如何在 DraggableScrollableSheet 中添加带有固定标题的可滚动选项卡？

Question

我正在尝试使用

NestedScrollView

作为

DraggableScrollableSheet

中的可滚动选项卡，并且需要将工作表的控制器传递到

NestedScrollView

的可滚动主体，但是

NestedScrollView

不支持这样做，这需要内部可滚动项隐式使用上下文的

PrimaryScrollController

。

我所看到的结果是：

1. 可拖动工作表行为是正确的，工作表在滚动前向上移动，但滚动后不会应用标题的标高，标题也不会响应拖动事件（下面的“Foo”选项卡），或者；
2. 与上述相反 - 工作表不响应拖动事件，但正确应用了标题的标高，并且标题本身正确响应滚动手势（下面的“栏”选项卡）

我尝试了

NestedScrollView

、

CustomScrollView

和

TabView

的多种组合，尝试将控制器添加到所有、部分或没有可滚动项。没有运气。我什至尝试监听来自任一附加可滚动项的

Notification

事件，并用这些事件更新另一个可滚动项以尝试保持它们同步。纳达。

非常感谢对此提供的任何帮助，我已经有一段时间了。谢谢！

这是上面视频中

main.dart

的代码：

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.black,
      body: DraggableScrollableSheet(
        initialChildSize: 0.6,
        maxChildSize: 0.9,
        minChildSize: 0.6,
        builder: (context, scrollController) => DefaultTabController(
          length: 2,
          child: _buildNestedScrollView(scrollController),
        ),
      ),
    );
  }

  NestedScrollView _buildNestedScrollView(ScrollController scrollController) {
    return NestedScrollView(
      // controller: scrollController,
      headerSliverBuilder: (context, innerBoxIsScrolled) {
        print('innerBoxIsScrolled $innerBoxIsScrolled');
        return [
          SliverOverlapAbsorber(
            handle: NestedScrollView.sliverOverlapAbsorberHandleFor(context),
            sliver: SliverAppBar(
              toolbarHeight: 0.0,
              pinned: true,
              primary: false,
              forceElevated: innerBoxIsScrolled,
              bottom: TabBar(
                tabs: [
                  Tab(text: 'Foo'),
                  Tab(text: 'Bar'),
                ],
              ),
            ),
          ),
        ];
      },
      body: TabBarView(
        children: [
          ListView.builder(
            controller: scrollController,
            physics: ClampingScrollPhysics(),
            padding: EdgeInsets.zero,
            itemBuilder: (context, index) => Container(
              color: Colors.primaries[index % 10],
              height: 150.0,
            ),
          ),
          ListView.builder(
            // controller: scrollController,
            physics: ClampingScrollPhysics(),
            padding: EdgeInsets.zero,
            itemBuilder: (context, index) => Container(
              color: Colors.primaries[index % 10],
              height: 25.0,
            ),
          ),
        ],
      ),
    );
  }
}

相关链接：

https://api.flutter.dev/flutter/widgets/ScrollableWidgetBuilder.html

https://api.flutter.dev/flutter/widgets/NestedScrollView/body.html

潜在相关的 Flutter 问题。

Answer 1

智能解决方案

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key}) : super(key: key);

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.black,
      body: SizedBox.expand(
        child: DraggableScrollableSheet(
          initialChildSize: 0.6,
          maxChildSize: 0.9,
          minChildSize: 0.6,
          builder: (context, scrollController) => DefaultTabController(
            length: 2,
            child: SafeArea(
                child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                SingleChildScrollView(
                  physics: ClampingScrollPhysics(),
                  controller: scrollController,
                  child: Container(
                    color: Colors.white,
                    child: const TabBar(tabs: [
                      Tab(text: 'Foo'),
                      Tab(text: 'Bar'),
                    ]),
                  ),
                ),
                Expanded(
                  child: TabBarView(
                    children: [
                      ListView.builder(
                        controller: scrollController,
                        physics: ClampingScrollPhysics(),
                        padding: EdgeInsets.zero,
                        itemBuilder: (context, index) => Container(
                          color: Colors.primaries[index % 10],
                          height: 150.0,
                        ),
                      ),
                      ListView.builder(
                        // controller: scrollController,
                        physics: ClampingScrollPhysics(),
                        padding: EdgeInsets.zero,
                        itemBuilder: (context, index) => Container(
                          color: Colors.primaries[index % 10],
                          height: 25.0,
                        ),
                      ),
                    ],
                  ),
                )
              ],
            )),
          ),
        ),
      ),
    );
  }
}