Cupertino route/transition should block touch events

[machinescream]

I think block any touch events during Cupertino transition is reasonable.

[VladyslavBondarenko]

Hi @Renesanse
could you describe and provide a minimal complete code sample to the cases when it is reasonable?

[machinescream]

Hi @Renesanse
could you describe and provide a minimal complete code sample to the cases when it is reasonable?

Navigator.of(context).push(CupertinoPageRoute(builder: (_) => Container()));

[VladyslavBondarenko]

@Renesanse
it doesn't answer the question. Why do you think it is reasonable?

[machinescream]

Because handling touch events during transitions and animations is bad practice. Users will be confused about actions in the app cause miss clicking happens during screen transitions. I am very surprised that you are don't know it and I need to explain to you why this is necessary.
In iOS touch events is prevented by default when screen transition in progress.

[xster]

The premise is reasonable. We theoretically already do

flutter/packages/flutter/lib/src/widgets/routes.dart

Line 791 in 534b060

return IgnorePointer(

. This might be a bug.

[chunhtai]

@xster This is actually not blocking anything, it only blocks when the route is offstage or in the middle of back swipe

[willlockwood]

Just letting folks know that I'm putting up a change for this soon 👍🏻

[chunhtai]

#104520
pr is reverted

[chunhtai]

https://test.corp.google.com/ui?legacy=true#id=OCL:449917835:BASE:450085441:1653089130425:637cfbc1

[willlockwood]

Huh, @chunhtai what was the issue here? Anything I can help with?

[chunhtai]

I have not investigated what is wrong, but here is a more detailed stack trace

══╡ EXCEPTION CAUGHT BY FOUNDATION LIBRARY ╞════════════════════════════════════════════════════════
The following assertion was thrown while dispatching notifications for ValueNotifier<bool>:
setState() or markNeedsBuild() called during build.
This AnimatedBuilder widget cannot be marked as needing to build because the framework is already in
the process of building widgets. A widget can be marked as needing to be built during the build
phase only if one of its ancestors is currently building. This exception is allowed because the
framework builds parent widgets before children, which means a dirty descendant will always be
built. Otherwise, the framework might not visit this widget during this build phase.
The widget on which setState() or markNeedsBuild() was called was:
  AnimatedBuilder
The widget which was currently being built when the offending call was made was:
  Builder

When the exception was thrown, this was the stack:
#0      Element.markNeedsBuild.<anonymous closure> (package:flutter/src/widgets/framework.dart:4477)
#1      Element.markNeedsBuild (package:flutter/src/widgets/framework.dart:4492)
#2      State.setState (package:flutter/src/widgets/framework.dart:1129)
#3      _AnimatedState._handleChange (package:flutter/src/widgets/transitions.dart:127)
#4      ChangeNotifier.notifyListeners (package:flutter/src/foundation/change_notifier.dart:341)
#5      ValueNotifier.value= (package:flutter/src/foundation/change_notifier.dart:445)
#6      ModalRoute._maybeUpdateIgnorePointer (package:flutter/src/widgets/routes.dart:1429)
#7      ModalRoute._handleAnimationStatusChanged (package:flutter/src/widgets/routes.dart:1186)
#8      AnimationLocalStatusListenersMixin.notifyStatusListeners (package:flutter/src/animation/listener_helpers.dart:233)
#9      AnimationLocalStatusListenersMixin.notifyStatusListeners (package:flutter/src/animation/listener_helpers.dart:233)
#10     AnimationLocalStatusListenersMixin.notifyStatusListeners (package:flutter/src/animation/listener_helpers.dart:233)
#11     CompoundAnimation._maybeNotifyStatusListeners (package:flutter/src/animation/animations.dart:677)
#12     AnimationLocalStatusListenersMixin.notifyStatusListeners (package:flutter/src/animation/listener_helpers.dart:233)
#13     AnimationController._checkStatusChanged (package:flutter/src/animation/animation_controller.dart:815)
#14     AnimationController._animateToInternal (package:flutter/src/animation/animation_controller.dart:607)
#15     AnimationController.reverse (package:flutter/src/animation/animation_controller.dart:494)
#16     TransitionRoute.didPop (package:flutter/src/widgets/routes.dart:262)
#17     LocalHistoryRoute.didPop (package:flutter/src/widgets/routes.dart:682)
#18     _RouteEntry.handlePop (package:flutter/src/widgets/navigator.dart:2888)
#19     NavigatorState._flushHistoryUpdates (package:flutter/src/widgets/navigator.dart:3860)
#20     NavigatorState.pop (package:flutter/src/widgets/navigator.dart:4916)

[machinescream]

I have implemented couple of months ago this route, you can take a look at this and try to replicate its behaviour. https://github.com/machinescream/right/blob/main/lib/src/r_route.dart