使用URL下载图像，但在Galery中没有显示

Question

我正在使用此依赖项 image_downloader: ^0.31.0 示例中的代码，问题是它没有显示任何错误，但图像不会进入图库。 此屏幕用于显示来自 firestore 的图像并创建列表样式，当用户单击图像时应该下载它。

import 'dart:io';
import 'dart:async';

import 'package:flutter/services.dart';
import 'package:image_downloader/image_downloader.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:pap_test/upload/upload_resumos_screen.dart';

class DownloadScreen extends StatefulWidget {
  const DownloadScreen({Key? key}) : super(key: key);
  static const routeName = '/downlaod-resumos';

  @override
  State<DownloadScreen> createState() => _DownloadScreenState();
}

class _DownloadScreenState extends State<DownloadScreen> {
  String _message = "";
  String _path = "";
  String _size = "";
  String _mimeType = "";
  File? _imageFile;
  int _progress = 0;
  String query = '1';

  CollectionReference _firebaseFirestore =
      FirebaseFirestore.instance.collection('images');

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Resumos'),
      ),
      body: StreamBuilder<QuerySnapshot>(
        stream: _firebaseFirestore.snapshots().asBroadcastStream(),
        builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
          if (!snapshot.hasData) {
            return Center(
              child: CircularProgressIndicator(),
            );
          } else {
            if (snapshot.data!.docs
                .where((QueryDocumentSnapshot<Object?>
                        element) =>
                    element['disciplina']
                        
                        .toString()
                        .toLowerCase()
                        
                        .contains(query.toLowerCase()))
                .isEmpty) {
              return Center(
                child: Text(
                  'Por aqui está muito lento, carrega no botão e publica um resumo.',
                  style: Theme.of(context).textTheme.headline5,
                  textAlign: TextAlign.center,
                ),
              );
            } else {
              return ListView(
                children: [
                  
                  ...snapshot.data!.docs
                      .where((QueryDocumentSnapshot<Object?>
                              element) => 
                          element['disciplina']
                              
                              .toString()
                              .toLowerCase()
                              
                              .contains(query.toLowerCase()))
                      .map(
                    (QueryDocumentSnapshot<Object?> data) {
                      
                      final String descricao = data.get('descricao');
                      
                      final _image = data['url'];
                      
                      return ListTile(
                        onTap: () {
                          _downloadImage(_image);
                          
                        },
                        
                        leading: CircleAvatar(
                          backgroundImage: NetworkImage(_image),
                        ),

                       
                        title: Text(
                          descricao.toString(),
                          style: Theme.of(context).textTheme.headline5,
                        ),
                      );
                    },
                  )
                ],
              );
            }
          }
        },
      ),
    );
  }

  Future<void> _downloadImage(
    String url, {
    AndroidDestinationType? destination,
    bool whenError = false,
    String? outputMimeType,
  }) async {
    String? fileName;
    String? path;
    int? size;
    String? mimeType;
    try {
      String? imageId;

      if (whenError) {
        imageId = await ImageDownloader.downloadImage(url,
                outputMimeType: outputMimeType)
            .catchError((error) {
          if (error is PlatformException) {
            String? path = "";
            if (error.code == "404") {
              print("Not Found Error.");
            } else if (error.code == "unsupported_file") {
              print("UnSupported FIle Error.");
              path = error.details["unsupported_file_path"];
            }
            setState(() {
              _message = error.toString();
              _path = path ?? '';
            });
          }

          print(error);
        }).timeout(Duration(seconds: 10), onTimeout: () {
          print("timeout");
          return;
        });
      } else {
        if (destination == null) {
          imageId = await ImageDownloader.downloadImage(
            url,
            outputMimeType: outputMimeType,
          );
        } else {
          imageId = await ImageDownloader.downloadImage(
            url,
            destination: destination,
            outputMimeType: outputMimeType,
          );
        }
      }

      if (imageId == null) {
        return;
      }
      fileName = await ImageDownloader.findName(imageId);
      path = await ImageDownloader.findPath(imageId);
      size = await ImageDownloader.findByteSize(imageId);
      mimeType = await ImageDownloader.findMimeType(imageId);
    } on PlatformException catch (error) {
      setState(() {
        _message = error.message ?? '';
      });
      return;
    }

    if (!mounted) return;

    setState(
      () {
        var location = Platform.isAndroid ? "Directory" : "Photo Library";
        _message = 'Saved as "$fileName" in $location.\n';
        _size = 'size:     $size';
        _mimeType = 'mimeType: $mimeType';
        _path = path ?? '';

        if (!_mimeType.contains("video")) {
          _imageFile = File(path!);
        }
        return;
      },
    );
  }
}

这是我单击图像

后的图库

这是我点击