No Transition Page Dart, useful for nested nav

no_transition_page.dart

import 'package:flutter/material.dart';

class NoTransitionPage extends Page<Object> {
  const NoTransitionPage({
    required this.child,
    this.fullscreenDialog = false,
    this.maintainState = true,
    this.barrierColor,
    this.barrierLabel,
  });

  final Widget child;

  final Color? barrierColor;

  final String? barrierLabel;

  /// {@macro flutter.widgets.ModalRoute.maintainState}
  final bool maintainState;

  /// {@macro flutter.widgets.PageRoute.fullscreenDialog}
  final bool fullscreenDialog;

  @override
  Route<Object> createRoute(BuildContext context) =>
      _NoTransitionPageRoute(this);
}

class _NoTransitionPageRoute<T> extends PageRoute<T> {
  _NoTransitionPageRoute(this._page);

  final NoTransitionPage _page;

  @override
  bool get fullscreenDialog => _page.fullscreenDialog;

  @override
  Color? get barrierColor => _page.barrierColor;

  @override
  String? get barrierLabel => _page.barrierLabel;

  @override
  Widget buildPage(
    BuildContext context,
    Animation<double> animation,
    Animation<double> secondaryAnimation,
  ) =>
      _page.child;

  @override
  bool get maintainState => _page.maintainState;

  @override
  Duration get transitionDuration => Duration.zero;
}