Android：FlutterBoostFragment 里面有PlatformView时候，切到另外一个Tab的FlutterBoostFragment 会crash

liuyicheng3 commented 2 years ago

Steps to Reproduce

1.在 flutterboost example工程修改 “main dart”，把tab_message修改调到example工程里面的NativeViewExample页面 `

  tab_message': (settings, uniqueId) {
    return PageRouteBuilder<dynamic>(

      settings: settings,

      pageBuilder: (_, __, ___) =>

          NativeViewExample());

}

`

run example 工程起来进入 “open flutter fragment page”
切换到朋友Tab 必崩

Flutter Boost Version 4.2.0 Target Platform: Android Target OS version/browser: Android 10 Devices: 荣耀畅玩 9A

Logs

java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first. at android.view.ViewGroup.addViewInner(ViewGroup.java:5327) at android.view.ViewGroup.addView(ViewGroup.java:5156) at android.view.ViewGroup.addView(ViewGroup.java:5096) at android.view.ViewGroup.addView(ViewGroup.java:5069) at io.flutter.plugin.platform.PlatformViewsController.attachToView(PlatformViewsController.java:747) at io.flutter.embedding.android.FlutterView.attachToFlutterEngine(FlutterView.java:1215) at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.onCreateView(FlutterActivityAndFragmentDelegate.java:337) at io.flutter.embedding.android.FlutterFragment.onCreateView(FlutterFragment.java:806) at com.idlefish.flutterboost.containers.FlutterBoostFragment.onCreateView(FlutterBoostFragment.java:92) at com.idlefish.flutterboost.example.tab.FriendFlutterFragment.onCreateView(FriendFlutterFragment.java:19) at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600) at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881) at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238) at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:434) at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManagerImpl.java:2079) at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1869) at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824) at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727) at androidx.fragment.app.FragmentManagerImpl$2.run(FragmentManagerImpl.java:150) at android.os.Handler.handleCallback(Handler.java:900) at android.os.Handler.dispatchMessage(Handler.java:103) at android.os.Looper.loop(Looper.java:219) at android.app.ActivityThread.main(ActivityThread.java:8349) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:513) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1055)

    • Flutter version 3.3.3 on channel stable at /Users/liuyc/fvm/versions/3.3.3
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 18a827f393 (6 weeks ago), 2022-09-28 10:03:14 -0700
    • Engine revision 5c984c26eb
    • Dart version 2.18.2
    • DevTools version 2.15.0

liuyicheng3 commented 2 years ago

因为detachFromFlutterEngine是FlutterBoostFragment在onCreateView做的。

但是super.onCreateView(inflater, container, savedInstanceState) 里面最终会把当前engine的platformview attach上去的操作（也就导致了第二个tab 错误的把第一个tab的platformview再次attach，所以出问题了） flutterEngine.getPlatformViewsController().attachToView(this)

FlutterBoostFragment

  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
            FlutterBoost.instance().getPlugin().onContainerCreated(this);
            View view = super.onCreateView(inflater, container, savedInstanceState);
            flutterView = FlutterBoostUtils.findFlutterView(view);
            // Detach FlutterView from engine before |onResume|.
            flutterView.detachFromFlutterEngine();
            if (DEBUG) Log.d(TAG, "#onCreateView: " + flutterView + ", " + this);
            if (view == flutterView) {
                // fix https://github.com/alibaba/flutter_boost/issues/1732
                FrameLayout frameLayout = new FrameLayout(view.getContext());
                frameLayout.addView(view);
                return frameLayout;
            }
            return view;
        }

joechan-cq commented 2 years ago

目前BoostFragment中的时序如下：

onCreateView(attachEngine -> detachEngine)  -> onResume或者onHiddenChanged (detachEngineIfNeed -> attachEngine)

