Transparent circle inside an activity

Question

I have an activity like this

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:app="http://schemas.android.com/apk/res-auto"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:background="@android:color/transparent"

    tools:context=".WaitingActivity">

</FrameLayout>

and the java code is

@Override

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_waiting);

    getWindow().setLayout(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);

    getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

}

This activity is using dialog theme so whole screen will be 70-80% transparent gray. I need a full transparent circle in center so the activity behind it shows clearly from it. How can I achieve that?

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Answer 1

You may be interested in the PortDuff.Mode. It can be used to set different transfer modes for overlapping views. XOR property can be used to poke a circular hole in an otherwise fullscreen layout so that content beneath becomes visible.

https://developer.android.com/reference/android/graphics/PorterDuff.Mode.html

Transparent circle inside an activity

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