使用 Dart 的 Flutter 中的可滚动列表视图

Question

谁能解释我应该在哪里定义滚动控制器？我有聊天列表视图，它是可滚动视图的主体。我希望能够从MainView 控制滚动行为，但不知道如何将控制器传递给_ChatListView。有什么想法吗？

ma​​inview.dart

class MainView extends StatelessWidget {
    ...
    // is this the correct place?
    final ScrollController scrollController = ScrollController();

    @override
    Widget build(BuildContext context) {
        return new Scaffold(
            body: new ChatListView()
        );
    }
}

chatlistview.dart

class ChatListView extends StatefulWidget {
    @override
    _ChatListView createState() => _ChatListView();
}

class _ChatListView extends State< ChatListView > {
    Widget build(BuildContext context) {
        return ListView.builder(
          controller: scrollController,
          );
    }
}

Answer 1

添加构造函数并将控制器作为参数传递

class MainView extends StatelessWidget {
    ...
    // is this the correct place?
    final ScrollController scrollController = ScrollController();

    @override
    Widget build(BuildContext context) {
        return new Scaffold(
            body: new ChatListView(scrollController: scrollController)
        );
    }
}

class ChatListView extends StatefulWidget {
    ChatListView({@required this.scrollController}); 

    final ScrollController scrollController;

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

class _ChatListView extends State< ChatListView > {

    Widget build(BuildContext context) {
        return ListView.builder(
          controller: widget.scrollController,
          );
    }
}