这个时许中，会出现crash的其实有两个点：

Frgament1 attachEngine后，切换Fragment2，onCreateView中又attachEngine
onCreateView中detachEngine后，onResume中执行detachEngineIfNeed

上述问题的crash点出在1上，解决方法其实就是两次attachEngine中间添加一次detachEngine。但时机不好控制，所以基于目前没有PlatformView的情况下，能够正常运行，那么一个折中的方案就是，在Fragment2 attachEngine之前，把PlatformView从Fragment1的flutterView中移除掉。

但一般无法直接获取到Fragment1中的flutterView，所以这里可以通过继承PlatformViewsController的方法来实现：

public class FlutterBoostPlatformViewsController extends PlatformViewsController {

    public FlutterView mCurrentFlutterView;

    @Override
    public void attachToView(@NonNull FlutterView newFlutterView) {
        super.attachToView(newFlutterView);
        mCurrentFlutterView = newFlutterView;
    }

    @Override
    public void detachFromView() {
        if (mCurrentFlutterView == null) {
            return;
        }
        super.detachFromView();
        mCurrentFlutterView = null;
    }

    public void removePlatformWrapperOrParents() {
        if (mCurrentFlutterView != null) {
            List<View> needRemoveViews = new ArrayList<>();
            int childCount = mCurrentFlutterView.getChildCount();
            for (int i = 0; i < childCount; i++) {
                View view = mCurrentFlutterView.getChildAt(i);
                if (view.getClass().getName().contains("PlatformViewWrapper") || view instanceof FlutterMutatorView) {
                    needRemoveViews.add(view);
                }
            }
            if (!needRemoveViews.isEmpty()) {
                for (View needRemoveView : needRemoveViews) {
                    mCurrentFlutterView.removeView(needRemoveView);
                }
            }
        }
    }
}

然后在构建FlutterEngine的地方使用FlutterBoostPlatformViewsController代替PlatformViewsController。

public FlutterEngine provideFlutterEngine(@NonNull Context context) {
    return new FlutterEngine(
            context,
            null,
            null,
            new FlutterBoostPlatformViewsController(),
            null,
            true,
            false);
}

最后在FlutterBoostFragment的onCreateView方法开始调用removePlatformWrapperOrParents把PlatformView给移掉。

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        FlutterEngine flutterEngine = getFlutterEngine();
        if (flutterEngine != null) {
            PlatformViewsController platformViewsController =
                    flutterEngine.getPlatformViewsController();
            if (platformViewsController instanceof FlutterBoostPlatformViewsController) {
                ((FlutterBoostPlatformViewsController) platformViewsController).removePlatformWrapperOrParents();
            }
        }
        ......
    }

这种方法只能解决attachEngine后又attachEngine的crash，运行后就会出现detachEngine后detachEngineIfNeed的crash点，就是个NPE，解决方法也简单，上面的FlutterBoostPlatformViewsController中已经做了保护，detachFromView中加了空判定。

liuyicheng3 commented 2 years ago

为什么不能在FlutterBoostFragment里面的 didFragmentHide把 performDetach加回来？

 protected void didFragmentHide() {
    FlutterBoost.instance().getPlugin().onContainerDisappeared(this);
    // We defer |performDetach| call to new Flutter container's |onResume|;
    // performDetach();
    if (DEBUG) Log.d(TAG, "#didFragmentHide: " + this + ", isOpaque=" + isOpaque());
}

joechan-cq commented 2 years ago

大概是，无法保证多个Fragment的情况下，可见Fragment的onResume方法和需要hide的fragment的didFragmentHide的方法的调用顺序把。

liuyicheng3 commented 2 years ago

确实有这方面的问题。不过如果是在一个FragmentTransaction 顺序操作多个fragment 就没问题了

marchlqq10 commented 1 year ago

needRemoveViews
这个我试过，可以解决单个fragment的跳转问题。但是，如果是左右2个fragment，右边去加载新的 flutter，会让左边加载的flutter，view remove掉，导致左边不能滚动

joechan-cq commented 1 year ago

needRemoveViews
这个我试过，可以解决单个fragment的跳转问题。但是，如果是左右2个fragment，右边去加载新的 flutter，会让左边加载的flutter，view remove掉，导致左边不能滚动

