Vfrdtyky

I have two tabs, the left tab having a list of tiles and the right tab having nothing. The user can drag the screen from right-to-left or left-to-right to get from one tab to the other.
The left tab has a list of dismissible tiles that only have "direction: DismissDirection.startToEnd" (from left-to-right) enabled so that the user can still theoretically drag (from right-to-left) to go to the right tab.
However, I believe the Dismissible widget still receives the right-to-left drag information which is disabling the TabView drag to change tabs.

In essence, how do I allow the right-to-left drag to be detected by only the TabView and not the Dismissible item?

If an explicit solution/example with code snippets can be given, I would very very much appreciate the help!

Here's a paste for your main.dart file:

import 'package:flutter/material.dart';

import 'package:flutter/services.dart';

import 'package:flutter/semantics.dart';



void main() {

  SystemChrome.setPreferredOrientations([

    DeviceOrientation.portraitUp,

    DeviceOrientation.portraitDown,

  ]);

  runApp(new MyApp());

}



class MyApp extends StatelessWidget {

  @override

  Widget build(BuildContext context) {

    return MaterialApp(

      theme: ThemeData.dark(),

      home: MainPage(),

    );

  }

}



class MainPage extends StatefulWidget {

  @override

  State<StatefulWidget> createState() => _MainPageState();

}



class _MainPageState extends State<MainPage>

    with SingleTickerProviderStateMixin {

  TabController _tabController;

  @override

  void initState() {

    _tabController = TabController(vsync: this, length: 2, initialIndex: 1);

    super.initState();

  }



  @override

  Widget build(BuildContext context) {

    return Scaffold(

      body: SafeArea(

        child: Container(

          color: Colors.black,

          child: Column(

            crossAxisAlignment: CrossAxisAlignment.stretch,

            mainAxisAlignment: MainAxisAlignment.start,

            children: <Widget>[

              Expanded(

                child: TabBarView(

                  controller: _tabController,

                  children: <Widget>[

                    TabWithSomething(),

                    TabWithNothing(),

                  ],

                ),

              ),

            ],

          ),

        ),

      ),

    );

  }

}



class TabWithNothing extends StatelessWidget {

  @override

  Widget build(BuildContext context) {

    return Center(

      child: Container(

        child: Text("Swipe from left-to-right!"),

      ),

    );

  }

}



class TabWithSomethingItem implements Comparable<TabWithSomethingItem> {

  TabWithSomethingItem({this.index, this.name, this.subject, this.body});



  TabWithSomethingItem.from(TabWithSomethingItem item)

      : index = item.index,

        name = item.name,

        subject = item.subject,

        body = item.body;



  final int index;

  final String name;

  final String subject;

  final String body;



  @override

  int compareTo(TabWithSomethingItem other) => index.compareTo(other.index);

}



class TabWithSomething extends StatefulWidget {

  const TabWithSomething({Key key}) : super(key: key);



  static const String routeName = '/material/leave-behind';



  @override

  TabWithSomethingState createState() => TabWithSomethingState();

}



class TabWithSomethingState extends State<TabWithSomething> {

  List<TabWithSomethingItem> TabWithSomethingItems;



  void initListItems() {

    TabWithSomethingItems =

        List<TabWithSomethingItem>.generate(10, (int index) {

      return TabWithSomethingItem(

          index: index,

          name: 'Item $index',

          subject: 'Swipe from left-to-right to delete',

          body: "Swipe from right-to-left to go back to old tab");

    });

  }



  @override

  void initState() {

    super.initState();

    initListItems();

  }



  void _handleDelete(TabWithSomethingItem item) {

    setState(() {

      TabWithSomethingItems.remove(item);

    });

  }



  @override

  Widget build(BuildContext context) {

    Widget body;

    body = ListView(

        children:

            TabWithSomethingItems.map<Widget>((TabWithSomethingItem item) {

      return _TabWithSomethingListItem(

        item: item,

        onDelete: _handleDelete,

        dismissDirection: DismissDirection.startToEnd,

      );

    }).toList());



    return body;

  }

}



class _TabWithSomethingListItem extends StatelessWidget {

  const _TabWithSomethingListItem({

    Key key,

    @required this.item,

    @required this.onDelete,

    @required this.dismissDirection,

  }) : super(key: key);



  final TabWithSomethingItem item;

  final DismissDirection dismissDirection;

  final void Function(TabWithSomethingItem) onDelete;



  void _handleDelete() {

    onDelete(item);

  }



  @override

  Widget build(BuildContext context) {

    final ThemeData theme = Theme.of(context);

    return Semantics(

      customSemanticsActions: <CustomSemanticsAction, VoidCallback>{

        const CustomSemanticsAction(label: 'Delete'): _handleDelete,

      },

      child: Dismissible(

        key: ObjectKey(item),

        direction: dismissDirection,

        onDismissed: (DismissDirection direction) => _handleDelete(),

        background: Container(

            color: theme.primaryColor,

            child: const ListTile(

                leading: Icon(Icons.delete, color: Colors.white, size: 36.0))),

        child: Container(

          decoration: BoxDecoration(

              color: theme.canvasColor,

              border: Border(bottom: BorderSide(color: theme.dividerColor))),

          child: ListTile(

              title: Text(item.name),

              subtitle: Text('${item.subject}n${item.body}'),

              isThreeLine: true),

        ),

      ),

    );

  }

}

UPDATE:
I'm thinking we could change the "dismissible.dart" file to change the "TabControlller", but i'm not sure how I might do that.

In the "dismissible.dart" file:

...

  void _handleDragUpdate(DragUpdateDetails details) {

    if (!_isActive || _moveController.isAnimating)

      return;



    final double delta = details.primaryDelta;



    if (delta < 0) print(delta);  // thinking of doing something here

...