目标：实现图片的放大至全屏，缩小至原图的动画效果

MainActivity中有两个fragment，firstFragment和secondFragment。

1.在res/transition中定义changebounds.xml文件

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

</changeBounds>

2.在MainActivity中加载firstFragment

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        supportFragmentManager.beginTransaction().add(R.id.root, FirstFragment.newInstance(), "1")
            .addToBackStack(null)
            .commit()
    }

3.分别在fragment_first.xml和fragment_second.xml中图片设置android:transitionName="@string/transition"属性

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".FirstFragment">

    <ImageView
        android:id="@+id/iv_img"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:transitionName="@string/transition"
        android:src="@mipmap/ic_launcher" />

</FrameLayout>

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".SecondFragment">

    <ImageView
        android:id="@+id/iv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@mipmap/ic_launcher"
        android:transitionName="@string/transition"/>

</FrameLayout>

4.在firstFragment中点击图片实现跳转

iv_img.setOnClickListener {
            val mainActivity = activity as MainActivity
            mainActivity.supportFragmentManager.beginTransaction()
                .replace(R.id.root, SecondFragment.newInstance(), "2")
                .addToBackStack(null)
                .setReorderingAllowed(true)
                .addSharedElement(iv_img, getString(R.string.transition))
                .commit()
        }

5.在secondFragment中使用

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        sharedElementEnterTransition = TransitionInflater.from(context).inflateTransition(R.transition.changebounds)
    }

6. 完美完成！