packages/Keyguard/res/anim/keyguard_security_fade_in.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2012 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

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     distributed under the License is distributed on an "AS IS" BASIS,
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     See the License for the specific language governing permissions and
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<alpha xmlns:android="http://schemas.android.com/apk/res/android"
    android:interpolator="@android:interpolator/decelerate_quad"
    android:fromAlpha="0.0" android:toAlpha="1.0"
    android:duration="@integer/kg_security_fade_duration" />