Android 过渡动画

• 过渡动画
  
  • Scene
  • Transition
  • TransitionManager
  • 代码动画
  • xml动画

过渡动画

过渡动画是在Android 4.4(api>=19)引入的新的动画框架，本质上是对属性动画的封装，方便实现Activity或者View的过渡动画效果。

Scene

Scene定义了页面的当前状态信息，Scene的实例化通过静态工厂方法实现

/*
 * @param sceneRoot The root of the hierarchy in which scene changes
 * and transitions will take place.
 * @param layoutId The id of a standard layout resource file.
 * @param context The context used in the process of inflating
 * the layout resource.
 * @return The scene for the given root and layout id
 */
public static Scene getSceneForLayout(ViewGroup sceneRoot, int layoutId, Context context) 

Transition

Transition定义了界面之前切换的动画信息

TransitionManager

TransitionManager用于控制Scene之间的切换动画效果，切换的常用方法如下：

/*
 * Convenience method to simply change to the given scene using
 * the default transition for TransitionManager.
 *
 * @param scene The Scene to change to
 */
public static void go(Scene scene) {
    changeScene(scene, sDefaultTransition);
}

/**
 * Convenience method to simply change to the given scene using
 * the given transition.
 *
 * <p>Passing in <code>null</code> for the transition parameter will
 * result in the scene changing without any transition running, and is
 * equivalent to calling {@link Scene#exit()} on the scene root's
 * current scene, followed by {@link Scene#enter()} on the scene
 * specified by the <code>scene</code> parameter.</p>
 *
 * @param scene The Scene to change to
 * @param transition The transition to use for this scene change. A
 * value of null causes the scene change to happen with no transition.
 */
public static void go(Scene scene, Transition transition) {
    changeScene(scene, transition);
}

代码动画

首先定义同一页面的两个布局，分别是动画前和动画后的布局，布局如下
动画前：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/scene"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Android" />

</RelativeLayout>

动画后:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/scene"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="Hello Android" />

</RelativeLayout>

动画前的TextView显示在左上角，动画后TextView居中显示
在Activity->onCreate方法中加入

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
    final Scene scene2 = Scene.getSceneForLayout(container, R.layout.fragment_transition_scene_after, this);
    new Handler().postDelayed(new Runnable() {
        @Override
        public void run() {
            TransitionManager.go(scene2);
        }
    }, 3000);
}

首先判断版本大于等于4.4，创建一个Scene对象，加载动画后的布局文件，延时3秒后执行动画 ，使用TransitionManager.go方法。

xml动画

在res目录下创建transition目录(存放过渡动画xml)
创建文件

<?xml version="1.0" encoding="utf-8"?>
<transitionManager xmlns:android="http://schemas.android.com/apk/res/android">

    <transition
        android:fromScene="@layout/fragment_transition_scene_before"
        android:toScene="@layout/fragment_transition_scene_after" />
</transitionManager>

fromScene动画前布局文件
toScene动画后布局文件
Activity->onCreate方法中加入

ViewGroup container = findViewById(R.id.container1);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
    TransitionInflater transitionInflater = TransitionInflater.from(this);
    final TransitionManager mTransitionManager = transitionInflater.inflateTransitionManager(R.transition.transition_manager, container);
    final Scene scene1 = Scene.getSceneForLayout(container, R.layout.fragment_transition_scene_before, this);
    final Scene scene2 = Scene.getSceneForLayout(container, R.layout.fragment_transition_scene_after, this);
    new Handler().postDelayed(new Runnable() {
        @Override
        public void run() {
            mTransitionManager.transitionTo(scene2);
        }
    }, 3000);
}

运行效果和上述代码方式一样，这里使用的默认AutoTransition动画。

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