examples/flutter_view/android/app/src/main/res/color/fab_ripple_color.xml

<!-- Copyright 2014 The Flutter Authors. All rights reserved.
Use of this source code is governed by a BSD-style license that can be
found in the LICENSE file. -->

<selector xmlns:android="http://schemas.android.com/apk/res/android">
  <item android:state_pressed="true" android:color="@color/grey" />
  <item android:state_focused="true" android:color="@color/grey" />
  <item android:color="@color/white"/>
</selector>