FlutterBoost的目标场景中，应该不包含这种界面上同时显示两个Fragment的场景

crh2017 commented 1 year ago

这样会导致，返回Frgament1 时，platformView不能的触摸响应的

crh2017 commented 1 year ago

补充下，是从Frgament2返回Frgament1

joechan-cq commented 1 year ago

目前FlutterBoost对PlatformView的支持在生命周期上有比较大的问题，最好还是不要用PlatfomrView吧。

crh2017 commented 1 year ago

调试发现返回Frgament1 时，Frgament2对应FlutterBoostActivity在执行onDestroy时，PlatformViewsController又执行一次detach方法，导致platformViewsChannel被置为空，触摸事件没法传递过来 /**

Detaches this platform views controller.
is typically called when a Flutter applications moves to run in the background, or is
destroyed. After calling this the platform views controller will no longer listen to it's
previous messenger, and will not maintain references to the texture registry, context, and
messenger passed to the previous attach call. */ @UiThread public void detach() { if (platformViewsChannel != null) { platformViewsChannel.setPlatformViewsHandler(null); } destroyOverlaySurfaces(); platformViewsChannel = null; context = null; textureRegistry = null; }

crh2017 commented 1 year ago

这边的临时解决方案背景： flutter 的activity1 frament1 跳转activity2 frament2，frament1 包含platformView，按照上面老哥解决崩溃问题的基础上，出现activity2 frament2返回activity1 frament1时，platformView触摸事件没有响应。问题流程：activity2 frament2返回时，在activity1 frament1 已经在PlatformViewsController已经attach，activity2的onDestroy触发flutterboostfragment的onDetach,最终调用了PlatformViewsController的detach，导致platformViewsChannel销毁了，中断了触摸事件的传递。解决：把platformViewsChannel重新attach，恢复platformViewsChannel，能让activity1 frament1 的platformView重新获取触摸事件。实现： activity2的onDestroy时，异步去调用 flutterEngine.getPlatformViewsController().attach(getContextActivity(), flutterEngine.getRenderer(), flutterEngine.getDartExecutor()); 前提是判断frament1处于可见状态，且处于detach状态兼容： PlatformViewsController在attach时有个判断context是否为空，如下所示： public void attach( @Nullable Context context, @NonNull TextureRegistry textureRegistry, @NonNull DartExecutor dartExecutor) { if (this.context != null) { throw new AssertionError( "A PlatformViewsController can only be attached to a single output target.\n"

"attach was called while the PlatformViewsController was already attached."); } this.context = context; this.textureRegistry = textureRegistry; platformViewsChannel = new PlatformViewsChannel(dartExecutor); platformViewsChannel.setPlatformViewsHandler(channelHandler); } 因此在上面老哥重写的FlutterBoostPlatformViewsController中覆盖attach方法添加detach()下兼容处理，避免快速切换，context不为空的AssertionError问题 @Override public void attach( @Nullable Context context, @NonNull TextureRegistry textureRegistry, @NonNull DartExecutor dartExecutor) { //fixMe super.attach里面需要context为空，否则直接抛异常，而在生命周期里面设置会因为快速点击不够实时设置导致异常 //因此，在attach之前先重置下，当官方解决问题可以移除这个代码 detach(); super.attach(context,textureRegistry,dartExecutor); }

说明：项目比较急，没时间再一一跟进为什么ondestroy为什么调用PlatformViewsController的detach(),把刚刚attach的东西detach掉。当前测试看起来正常，platformView能正常拿到触摸事件，暂没发现别的问题，如果有发现其他新问题，大家讨论下解决方法。后续等解决了，再替换官方的方法

