颤音：Image.Memory小部件无法加载

Question

我们正在尝试创建自定义画廊页面，以便我们遵循了一些教程网站，但是面对某些问题无法编译该项目。

教程链接::

https://medium.com/@mhstoller.it/how-to/how-to-to-create-create-a-custom-custom-media-media-picker-in-picker-in-picker-in-picker-in-flutter-to-in-flutter-to-select----------- photos-and-videos-from-the-the-the-the-the-988eea477643

class MediaGrid extends StatefulWidget {
  @override
  _MediaGridState createState() => _MediaGridState();
}
class _MediaGridState extends State<MediaGrid> {
  List<Widget> _mediaList = [];
  int currentPage = 0;
  late int lastPage;
  @override
  void initState() {
    super.initState();
    _fetchNewMedia();
  }
  _handleScrollEvent(ScrollNotification scroll) {
    if (scroll.metrics.pixels / scroll.metrics.maxScrollExtent > 0.33) {
      if (currentPage != lastPage) {
        _fetchNewMedia();
      }
    }
  }
  Future<ui.Image> loadImage(Uint8List img) async {
    final Completer<ui.Image> completer = Completer();
    ui.decodeImageFromList(img, (ui.Image img) {
      return completer.complete(img);
    });
    return completer.future;
  }
  static Future<ui.Image> bytesToImage(Uint8List imgBytes) async{
    ui.Codec codec = await ui.instantiateImageCodec(imgBytes);
    ui.FrameInfo frame = await codec.getNextFrame();
    return frame.image;
  }

  _fetchNewMedia() async {
    lastPage = currentPage;

    final PermissionState _ps = await PhotoManager.requestPermissionExtend();
    if (_ps.isAuth) {
      // success
//load the album list
      List<AssetPathEntity> albums =
      await PhotoManager.getAssetPathList(onlyAll: true);
      print(albums);
      List<AssetEntity> media =
      await albums[0].getAssetListPaged(page: currentPage, size: 60);
      // await albums[0].getAssetListPaged(currentPage, 60);
      List<Widget> temp = [];
      for (var asset in media) {
        temp.add(
          FutureBuilder(
            future: asset.thumbnailDataWithSize(const ThumbnailSize(200, 200)),
            builder: (BuildContext context, snapshot) {
              if (snapshot.connectionState == ConnectionState.done) {
                return Stack(
                  children: [
                    // Image.asset(
                    //   "assets/images/gallery.png",
                    //   fit: BoxFit.cover,
                    // ),
                    Positioned.fill(
                      child: Image.memory(
                        snapshot.data,
                        fit: BoxFit.cover,
                      ),
                    ),
                    if (asset.type == AssetType.video)
                      const Align(
                        alignment: Alignment.bottomRight,
                        child: Padding(
                          padding: EdgeInsets.only(right: 5, bottom: 5),
                          child: Icon(
                            Icons.videocam,
                            color: Colors.white,
                          ),
                        ),
                      ),
                  ],
                );
              }
              return Container();
            },
          ),
        );
      }
      setState(() {
        _mediaList.addAll(temp);
        currentPage++;
      });
    } else {
      // fail
      /// if result is fail, you can call `PhotoManager.openSetting();`  to open android/ios applicaton's setting to get permission
    }
  }
  @override
  Widget build(BuildContext context) {
    return NotificationListener<ScrollNotification>(
      onNotification: (ScrollNotification scroll) {

         return _handleScrollEvent(scroll);
      },
      child: GridView.builder(
          itemCount: _mediaList.length,
          gridDelegate:
          const SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 3),
          itemBuilder: (BuildContext context, int index) {
            return _mediaList[index];
          }),
    );
  }
}

以下代码不起作用，

Positioned.fill(
                      child: Image.memory(
                        snapshot.data,**//Error here**
                        fit: BoxFit.cover,
                      ),
                    ),

我将依赖项更新为 photo_manager 2.1.2 和更改所需方法因此。

Answer 1

最后，它在类型施​​放后工作。

snapshot.data as Uint8List,



Positioned.fill(
                      child: Image.memory(
                        snapshot.data! as Uint8List,
                        fit: BoxFit.cover,
                      ),
                    ),