///  * [DisplayFeatureSubScreen], which documents the specifics of how
///    [DisplayFeature]s can split the screen into sub-screens.
///  * [showDialog], which displays a Material-style dialog.
///  * [showCupertinoDialog], which displays an iOS-style dialog.
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(!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,
  ));
}

实现很简单，直接调用Navigator的push方法打开了一个新的对话框路由RawDialogRoute，然后返回了push的返回值。可见对话框实际上正是通过路由的形式实现的，这也是为什么我们可以使用Navigator的pop 方法来退出对话框的原因。关于对话框的样式定制在RawDialogRoute中，没有什么新的东西，读者可以自行查看。这里我只取一部分

class RawDialogRoute<T> extends PopupRoute<T> {
  /// A general dialog route which allows for customization of the dialog popup.
  RawDialogRoute({
    required RoutePageBuilder pageBuilder,
    bool barrierDismissible = true,
    Color? barrierColor = const Color(0x80000000),
    String? barrierLabel,
    Duration transitionDuration = const Duration(milliseconds: 200),
    RouteTransitionsBuilder? transitionBuilder,
    super.settings,
    this.anchorPoint,
    super.traversalEdgeBehavior,
  }) : _pageBuilder = pageBuilder,
       _barrierDismissible = barrierDismissible,
       _barrierLabel = barrierLabel,
       _barrierColor = barrierColor,
       _transitionDuration = transitionDuration,
       _transitionBuilder = transitionBuilder;

    ---....此处省略----
}