1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.example.android.customtransition; 18 19 import android.animation.Animator; 20 import android.animation.ArgbEvaluator; 21 import android.animation.ObjectAnimator; 22 import android.animation.PropertyValuesHolder; 23 import android.animation.ValueAnimator; 24 import android.graphics.drawable.ColorDrawable; 25 import android.graphics.drawable.Drawable; 26 import android.graphics.drawable.TransitionDrawable; 27 import android.transition.ChangeBounds; 28 import android.transition.Transition; 29 import android.transition.TransitionValues; 30 import android.view.View; 31 import android.view.ViewGroup; 32 import android.view.ViewPropertyAnimator; 33 34 public class ChangeColor extends Transition { 35 36 /** Key to store a color value in TransitionValues object */ 37 private static final String PROPNAME_BACKGROUND = "customtransition:change_color:background"; 38 39 // BEGIN_INCLUDE (capture_values) 40 /** 41 * Convenience method: Add the background Drawable property value 42 * to the TransitionsValues.value Map for a target. 43 */ 44 private void captureValues(TransitionValues values) { 45 // Capture the property values of views for later use 46 values.values.put(PROPNAME_BACKGROUND, values.view.getBackground()); 47 } 48 49 @Override 50 public void captureStartValues(TransitionValues transitionValues) { 51 captureValues(transitionValues); 52 } 53 54 // Capture the value of the background drawable property for a target in the ending Scene. 55 @Override 56 public void captureEndValues(TransitionValues transitionValues) { 57 captureValues(transitionValues); 58 } 59 // END_INCLUDE (capture_values) 60 61 // BEGIN_INCLUDE (create_animator) 62 // Create an animation for each target that is in both the starting and ending Scene. For each 63 // pair of targets, if their background property value is a color (rather than a graphic), 64 // create a ValueAnimator based on an ArgbEvaluator that interpolates between the starting and 65 // ending color. Also create an update listener that sets the View background color for each 66 // animation frame 67 @Override 68 public Animator createAnimator(ViewGroup sceneRoot, 69 TransitionValues startValues, TransitionValues endValues) { 70 // This transition can only be applied to views that are on both starting and ending scenes. 71 if (null == startValues || null == endValues) { 72 return null; 73 } 74 // Store a convenient reference to the target. Both the starting and ending layout have the 75 // same target. 76 final View view = endValues.view; 77 // Store the object containing the background property for both the starting and ending 78 // layouts. 79 Drawable startBackground = (Drawable) startValues.values.get(PROPNAME_BACKGROUND); 80 Drawable endBackground = (Drawable) endValues.values.get(PROPNAME_BACKGROUND); 81 // This transition changes background colors for a target. It doesn't animate any other 82 // background changes. If the property isn't a ColorDrawable, ignore the target. 83 if (startBackground instanceof ColorDrawable && endBackground instanceof ColorDrawable) { 84 ColorDrawable startColor = (ColorDrawable) startBackground; 85 ColorDrawable endColor = (ColorDrawable) endBackground; 86 // If the background color for the target in the starting and ending layouts is 87 // different, create an animation. 88 if (startColor.getColor() != endColor.getColor()) { 89 // Create a new Animator object to apply to the targets as the transitions framework 90 // changes from the starting to the ending layout. Use the class ValueAnimator, 91 // which provides a timing pulse to change property values provided to it. The 92 // animation runs on the UI thread. The Evaluator controls what type of 93 // interpolation is done. In this case, an ArgbEvaluator interpolates between two 94 // #argb values, which are specified as the 2nd and 3rd input arguments. 95 ValueAnimator animator = ValueAnimator.ofObject(new ArgbEvaluator(), 96 startColor.getColor(), endColor.getColor()); 97 // Add an update listener to the Animator object. 98 animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { 99 @Override 100 public void onAnimationUpdate(ValueAnimator animation) { 101 Object value = animation.getAnimatedValue(); 102 // Each time the ValueAnimator produces a new frame in the animation, change 103 // the background color of the target. Ensure that the value isn't null. 104 if (null != value) { 105 view.setBackgroundColor((Integer) value); 106 } 107 } 108 }); 109 // Return the Animator object to the transitions framework. As the framework changes 110 // between the starting and ending layouts, it applies the animation you've created. 111 return animator; 112 } 113 } 114 // For non-ColorDrawable backgrounds, we just return null, and no animation will take place. 115 return null; 116 } 117 // END_INCLUDE (create_animator) 118 119 } 120
