页面包含一个带有 LayoutTransition（或 animateLayoutChanges="true"）的 ViewGroup，这会干扰滚动动画

Question

我将 Fragment 与 ViewPager2 一起使用，我注意到在运行 Android 8 或 9 的小米、宇龙、华硕、vivo 等设备中出现了两个相关的 IllegalStateExceptions（我自己无法重现）：

Fatal Exception: java.lang.IllegalStateException: Page can only be offset by a positive amount, not by -758
       at androidx.viewpager2.widget.ScrollEventAdapter.updateScrollEventValues(ScrollEventAdapter.java:280)
       at androidx.viewpager2.widget.ScrollEventAdapter.onScrolled(ScrollEventAdapter.java:178)
       at androidx.recyclerview.widget.RecyclerView.dispatchOnScrolled(RecyclerView.java:5173)
       at androidx.recyclerview.widget.RecyclerView$ViewFlinger.run(RecyclerView.java:5338)
       at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1029)
       at android.view.Choreographer.doCallbacks(Choreographer.java:834)
       at android.view.Choreographer.doFrame(Choreographer.java:760)
       at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1015)
       at android.os.Handler.handleCallback(Handler.java:873)
       at android.os.Handler.dispatchMessage(Handler.java:99)
       at android.os.Looper.loop(Looper.java:224)
       at android.app.ActivityThread.main(ActivityThread.java:7083)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:537)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:928)

和

Fatal Exception: java.lang.IllegalStateException: Page(s) contain a ViewGroup with a LayoutTransition (or animateLayoutChanges="true"), which interferes with the scrolling animation. Make sure to call getLayoutTransition().setAnimateParentHierarchy(false) on all ViewGroups with a LayoutTransition before an animation is started.
       at androidx.viewpager2.widget.ScrollEventAdapter.updateScrollEventValues(ScrollEventAdapter.java:272)
       at androidx.viewpager2.widget.ScrollEventAdapter.onScrolled(ScrollEventAdapter.java:178)
       at androidx.recyclerview.widget.RecyclerView.dispatchOnScrolled(RecyclerView.java:5173)
       at androidx.recyclerview.widget.RecyclerView$ViewFlinger.run(RecyclerView.java:5338)
       at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1029)
       at android.view.Choreographer.doCallbacks(Choreographer.java:841)
       at android.view.Choreographer.doFrame(Choreographer.java:769)
       at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1015)
       at android.os.Handler.handleCallback(Handler.java:794)
       at android.os.Handler.dispatchMessage(Handler.java:99)
       at android.os.Looper.loop(Looper.java:176)
       at android.app.ActivityThread.main(ActivityThread.java:6651)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:824)

在环顾四周时，我通过了以下线程：https : animateLayoutChanges//issuetracker.google.com/issues/129530305，据我所知，它似乎总结为在 viewPager2 的任何父布局上设置为 false，这就是我所做的。不幸的是，这并没有解决我的问题。然后我找到了另一个线程：java.lang.IllegalStateException: Page can only be offset by a positive amount，这似乎没有多大帮助。知道还有什么可能导致问题吗？

Answer 1

您需要在每个页面/片段上执行此操作

 View view = layoutInflater.inflate(R.layout.page, parent, false);
 ViewGroup viewGroup = view.findViewById(R.id.animated_viewgroup);
 viewGroup.getLayoutTransition().setAnimateParentHierarchy(false);

在这里查看官方文档

https://developer.android.com/reference/androidx/viewpager2/widget/ViewPager2

它指出

如果您的页面包含 LayoutTransitions，那么这些 LayoutTransitions 必须将 animateParentHierarchy 设置为 false。请注意，如果您的布局 xml 文件中有一个带有 animateLayoutChanges="true" 的 ViewGroup，则 LayoutTransition 会自动添加到该 ViewGroup。在膨胀 xml 布局后，您需要在该 ViewGroup 上手动调用 getLayoutTransition().setAnimateParentHierarchy(false)。

同样你的错误日志在第一行谈到

Fatal Exception: java.lang.IllegalStateException: Page(s) contain a ViewGroup with a LayoutTransition (or animateLayoutChanges="true"), which interferes with the scrolling animation. Make sure to call getLayoutTransition().setAnimateParentHierarchy(false) on all ViewGroups with a LayoutTransition before an animation is started.