如何在 GridView (Flutter) 中进行分页

Question

我想在 GridView 中实现分页我使用GridView.builder我想在用户到达最后一行时下载 10 x 10 个项目

Answer 1

您可以使用NotificationListener执行此操作。 作为一个简单的演示，它会在到达页面末尾时增加GridView的长度：

    var items_number = 10 ;

    return NotificationListener<ScrollNotification>(
         onNotification: (scrollNotification){
              if(scrollNotification.metrics.pixels == scrollNotification.metrics.maxScrollExtent){
                 setState(() {
                    items_number += 10 ;
                 });    
              }
         },
         child: GridView.builder(
                    itemCount: items_number,
                    itemBuilder: (context, index) {
                      //.... the reminder of your code
                    }
                ),
    );

Answer 2

我也需要这个，但找不到gridview pagination任何小部件，所以我尝试根据下面@Mazin Ibrahim 的回答制作一个组件。 它似乎有效，但不确定这是否是正确的方法。

typedef Future<bool> OnNextPage(int nextPage);

class GridViewPagination extends StatefulWidget {
  final int itemCount;
  final double childAspectRatio;
  final OnNextPage onNextPage;
  final Function(BuildContext context, int position) itemBuilder;
  final Widget Function(BuildContext context) progressBuilder;

  GridViewPagination({
    this.itemCount,
    this.childAspectRatio,
    this.itemBuilder,
    this.onNextPage,
    this.progressBuilder,
  });

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

class _GridViewPaginationState extends State<GridViewPagination> {
  int currentPage = 1;
  bool isLoading = false;

  @override
  Widget build(BuildContext context) {
    return NotificationListener<ScrollNotification>(
      onNotification: (ScrollNotification sn) {
        if (!isLoading && sn is ScrollUpdateNotification && sn.metrics.pixels == sn.metrics.maxScrollExtent) {
          setState(() {
            this.isLoading = true;
          });
          widget.onNextPage?.call(currentPage++)?.then((bool isLoaded) {
            setState(() {
              this.isLoading = false;
            });
          });
        }
        return true;
      },
      child: CustomScrollView(
        slivers: <Widget>[
          SliverGrid(
            gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
              crossAxisSpacing: 1,
              mainAxisSpacing: 1,
              crossAxisCount: 2,
              childAspectRatio: widget.childAspectRatio,
            ),
            delegate: SliverChildBuilderDelegate(
              widget.itemBuilder,
              childCount: widget.itemCount,
              addAutomaticKeepAlives: true,
              addRepaintBoundaries: true,
              addSemanticIndexes: true,
            ),
          ),
          if (isLoading)
            SliverToBoxAdapter(
              child: widget.progressBuilder?.call(context) ?? _defaultLoading(),
            ),
        ],
      ),
    );
  }

  Widget _defaultLoading() {
    return Container(
      padding: EdgeInsets.all(15),
      alignment: Alignment.center,
      child: CircularProgressIndicator(),
    );
  }
}

例子 -

GridViewPagination(
          itemCount: 10,
          childAspectRatio: 1,
          itemBuilder: _buildGridItem,
          onNextPage: (int nextPage) {
            return fetchData();
          },
        )

Answer 3

您可以在此处使用此插件： Paging 。 将您的 GridView 包裹在其中并告诉我这是否有效！

Answer 4

创建一个滚动控制器

ScrollController _scrollController = new ScrollController();

添加滚动事件监听器

@override
  void initState() {
    super.initState();
    _scrollController.addListener(() {
      if (_scrollController.position.pixels ==
          _scrollController.position.maxScrollExtent) {
        // Bottom poistion
      }
    });
  }

现在只需要在你的GridView 、 ListView和 ...

GridView.builder(
     controller: _scrollController,
));