Support navigation during a Cupertino back gesture by justinmc · Pull Request #142248 · flutter/flutter

justinmc · 2024-01-25T19:47:42Z

Programmatically performing navigation during a Cupertino back gesture was causing buggy state. This PR attempts to fix it by canceling the gesture when any navigation happens.

Currently this is just a proof of concept. It only fixes the case of a pop happening during the gesture, but weird things also happen with a push. I tried it, and if I hold the drag gesture so that it's more than halfway back, then it gets stuck when the push happens.

Listening to isCurrent instead of using PopScope didn't work because the change came after the drag gesture had already ended.

CC @maRci002

Fixes #141268

The example app I was ultimately using to test this

import 'dart:async';

import 'package:flutter/cupertino.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';

class AppScrollBehavior extends MaterialScrollBehavior {
  const AppScrollBehavior();

  @override
  Set<PointerDeviceKind> get dragDevices => const {...PointerDeviceKind.values};
}

void main() {
  runApp(const MainApp());
}

class MainApp extends StatelessWidget {
  const MainApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const CupertinoApp(
      home: ScreenOne(),
    );
  }
}

class ScreenOne extends StatelessWidget {
  const ScreenOne({super.key});

  @override
  Widget build(BuildContext context) {
    return CupertinoPageScaffold(
      child: Center(
        child: TextButton(
          onPressed: () {
            Navigator.of(context).push(
              CupertinoPageRoute(
                title: 'Two',
                builder: (_) => const ScreenTwo(),
              ),
            );
          },
          child: const Text('Go to Screen Two'),
        ),
      ),
    );
  }
}

class ScreenTwo extends StatefulWidget {
  const ScreenTwo({super.key});

  @override
  State<ScreenTwo> createState() => _ScreenTwoState();
}

class _ScreenTwoState extends State<ScreenTwo> {
  int seconds = 5;
  late Timer timer;

  @override
  void initState() {
    super.initState();

    timer = Timer.periodic(
      const Duration(seconds: 1),
      (Timer timer) {
        final ModalRoute<dynamic>? route = ModalRoute.of(context);
        if (!mounted || route == null || !route.isCurrent) {
          timer.cancel();
          return;
        }
        setState(() => seconds--);

        if (seconds == 0) {
          timer.cancel();
          //pop();
          //maybePop();
          navigate();
        }
      },
    );
  }

  @override
  void dispose() {
    timer.cancel();
    super.dispose();
  }

  void pop() {
    Navigator.of(context).pop();
  }

  void maybePop() {
    Navigator.of(context).maybePop();
  }

  void navigate() {
    Navigator.of(context).push(
      CupertinoPageRoute(
        title: 'Three',
        builder: (_) => const ScreenThree(),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return PopScope(
      canPop: true,
      onPopInvoked: (didPop) => print('ScreenTwo onPopInvoked didPop? $didPop'),
      child: CupertinoPageScaffold(
        child: Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Text('Auto pop in: $seconds'),
              const SizedBox(height: 8),
              TextButton(
                onPressed: pop,
                child: const Text('Pop'),
              ),
              const SizedBox(height: 8),
              TextButton(
                onPressed: maybePop,
                child: const Text('Maybe Pop'),
              ),
              const SizedBox(height: 8),
              TextButton(
                onPressed: navigate,
                child: const Text('Go to Screen Three'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class ScreenThree extends StatelessWidget {
  const ScreenThree({super.key});

  @override
  Widget build(BuildContext context) {
    return PopScope(
      canPop: true,
      onPopInvoked: (didPop) =>
          print('ScreenThree onPopInvoked didPop? $didPop'),
      child: const CupertinoPageScaffold(
        child: Center(
          child: Text('Hello World!'),
        ),
      ),
    );
  }
}

pop	push
Screen.Recording.2024-02-01.at.1.50.46.PM.mov	Screen.Recording.2024-02-01.at.1.55.08.PM.mov

justinmc · 2024-01-25T20:07:37Z

packages/flutter/lib/src/cupertino/route.dart

-          child: Listener(
-            onPointerDown: _handlePointerDown,
-            behavior: HitTestBehavior.translucent,
+    return PopScope(


@goderbauer Is there a good way for a route to be informed if it's going to be popped or pushed over? This PopScope setup works for pops, but ideally I want to know if the route has something pushed on top of it, too. I tried watching for changes in PageRoute.isCurrent, but it comes in too late, after the recognizer thinks the drag has ended.

I don't fully understand what you need or are trying to do... Routes have didChangeNext that informs them if something is added (e.g. pushed) on top of them, but I don't know if this comes early enough?

Thanks for the suggestion. I tried didChangeNext/Previous by adding a setState in them when I needed to rebuild, but it didn't rebuild fast enough. Actively reading isCurrent/isActive on the route instead of waiting for it to be passed down seems to be fast enough, though 👍 .

maRci002 · 2024-01-25T22:39:06Z

I think the easiest solution would be to access the current _RouteLifecycle:

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

Line 2931 in 67457e6

_RouteLifecycle currentState;

The Route could have a getter similar to this::

  bool get isOk {
    if (_navigator == null) {
      return false;
    }
    final _RouteEntry? currentRouteEntry = _navigator!
        ._firstRouteEntryWhereOrNull(_RouteEntry.isRoutePredicate(this));

    if (currentRouteEntry == null) {
      return false;
    }

    return !const <_RouteLifecycle>[
      _RouteLifecycle.popping,
      _RouteLifecycle.pushing
    ].contains(currentRouteEntry.currentState);
  }

justinmc · 2024-02-01T22:00:20Z

@maRci002 I tried your approach but I always seemed to read _RouteLifecycle.idle at the time that the drag finished. Just checking isCurrent and isActive seems to work, though.

