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 android.transition;
18 
19 import android.animation.Animator;
20 import android.animation.ObjectAnimator;
21 import android.content.Context;
22 import android.transition.Transition;
23 import android.transition.TransitionValues;
24 import android.util.AttributeSet;
25 import android.view.View;
26 import android.view.ViewGroup;
27 
28 /**
29  * This transition captures the scroll properties of targets before and after
30  * the scene change and animates any changes.
31  */
32 public class ChangeScroll extends Transition {
33 
34     private static final String PROPNAME_SCROLL_X = "android:changeScroll:x";
35     private static final String PROPNAME_SCROLL_Y = "android:changeScroll:y";
36 
ChangeScroll()37     public ChangeScroll() {}
38 
ChangeScroll(Context context, AttributeSet attrs)39     public ChangeScroll(Context context, AttributeSet attrs) {
40         super(context, attrs);
41     }
42 
43     @Override
captureStartValues(TransitionValues transitionValues)44     public void captureStartValues(TransitionValues transitionValues) {
45         captureValues(transitionValues);
46     }
47 
48     @Override
captureEndValues(TransitionValues transitionValues)49     public void captureEndValues(TransitionValues transitionValues) {
50         captureValues(transitionValues);
51     }
52 
captureValues(TransitionValues transitionValues)53     private void captureValues(TransitionValues transitionValues) {
54         transitionValues.values.put(PROPNAME_SCROLL_X, transitionValues.view.getScrollX());
55         transitionValues.values.put(PROPNAME_SCROLL_Y, transitionValues.view.getScrollY());
56     }
57 
58     @Override
createAnimator(ViewGroup sceneRoot, TransitionValues startValues, TransitionValues endValues)59     public Animator createAnimator(ViewGroup sceneRoot, TransitionValues startValues,
60             TransitionValues endValues) {
61         if (startValues == null || endValues == null) {
62             return null;
63         }
64         final View view = endValues.view;
65         int startX = (Integer) startValues.values.get(PROPNAME_SCROLL_X);
66         int endX = (Integer) endValues.values.get(PROPNAME_SCROLL_X);
67         int startY = (Integer) startValues.values.get(PROPNAME_SCROLL_Y);
68         int endY = (Integer) endValues.values.get(PROPNAME_SCROLL_Y);
69         Animator scrollXAnimator = null;
70         Animator scrollYAnimator = null;
71         if (startX != endX) {
72             view.setScrollX(startX);
73             scrollXAnimator = ObjectAnimator.ofInt(view, "scrollX", startX, endX);
74         }
75         if (startY != endY) {
76             view.setScrollY(startY);
77             scrollYAnimator = ObjectAnimator.ofInt(view, "scrollY", startY, endY);
78         }
79         return TransitionUtils.mergeAnimators(scrollXAnimator, scrollYAnimator);
80     }
81 }
82