Restrict overlay in android

Question

Quiz Hacker App is cheating in my quiz app How can I restrict it to draw it's overlay on our app

canDrawOverlays or TYPE_SYSTEM_OVERLAY || TYPE_SYSTEM_OVERLAY

How can I disable any app that hacks?

It uses OCR to read the part of my question and answer and get answer from Google or any other search engine.

Developer implement a Service that allows them to write overlay on our app like this

I want to restrict this service or stop it from taking picture using OCR through our app.

Is there any suggestion to get rid of it like

1. Using a special font that OCR can't read
2. Dim Screen to such extend that OCR can't detect
3. Add any layer or flag on Question and answer part that
4. Ask question in your native language that google can't give right answer
5. Use that type of question that can't be answer by google

Answer 1

Try to add FLAG_SECURE to your activity to prevent it from appearing in screenshots or from being viewed on non-secure displays:

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState);
    window.addFlags(WindowManager.LayoutParams.FLAG_SECURE)
    setContentView(R.layout.activity_main);
}