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/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.android.customtransition;
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import android.animation.Animator;
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import android.animation.ArgbEvaluator;
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import android.animation.ObjectAnimator;
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import android.animation.PropertyValuesHolder;
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import android.animation.ValueAnimator;
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import android.graphics.drawable.ColorDrawable;
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import android.graphics.drawable.Drawable;
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import android.graphics.drawable.TransitionDrawable;
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import android.transition.ChangeBounds;
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import android.transition.Transition;
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import android.transition.TransitionValues;
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import android.view.View;
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import android.view.ViewGroup;
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import android.view.ViewPropertyAnimator;
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public class ChangeColor extends Transition {
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/** Key to store a color value in TransitionValues object */
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private static final String PROPNAME_BACKGROUND = "customtransition:change_color:background";
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/**
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* Convenience method: Add the background Drawable property value
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* to the TransitionsValues.value Map for a target.
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*/
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private void captureValues(TransitionValues values) {
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// Capture the property values of views for later use
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values.values.put(PROPNAME_BACKGROUND, values.view.getBackground());
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}
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@Override
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public void captureStartValues(TransitionValues transitionValues) {
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captureValues(transitionValues);
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}
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// Capture the value of the background drawable property for a target in the ending Scene.
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@Override
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public void captureEndValues(TransitionValues transitionValues) {
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captureValues(transitionValues);
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}
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// Create an animation for each target that is in both the starting and ending Scene. For each
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// pair of targets, if their background property value is a color (rather than a graphic),
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// create a ValueAnimator based on an ArgbEvaluator that interpolates between the starting and
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// ending color. Also create an update listener that sets the View background color for each
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// animation frame
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@Override
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public Animator createAnimator(ViewGroup sceneRoot,
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TransitionValues startValues, TransitionValues endValues) {
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// This transition can only be applied to views that are on both starting and ending scenes.
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if (null == startValues || null == endValues) {
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return null;
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}
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// Store a convenient reference to the target. Both the starting and ending layout have the
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// same target.
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final View view = endValues.view;
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// Store the object containing the background property for both the starting and ending
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// layouts.
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Drawable startBackground = (Drawable) startValues.values.get(PROPNAME_BACKGROUND);
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Drawable endBackground = (Drawable) endValues.values.get(PROPNAME_BACKGROUND);
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// This transition changes background colors for a target. It doesn't animate any other
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// background changes. If the property isn't a ColorDrawable, ignore the target.
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if (startBackground instanceof ColorDrawable && endBackground instanceof ColorDrawable) {
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ColorDrawable startColor = (ColorDrawable) startBackground;
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ColorDrawable endColor = (ColorDrawable) endBackground;
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// If the background color for the target in the starting and ending layouts is
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// different, create an animation.
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if (startColor.getColor() != endColor.getColor()) {
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// Create a new Animator object to apply to the targets as the transitions framework
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// changes from the starting to the ending layout. Use the class ValueAnimator,
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// which provides a timing pulse to change property values provided to it. The
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// animation runs on the UI thread. The Evaluator controls what type of
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// interpolation is done. In this case, an ArgbEvaluator interpolates between two
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// #argb values, which are specified as the 2nd and 3rd input arguments.
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ValueAnimator animator = ValueAnimator.ofObject(new ArgbEvaluator(),
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startColor.getColor(), endColor.getColor());
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// Add an update listener to the Animator object.
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animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
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@Override
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public void onAnimationUpdate(ValueAnimator animation) {
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Object value = animation.getAnimatedValue();
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// Each time the ValueAnimator produces a new frame in the animation, change
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// the background color of the target. Ensure that the value isn't null.
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if (null != value) {
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view.setBackgroundColor((Integer) value);
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}
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}
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});
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// Return the Animator object to the transitions framework. As the framework changes
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// between the starting and ending layouts, it applies the animation you've created.
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return animator;
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}
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}
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// For non-ColorDrawable backgrounds, we just return null, and no animation will take place.
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return null;
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}
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}