ChinaZeng commented 7 months ago

这个官方有后续的安排吗？

wanghuasheng commented 6 months ago

官方应该不跟进了吧，因为咸鱼没这种场景。

OnClickListener2048 commented 6 months ago

FlutterBoostActivity也有类似的问题

joechan-cq commented 6 months ago

这个我一直想改，但没找到通用合适的方法。Flutter SDK版本太多，对PlatformView的修改也是频繁，又都是私有方法和私有变量，所以改起来非常麻烦。

OnClickListener2048 commented 6 months ago

目前我们线上收到了很多FlutterBoostActivity的问题

这个问题目前能查到的线索是FlutterBoostActivity使用了translucent模式也就是背景是transparent导致了flutterview渲染模式使用了texture，在activity在后台被杀死重启后就会出现该问题

joechan-cq commented 6 months ago

结合之前 @crh2017 这位兄弟的办法，我觉得，可以不用去调用PlatformViewsController.detach方法，这样能够使内部的channelHandler继续响应，解决 #1834 里的内存泄漏问题，同时也能使触摸事件正常响应。

public class FBPlatformViewsController extends PlatformViewsController {

    private Context appCtx;

    /**
     * 记录PlatformViewsController绑定使用的FlutterView
     */
    private FlutterView curFlutterView = null;

    /**
     * 占位FlutterView，用于防止不执行完整detach后，内部channelHandler继续响应时，出现空指针异常。
     */
    private FlutterView dummyFlutterView = null;

    public FBPlatformViewsController() {
        super();
    }

    @Override
    public void attach(@Nullable Context context, @NonNull TextureRegistry textureRegistry,
                       @NonNull DartExecutor dartExecutor) {
        if (appCtx == null && context != null) {
            appCtx = context.getApplicationContext();
            dummyFlutterView = new FlutterView(appCtx);
        }
        super.attach(context, textureRegistry, dartExecutor);
    }

    @Override
    public void detach() {
        // 不执行完整的detach，这样就使内部channelHandler正确响应，同时避免platformView触摸事件无法响应
        // super.detach();
        // 使用反射将内部context变量设置为null，一方面解决重新attach时的异常，另一方面解决内存泄漏
        try {
            Field contextF = getClass().getSuperclass().getDeclaredField("context");
            contextF.setAccessible(true);
            contextF.set(this, null);
        } catch (Exception ignore) {
        }
    }

    @Override
    public void attachToView(@NonNull FlutterView newFlutterView) {
        if (curFlutterView == null) {
            super.attachToView(newFlutterView);
            curFlutterView = newFlutterView;
        } else if (newFlutterView != curFlutterView) {
            removePlatformWrapperOrParents();
            super.attachToView(newFlutterView);
            curFlutterView = newFlutterView;
        }
    }

    @Override
    public void detachFromView() {
        if (curFlutterView != null) {
            super.detachFromView();
            curFlutterView = null;
            //将占位FlutterView绑定上去
            attachToView(dummyFlutterView);
        }
    }

    public void removePlatformWrapperOrParents() {
        if (curFlutterView != null) {
            List<View> needRemoveViews = new ArrayList<>();
            int childCount = curFlutterView.getChildCount();
            for (int i = 0; i < childCount; i++) {
                View view = curFlutterView.getChildAt(i);
                if (view.getClass().getName().contains("PlatformViewWrapper") || view instanceof FlutterMutatorView) {
                    needRemoveViews.add(view);
                }
            }
            if (!needRemoveViews.isEmpty()) {
                for (View needRemoveView : needRemoveViews) {
                    curFlutterView.removeView(needRemoveView);
                }
            }
        }
    }
}

alibaba / flutter_boost

Android：FlutterBoostFragment 里面有PlatformView时候，切到另外一个Tab的FlutterBoostFragment 会crash #1755

Steps to Reproduce

Logs