On Android, How to create global screen overlay for my app?

Question

I want to display some icon as alert for my app.

I know there are screen dimmer/filter apps that can do the thing on Android, but I cannot find technical reference on the topic from google.

Anyone can point me the way?

Answer 1

• using context.getSystemService(Context.WINDOW_SERVICE) to get a WindowManager

• create layoutParams: WindowManager.LayoutParams(-2, -2, TYPE_APPLICATION_OVERLAY, 0, PixelFormat.TRANSLUCENT)

• create view using context

• then use WindowManager.addView

• may need to add permission android.permission.SYSTEM_ALERT_WINDOW