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

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/foundation.dart';

import '../foundation/_features.dart' show isWindowingEnabled;

import '_window.dart'
    show
        BaseWindowController,
        DialogWindowController,
        DialogWindowControllerDelegate,
        WindowEntry,
        WindowRegistry,
        WindowScope;

import 'basic.dart';
import 'debug.dart';
import 'framework.dart';
import 'navigator.dart';
import 'overlay.dart';
import 'routes.dart';

/// A builder for a route that takes the build context and the widget intended
/// to go inside the route as a parameter.
typedef RawDialogRouteBuilder<T> = Route<T> Function(BuildContext context, WidgetBuilder builder);

/// Displays a dialog over the contents of the app.
///
/// {@template flutter.widgets.showRawDialog.windowing}
/// If windowing is enabled via `flutter config --enable-windowing`,
/// then the dialog is displayed in its own window using the windowing system,
/// rather than as a modal overlay within the current window. This will only
/// function on platforms that support the dialog window type. True dialog
/// windows will lack barriers.
/// {@endtemplate}
///
/// The parameter `builder` builds the content of the dialog.
///
/// {@template flutter.widgets.showRawDialog.context}
/// The `context` argument is used to look up the [Navigator] and [Theme] 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.
/// {@endtemplate}
///
/// The parameter `routeBuilder` builds the [Route] that will be pushed to the
/// [Navigator]. Defaults to building a [RawDialogRoute]. When windowing is
/// available, this parameter will be silently ignored.
///
/// {@template flutter.widgets.showRawDialog.navigator}
/// 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. It can not be `null`.
/// {@endtemplate}
///
/// {@template flutter.widgets.showRawDialog.routeSettings}
/// The `routeSettings` argument is passed to [showGeneralDialog],
/// see [RouteSettings] for details.
/// {@endtemplate}
///
/// Returns a [Future] that resolves to the value (if any) that was passed to
/// [Navigator.pop] when the dialog was closed.
///
/// See also:
///
///  * `WindowManager`, for more information on how to set up windowing.
Future<T?> showRawDialog<T>({
  required BuildContext context,
  required WidgetBuilder builder,
  RawDialogRouteBuilder<T>? routeBuilder,
  bool useRootNavigator = true,
  RouteSettings? routeSettings,
  bool fullscreenDialog = false,
}) {
  assert(debugCheckHasWidgetsLocalizations(context));

  final NavigatorState navigator = Navigator.of(context, rootNavigator: useRootNavigator);

  final WindowRegistry? windowRegistry = WindowRegistry.maybeOf(context);
  if (windowRegistry != null && isWindowingEnabled) {
    try {
      final Size? parentSize = WindowScope.maybeContentSizeOf(context);
      return navigator.push<T>(
        _DialogWindowRoute<T>(
          builder: builder,
          parentController: WindowScope.maybeOf(context),
          context: context,
          settings: routeSettings,
          preferredSize: fullscreenDialog ? parentSize : null,
        ),
      );
    } on UnsupportedError catch (error, stacktrace) {
      // Fallback to normal dialog route if windowing is not supported.
      FlutterError.reportError(
        FlutterErrorDetails(exception: error, library: 'widgets library', stack: stacktrace),
      );
    }
  }

  final Route<T> route =
      routeBuilder?.call(context, builder) ??
      RawDialogRoute<T>(
        pageBuilder:
            (
              BuildContext context,
              Animation<double> animation,
              Animation<double> secondaryAnimation,
            ) => builder(context),
        settings: routeSettings,
        fullscreenDialog: fullscreenDialog,
      );

  return navigator.push<T>(route);
}

class _DialogWindowDelegate extends DialogWindowControllerDelegate {
  _DialogWindowDelegate(this.route);

  final _DialogWindowRoute<dynamic> route;

  @override
  void onWindowCloseRequested(DialogWindowController controller) {
    route.navigator?.pop();
  }
}

class _DialogWindowRoute<T> extends Route<T> {
  _DialogWindowRoute({
    required this.builder,
    required this.parentController,
    required BuildContext context,
    super.settings,
    Size? preferredSize,
  }) : _registry = WindowRegistry.maybeOf(context) {
    _controller = DialogWindowController(
      parent: parentController,
      title: 'Dialog',
      delegate: _DialogWindowDelegate(this),
      preferredSize: preferredSize,
    );
  }

  final WidgetBuilder builder;
  final BaseWindowController? parentController;
  final WindowRegistry? _registry;
  DialogWindowController? _controller;
  WindowEntry? _entry;
  late final List<OverlayEntry> _overlayEntries;

  @override
  List<OverlayEntry> get overlayEntries => _overlayEntries;

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

    // Create a minimal transparent overlay entry to satisfy Navigator requirements.
    // The actual dialog content is rendered through ViewAnchor, not through this overlay.
    _overlayEntries = <OverlayEntry>[
      OverlayEntry(builder: (BuildContext context) => const SizedBox.shrink()),
    ];

    final NavigatorState? nav = navigator;
    final BuildContext? routeContext = nav?.context;
    if (routeContext != null && nav != null) {
      _entry = WindowEntry(controller: _controller!, builder: builder);
      _registry?.register(_entry!);
    }
  }

  @override
  TickerFuture didPush() {
    return super.didPush();
  }

  @override
  bool didPop(T? result) {
    if (_entry != null) {
      _registry?.unregister(_entry!);
    }
    _controller?.destroy();
    return super.didPop(result);
  }

  @override
  void dispose() {
    _controller?.dispose();
    _controller = null;
    super.dispose();
  }
}