1 package com.example.android.xyztouristattractions.ui;
2 
3 import android.animation.Animator;
4 import android.animation.ObjectAnimator;
5 import android.animation.PropertyValuesHolder;
6 import android.annotation.TargetApi;
7 import android.content.Context;
8 import android.os.Build;
9 import android.transition.TransitionValues;
10 import android.transition.Visibility;
11 import android.util.AttributeSet;
12 import android.view.View;
13 import android.view.ViewGroup;
14 
15 /**
16  * A simple scale transition class to allow an element to scale in or out.
17  * This is used by the floating action button on the attraction detail screen
18  * when it appears and disappears during the Activity transitions.
19  */
20 @TargetApi(Build.VERSION_CODES.LOLLIPOP)
21 public class ScaleTransition extends Visibility {
22 
ScaleTransition(Context context, AttributeSet attrs)23     public ScaleTransition(Context context, AttributeSet attrs) {
24         super(context, attrs);
25     }
26 
createAnimation(View view, float startScale, float endScale)27     public Animator createAnimation(View view, float startScale, float endScale) {
28         view.setScaleX(startScale);
29         view.setScaleY(startScale);
30         PropertyValuesHolder holderX = PropertyValuesHolder.ofFloat("scaleX", startScale, endScale);
31         PropertyValuesHolder holderY = PropertyValuesHolder.ofFloat("scaleY", startScale, endScale);
32         return ObjectAnimator.ofPropertyValuesHolder(view, holderX, holderY);
33     }
34 
35     @Override
onAppear(ViewGroup sceneRoot, View view, TransitionValues startValues, TransitionValues endValues)36     public Animator onAppear(ViewGroup sceneRoot, View view, TransitionValues startValues,
37                              TransitionValues endValues) {
38         return createAnimation(view, 0, 1);
39     }
40 
41     @Override
onDisappear(ViewGroup sceneRoot, View view, TransitionValues startValues, TransitionValues endValues)42     public Animator onDisappear(ViewGroup sceneRoot, View view, TransitionValues startValues,
43                                 TransitionValues endValues) {
44         return createAnimation(view, 1, 0);
45     }
46 }