listview - 转换到另一条路线时，如何使 ListView 保留其滚动？

Question

我想在我的 flutter 应用程序中完成向右滑动的过渡。
问题是路由转换有点创建我想从中转换的页面的新实例，所以 ListView滚动重置。
See a video
这就是我创建新路线的方式

/// @oldRoute needed cause this route transition utilizes `SlideStackRightRoute`
Route createSettingsRoute(Widget oldRoute) {
  return SlideStackRightRoute(exitPage: oldRoute, enterPage: SettingsRoute());
}

最后幻灯片过渡类本身

import 'package:flutter/material.dart';

/// Creates cupertino-like route transition, where new route pushes old from right to left
class SlideStackRightRoute extends PageRouteBuilder {
  final Widget enterPage;
  final Widget exitPage;
  static var exBegin = Offset(0.0, 0.0);
  static var exEnd = Offset(-0.5, 0.0);
  static var entBegin = Offset(1.0, 0.0);
  static var entEnd = Offset.zero;
  static var curveIn = Curves.easeOutSine;
  static var curveOut = Curves.easeInSine;

  SlideStackRightRoute({@required this.exitPage, @required this.enterPage})
      : super(
          transitionDuration: Duration(milliseconds: 400),
          pageBuilder: (
            BuildContext context,
            Animation<double> animation,
            Animation<double> secondaryAnimation,
          ) =>
              enterPage,
          transitionsBuilder: (
            BuildContext context,
            Animation<double> animation,
            Animation<double> secondaryAnimation,
            Widget child,
          ) =>
              Stack(
            children: <Widget>[
              SlideTransition(
                position: Tween(begin: exBegin, end: exEnd)
                    .chain(CurveTween(curve: curveIn))
                    .chain(CurveTween(curve: curveOut))
                    .animate(animation),
                child: Container(
                    foregroundDecoration: BoxDecoration(
                      color: Colors.black.withOpacity(animation.value / 2),
                    ),
                    child: exitPage),
              ),
              SlideTransition(
                position: Tween(begin: entBegin, end: entEnd)
                    .chain(CurveTween(curve: curveIn))
                    .chain(CurveTween(curve: curveOut))
                    .animate(animation),
                child: enterPage,
              )
            ],
          ),
        );
}

Answer 1

我解决这个问题的方法是将偏移量保存到页面类中的静态变量中，并将 Controller 添加到 ListView 构建器中。例如

static double _previousScrollOffset = 0;
final ScrollController _controller = new ScrollController(initialScrollOffset: _previousScrollOffset);

然后每当我导航到新路线时，我都会保存状态。例如

onTap: () {
_previousScrollOffset = _controller.offset;
Navigator.pushNamed<bool>(
    context, ROUTE_ADD_HOUSING + "/" + housing.uuid);   
},