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Snackbar Method creation

D12 answered on November 14, 2022 Popularity 6/10 Helpfulness 1/10

answer Snackbar Method creation

Snackbar Method creation

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ScaffoldFeatureController<SnackBar, SnackBarClosedReason> showSnackBar(SnackBar snackBar) {
  assert(
    _scaffolds.isNotEmpty,
    'ScaffoldMessenger.showSnackBar was called, but there are currently no '
    'descendant Scaffolds to present to.',
  );
  _snackBarController ??= SnackBar.createAnimationController(vsync: this)
    ..addStatusListener(_handleSnackBarStatusChanged);
  if (_snackBars.isEmpty) {
    assert(_snackBarController!.isDismissed);
    _snackBarController!.forward();
  }
  late ScaffoldFeatureController<SnackBar, SnackBarClosedReason> controller;
  controller = ScaffoldFeatureController<SnackBar, SnackBarClosedReason>._(
    // We provide a fallback key so that if back-to-back snackbars happen to
    // match in structure, material ink splashes and highlights don't survive
    // from one to the next.
    snackBar.withAnimation(_snackBarController!, fallbackKey: UniqueKey()),
    Completer<SnackBarClosedReason>(),
      () {
        assert(_snackBars.first == controller);
        hideCurrentSnackBar();
      },
    null, // SnackBar doesn't use a builder function so setState() wouldn't rebuild it
  );
  try {
    setState(() {
      _snackBars.addLast(controller);
    });
    _updateScaffolds();
  } catch (exception) {
    assert (() {
      if (exception is FlutterError) {
        final String summary = exception.diagnostics.first.toDescription();
        if (summary == 'setState() or markNeedsBuild() called during build.') {
          final List<DiagnosticsNode> information = <DiagnosticsNode>[
            ErrorSummary('The showSnackBar() method cannot be called during build.'),
            ErrorDescription(
              'The showSnackBar() method was called during build, which is '
              'prohibited as showing snack bars requires updating state. Updating '
              'state is not possible during build.',
            ),
            ErrorHint(
              'Instead of calling showSnackBar() during build, call it directly '
              'in your on tap (and related) callbacks. If you need to immediately '
              'show a snack bar, make the call in initState() or '
              'didChangeDependencies() instead. Otherwise, you can also schedule a '
              'post-frame callback using SchedulerBinding.addPostFrameCallback to '
              'show the snack bar after the current frame.',
            ),
            context.describeOwnershipChain(
              'The ownership chain for the particular ScaffoldMessenger is',
            ),
          ];
          throw FlutterError.fromParts(information);
        }
      }
      return true;
    }());
    rethrow;
  }

  return controller;
}

Popularity 6/10 Helpfulness 1/10 Language whatever

Source: api.flutter.dev

Tags: creation snackbar whatever

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Contributed on Nov 14 2022

D12

0 Answers Avg Quality 2/10

Snackbar Method creation

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