java/res/drawable/btn_center.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
/*
**
** Copyright 2011, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
**     http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
-->

<selector
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:exitFadeDuration="@android:integer/config_mediumAnimTime">
    <item
        android:state_window_focused="false"
        android:state_enabled="true"
        android:drawable="@drawable/btn_center_default" />
    <item
        android:state_pressed="true"
        android:drawable="@drawable/btn_center_pressed" />
    <item
        android:state_focused="true"
        android:state_enabled="true"
        android:drawable="@drawable/btn_center_selected" />
    <item
        android:state_enabled="true"
        android:drawable="@drawable/btn_center_default" />
    <item
        android:drawable="@drawable/btn_center_default" />
</selector>