goderbauer

LGTM

…lutter#142248)

Manual roll Flutter from e02e207 to 0b5cd50 (46 revisions) Manual roll requested by [email protected] flutter/flutter@e02e207...0b5cd50 2024-02-05 [email protected] fix AppBar docs for backgroundColor & foregroundColor (flutter/flutter#142430) 2024-02-04 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Update gradle lockfiles template" (flutter/flutter#142889) 2024-02-04 [email protected] Update gradle lockfiles template (flutter/flutter#140115) 2024-02-04 [email protected] Roll Flutter Engine from 20742e37e54e to f34c658b9600 (1 revision) (flutter/flutter#142876) 2024-02-03 [email protected] Roll Flutter Engine from 23763db72272 to 20742e37e54e (1 revision) (flutter/flutter#142850) 2024-02-03 [email protected] Roll Flutter Engine from fee02145da8c to 23763db72272 (3 revisions) (flutter/flutter#142848) 2024-02-03 [email protected] Roll Flutter Engine from 9869d47a2736 to fee02145da8c (2 revisions) (flutter/flutter#142847) 2024-02-03 [email protected] Roll Flutter Engine from 78c63d3c2c68 to 9869d47a2736 (1 revision) (flutter/flutter#142842) 2024-02-02 [email protected] Roll Flutter Engine from 266d5d0b5588 to 78c63d3c2c68 (1 revision) (flutter/flutter#142836) 2024-02-02 49699333+dependabot[bot]@users.noreply.github.com Bump github/codeql-action from 3.23.2 to 3.24.0 (flutter/flutter#142839) 2024-02-02 49699333+dependabot[bot]@users.noreply.github.com Bump codecov/codecov-action from 3.1.6 to 4.0.1 (flutter/flutter#142838) 2024-02-02 [email protected] Update TextSelectionOverlay (flutter/flutter#142463) 2024-02-02 [email protected] Roll Flutter Engine from e29263212bfd to 266d5d0b5588 (5 revisions) (flutter/flutter#142832) 2024-02-02 [email protected] Fix CupertinoTextSelectionToolbar clipping (flutter/flutter#138195) 2024-02-02 [email protected] Reland "Add support for Gradle Kotlin DSL (#140744)" (flutter/flutter#142752) 2024-02-02 [email protected] Support navigation during a Cupertino back gesture (flutter/flutter#142248) 2024-02-02 [email protected] Avoid depending on files from build_system/targets other than from top level entrypoints in flutter_tools. 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* master: (45 commits) Reverts "Update gradle lockfiles template" (flutter#142889) Update gradle lockfiles template (flutter#140115) Roll Flutter Engine from 20742e3 to f34c658 (1 revision) (flutter#142876) Roll Flutter Engine from 23763db to 20742e3 (1 revision) (flutter#142850) Roll Flutter Engine from fee0214 to 23763db (3 revisions) (flutter#142848) Roll Flutter Engine from 9869d47 to fee0214 (2 revisions) (flutter#142847) Roll Flutter Engine from 78c63d3 to 9869d47 (1 revision) (flutter#142842) Roll Flutter Engine from 266d5d0 to 78c63d3 (1 revision) (flutter#142836) Bump github/codeql-action from 3.23.2 to 3.24.0 (flutter#142839) Bump codecov/codecov-action from 3.1.6 to 4.0.1 (flutter#142838) Update TextSelectionOverlay (flutter#142463) Roll Flutter Engine from e292632 to 266d5d0 (5 revisions) (flutter#142832) Fix CupertinoTextSelectionToolbar clipping (flutter#138195) Reland "Add support for Gradle Kotlin DSL (flutter#140744)" (flutter#142752) Support navigation during a Cupertino back gesture (flutter#142248) Avoid depending on files from build_system/targets other than from top level entrypoints in flutter_tools. (flutter#142760) Roll Packages from 5b48c44 to d37fb0a (14 revisions) (flutter#142812) Add a link the different possible Android virtual device configs (flutter#142765) Allow all iOS tests to use either iOS 16 or 17 (flutter#142714) Roll Flutter Engine from b35153d to e292632 (2 revisions) (flutter#142799) ...

…lutter#142248)

Proof of concept for canceling drag when a pop happens

d423742

justinmc self-assigned this Jan 25, 2024

github-actions bot added framework flutter/packages/flutter repository. See also f: labels. f: cupertino flutter/packages/flutter/cupertino repository f: routes Navigator, Router, and related APIs. labels Jan 25, 2024

justinmc commented Jan 25, 2024

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justinmc mentioned this pull request Jan 25, 2024

[iOS] Back gesture issue with concurrent manual and programmatic pop #141268

Closed

Partial solution for navigating both ways, but not working in some cases

45cc90b

justinmc force-pushed the pop-during-back-gesture branch from 926724d to 45cc90b Compare January 31, 2024 23:52

justinmc added 4 commits February 1, 2024 12:04

Seems to work in all cases. Though maybe animation is jerky.

5aec1eb

Animate the navigation and clean up code

0ee134e

Tests

5daea92

Better explanation in code comments

ad5c1ed

justinmc marked this pull request as ready for review February 1, 2024 22:00

justinmc requested review from LongCatIsLooong and goderbauer February 1, 2024 22:00

Merge branch 'master' into pop-during-back-gesture

c62cd20

goderbauer approved these changes Feb 2, 2024

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Predictive back support for routes #141373

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