Твоя вью сдесь*/;

        WindowManager.LayoutParams params = new WindowManager.LayoutParams(
            WindowManager.LayoutParams.WRAP_CONTENT,
            WindowManager.LayoutParams.WRAP_CONTENT,
            WindowManager.LayoutParams.TYPE_SYSTEM_ALERT,
            WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE,
            PixelFormat.TRANSLUCENT);
        windowManager.addView(overlay , params);
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }   
}

Don't forget to add to your manifest
and start it
You can disable tachi through
WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE