showGeneralDialog<T extends Object?> function Null safety

Future<T?> showGeneralDialog<T extends Object?>(

{required BuildContext context,
required RoutePageBuilder pageBuilder,
bool barrierDismissible = false,
String? barrierLabel,
Color barrierColor = const Color(0x80000000),
Duration transitionDuration = const Duration(milliseconds: 200),
RouteTransitionsBuilder? transitionBuilder,
bool useRootNavigator = true,
RouteSettings? routeSettings,
Offset? anchorPoint}

)

Displays a dialog above the current contents of the app.

This function allows for customization of aspects of the dialog popup.

This function takes a pageBuilder which is used to build the primary content of the route (typically a dialog widget). Content below the dialog is dimmed with a ModalBarrier. The widget returned by the pageBuilder does not share a context with the location that showGeneralDialog is originally called from. Use a StatefulBuilder or a custom StatefulWidget if the dialog needs to update dynamically. The pageBuilder argument can not be null.

The context argument is used to look up the Navigator for the dialog. It is only used when the method is called. Its corresponding widget can be safely removed from the tree before the dialog is closed.

The useRootNavigator argument is used to determine whether to push the dialog to the Navigator furthest from or nearest to the given context. By default, useRootNavigator is true and the dialog route created by this method is pushed to the root navigator.

If the application has multiple Navigator objects, it may be necessary to call Navigator.of(context, rootNavigator: true).pop(result) to close the dialog rather than just Navigator.pop(context, result).

The barrierDismissible argument is used to determine whether this route can be dismissed by tapping the modal barrier. This argument defaults to false. If barrierDismissible is true, a non-null barrierLabel must be provided.

The barrierLabel argument is the semantic label used for a dismissible barrier. This argument defaults to null.

The barrierColor argument is the color used for the modal barrier. This argument defaults to Color(0x80000000).

The transitionDuration argument is used to determine how long it takes for the route to arrive on or leave off the screen. This argument defaults to 200 milliseconds.

The transitionBuilder argument is used to define how the route arrives on and leaves off the screen. By default, the transition is a linear fade of the page's contents.

The routeSettings will be used in the construction of the dialog's route. See RouteSettings for more details.

A DisplayFeature can split the screen into sub-screens. The closest one to anchorPoint is used to render the content.

If no anchorPoint is provided, then Directionality is used:

for TextDirection.ltr, anchorPoint is Offset.zero, which will cause the content to appear in the top-left sub-screen.
for TextDirection.rtl, anchorPoint is Offset(double.maxFinite, 0), which will cause the content to appear in the top-right sub-screen.

If no anchorPoint is provided, and there is no Directionality ancestor widget in the tree, then the widget asserts during build in debug mode.

Returns a Future that resolves to the value (if any) that was passed to Navigator.pop when the dialog was closed.

State Restoration in Dialogs

Using this method will not enable state restoration for the dialog. In order to enable state restoration for a dialog, use Navigator.restorablePush or Navigator.restorablePushNamed with RawDialogRoute.

For more information about state restoration, see RestorationManager.

This sample demonstrates how to create a restorable dialog. This is accomplished by enabling state restoration by specifying WidgetsApp.restorationScopeId and using Navigator.restorablePush to push RawDialogRoute when the button is tapped.

To test state restoration on Android:

Turn on "Don't keep activities", which destroys the Android activity as soon as the user leaves it. This option should become available when Developer Options are turned on for the device.
Run the code sample on an Android device.
Create some in-memory state in the app on the phone, e.g. by navigating to a different screen.
Background the Flutter app, then return to it. It will restart and restore its state.

To test state restoration on iOS:

Open ios/Runner.xcworkspace/ in Xcode.
(iOS 14+ only): Switch to build in profile or release mode, as launching an app from the home screen is not supported in debug mode.
Press the Play button in Xcode to build and run the app.
Create some in-memory state in the app on the phone, e.g. by navigating to a different screen.
Background the app on the phone, e.g. by going back to the home screen.
Press the Stop button in Xcode to terminate the app while running in the background.
Open the app again on the phone (not via Xcode). It will restart and restore its state.

To create a local project with this code sample, run:
flutter create --sample=widgets.showGeneralDialog.1 mysample

import 'package:flutter/material.dart';

void main() => runApp(const GeneralDialogApp());

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

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      restorationScopeId: 'app',
      home: GeneralDialogExample(),
    );
  }
}

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: OutlinedButton(
          onPressed: () {
            /// This shows an alert dialog.
            Navigator.of(context).restorablePush(_dialogBuilder);
          },
          child: const Text('Open Dialog'),
        ),
      ),
    );
  }

  static Route<Object?> _dialogBuilder(
      BuildContext context, Object? arguments) {
    return RawDialogRoute<void>(
      pageBuilder: (
        BuildContext context,
        Animation<double> animation,
        Animation<double> secondaryAnimation,
      ) {
        return const AlertDialog(title: Text('Alert!'));
      },
    );
  }
}

Implementation

Future<T?> showGeneralDialog<T extends Object?>({
  required BuildContext context,
  required RoutePageBuilder pageBuilder,
  bool barrierDismissible = false,
  String? barrierLabel,
  Color barrierColor = const Color(0x80000000),
  Duration transitionDuration = const Duration(milliseconds: 200),
  RouteTransitionsBuilder? transitionBuilder,
  bool useRootNavigator = true,
  RouteSettings? routeSettings,
  Offset? anchorPoint,
}) {
  assert(pageBuilder != null);
  assert(useRootNavigator != null);
  assert(!barrierDismissible || barrierLabel != null);
  return Navigator.of(context, rootNavigator: useRootNavigator).push<T>(RawDialogRoute<T>(
    pageBuilder: pageBuilder,
    barrierDismissible: barrierDismissible,
    barrierLabel: barrierLabel,
    barrierColor: barrierColor,
    transitionDuration: transitionDuration,
    transitionBuilder: transitionBuilder,
    settings: routeSettings,
    anchorPoint: anchorPoint,
  ));
}

Flutter
widgets
showGeneralDialog<T extends Object?> function

showGeneralDialog<T extends Object?> function Null safety

State Restoration in Dialogs

Implementation

widgets library