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[shared engine][android] Unexpected behavior in detachFromFlutterEngine #94802
Description
The behavior of the |detachFromFlutterEngine| in FlutterActivity/FlutterFragment is NOT as expected.
Please consider the following scenario where multiple FlutterActivities share one FlutterEngine (E.g, flutter_boost):
- Open page A implemented by FlutterActivity A.
- Open page B implemented by FlutterActivity B from page A. (FlutterActivity A is detached from the engine.)
- Go back to the previous page A from page B. (FlutterActivity B is detached from the engine, while FlutterActivity A is reattached.)
Actual results:
As the picture shows when a new Activity is being attached while an existing Activity is already attached, the existing Activity is disposed immediately and can't be reused anymore.
Expected results:
In the scenario of shared-engine, we expect that the detached Activity can be re-attached later instead of being disposed.
flutter doctor -v
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! Doctor found issues in 1 category.
Activity
[-][shared engine][android] The behavior of the detachFromFlutterEngine is not as expected[/-][+][shared engine][android] Unexpected behavior in detachFromFlutterEngine[/+]0xZOne commentedon Dec 8, 2021
An alternative solution is for the developer to implement FlutterActivity/FlutterFragment subclasses to override |detachFromFlutterEngine|.
Or In FlutterActivity/FlutterFragment subclass override |shouldAttachEngineToActivity| to return false, and call flutterEngine.getActivityControlSurface().attachToActivity/detachFromActivity at the right time and place by developer.
But, the precondition is the subclass can access FlutterActivityAndFragmentDelegate (ExclusiveAppComponent<Activity>). (Related PR: flutter-team-archive/engine#30126)
darshankawar commentedon Dec 8, 2021
@0xZOne
Can you provide us a minimal code sample representing above scenarios so that we can verify it further ?
Thanks.
0xZOne commentedon Dec 8, 2021
In fact, the conclusion can be simply obtained from the logic of the above code.
blasten commentedon Dec 8, 2021
Yes, this seems incorrect. cc @gaaclarke
github-actions commentedon Dec 24, 2021
This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of
flutter doctor -vand a minimal reproduction of the issue.