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我正在尝试从内存中加载图像，我的方法是给出Future<Uint8List>但Image.memory需要Uint8List颤抖

这是错误消息参数类型Future<Uint8List>不能分配给参数类型`Uint8List

我在这里使用图像

import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:image_puzzle/function.dart';
import 'package:image_puzzle/getimages.dart';
import 'widgets.dart';

class HomePage extends StatefulWidget {
const HomePage({Key? key}) : super(key: key);

 @override
 State<HomePage> createState() => _HomePageState();
 }

 class _HomePageState extends State<HomePage> {
  bool gotImage = false;

  Future<Uint8List> downloadImage() async {
  var readWriteObj = ReadAndWrite();
  var imgData = await readWriteObj.getImages();
  readWriteObj
    .writeDataToFile('image1', imgData)
    .then((value) => {print('Image Saved ')});
  return imgData;
 }

 readImage() async {
  var image = ReadAndWrite().
  writeDataToFile('image1', await ReadAndWrite().getImages());
return image;
 }

 double aopacity = 1;
 double aopacity1 = 1;
 double aopacity2 = 1;
 double aopacity3 = 1;
 double aopacity4 = 1;
 double aopacity5 = 1;
 double aopacity6 = 1;
 double aopacity7 = 1;
 double aopacity8 = 1;

 @override
 void initState() {
  downloadImage();
  // readImage();
  super.initState();
}

 @override
 Widget build(BuildContext context) {
  List<BrainOfApp> questionList = [];
 int listNumber = 0;
 questionList.add(BrainOfApp('salman',

    // 'https://cdn.pixabay.com/photo/2020/11/16/04/41/salman-khan-5747949_960_720.png',
    ['elon musk', 'sachin', 'salman', 'mahi']));
return Scaffold(
    appBar: AppBar(
      title: const Text('Bollywood Quiz'),
      backgroundColor: Colors.black,
    ),
    body: Stack(children: [
      Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Expanded(
            child: Center(
              child: Stack(
                fit: StackFit.expand,
                children: [
                  Image.memory(downloadImage()),
                  Column(
                    children: [
                      Expanded(
                        child: Row(
                          children: [
                            CoverTile(aopacity),
                            CoverTile(aopacity1),
                            CoverTile(aopacity2)
                          ],
                        ),
                      ),
                      Expanded(
                        child: Row(
                          children: [
                            CoverTile(aopacity3),
                            CoverTile(aopacity4),
                            CoverTile(aopacity5),
                          ],
                        ),
                      ),
                      Expanded(
                        child: Row(
                          children: [
                            CoverTile(aopacity6),
                            CoverTile(aopacity7),
                            CoverTile(aopacity8),
                          ],
                        ),
                      )
                    ],
                  ),
                ],
              ),
            ),
          ),
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              const SizedBox(
                width: 20,
              ),
              Expanded(
                child: ElevatedButton(
                    child: Text(
                      questionList[listNumber].options![0].toUpperCase(),
                      style: const TextStyle(fontSize: 24),
                    ),
                    style: ButtonStyle(
                      foregroundColor:
                          MaterialStateProperty.all<Color>(Colors.white),
                      backgroundColor:
                          MaterialStateProperty.all<Color>(Colors.black),
                      shape:
                          MaterialStateProperty.all<RoundedRectangleBorder>(
                        RoundedRectangleBorder(
                          borderRadius: BorderRadius.circular(20),
                          side: const BorderSide(color: Colors.white70),
                        ),
                      ),
                    ),
                    onPressed: () {
                      listNumber++;
                    }),
              ),
              const SizedBox(
                width: 60,
              ),
              Expanded(
                child: ElevatedButton(
                    child: Text(
                      questionList[listNumber].options![1].toUpperCase(),
                      style: const TextStyle(fontSize: 24),
                    ),
                    style: ButtonStyle(
                      foregroundColor:
                          MaterialStateProperty.all<Color>(Colors.white),
                      backgroundColor:
                          MaterialStateProperty.all<Color>(Colors.black),
                      shape:
                          MaterialStateProperty.all<RoundedRectangleBorder>(
                        RoundedRectangleBorder(
                          borderRadius: BorderRadius.circular(20),
                          side: const BorderSide(color: Colors.white70),
                        ),
                      ),
                    ),
                    onPressed: () {
                      listNumber++;
                    }),
              ),
              const SizedBox(
                width: 20,
              ),
            ],
          ),
          const SizedBox(height: 60),
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              const SizedBox(
                width: 20,
              ),
              Expanded(
                child: ElevatedButton(
                    child: Text(
                      questionList[listNumber].options![2].toUpperCase(),
                      style: const TextStyle(fontSize: 24),
                    ),
                    style: ButtonStyle(
                      foregroundColor:
                          MaterialStateProperty.all<Color>(Colors.white),
                      backgroundColor:
                          MaterialStateProperty.all<Color>(Colors.black),
                      shape:
                          MaterialStateProperty.all<RoundedRectangleBorder>(
                        RoundedRectangleBorder(
                          borderRadius: BorderRadius.circular(20),
                          side: const BorderSide(color: Colors.white70),
                        ),
                      ),
                    ),
                    onPressed: () {
                      listNumber++;
                    }),
              ),
              const SizedBox(
                width: 60,
              ),
              Expanded(
                child: ElevatedButton(
                    child: Text(
                      questionList[listNumber].options![3].toUpperCase(),
                      style: const TextStyle(fontSize: 24),
                    ),
                    style: ButtonStyle(
                      foregroundColor:
                          MaterialStateProperty.all<Color>(Colors.white),
                      backgroundColor:
                          MaterialStateProperty.all<Color>(Colors.black),
                      shape:
                          MaterialStateProperty.all<RoundedRectangleBorder>(
                        RoundedRectangleBorder(
                          borderRadius: BorderRadius.circular(20),
                          side: const BorderSide(color: Colors.white70),
                        ),
                      ),
                    ),
                    onPressed: () {
                      listNumber++;
                    }),
              ),
              const SizedBox(
                width: 20,
              ),
            ],
          ),
          const SizedBox(height: 60),
        ],
      )
    ]));
 }
 }

这是读写类

    import 'dart:io';
import 'dart:typed_data';
import 'package:http/http.dart';
import 'package:path_provider/path_provider.dart';

    class ReadAndWrite {
  Future<Uint8List> getImages() async {
var url = Uri.parse(
    'https://cdn.pixabay.com/photo/2020/11/16/04/41/salman-khan-5747949_960_720.png');
Response response = await get(url);
var bytes = response.bodyBytes;
return bytes;
}

Future<String> get _localPath async {
  final directory = await getApplicationDocumentsDirectory();
  print(directory.path);
  return directory.path;
  }

Future<File> getLocalFile(String fileName) async {
final localPath = await _localPath;
return File('$localPath/$fileName');
}

 Future<File> writeDataToFile(String fileName, Uint8List data) async {
final file = await getLocalFile(fileName);
return file.writeAsBytes(data);
}

Future<Uint8List> readFromFile(String fileName) async {
final file = await getLocalFile(fileName);
return file.readAsBytes();
}
}

问题是，我正在尝试从内存中加载图像，但是，我的方法将来会给出字节，但是Image.memory小部件将来会接受

我也不能在那个小部件中使用 await 。

4

1 回答 1

0

使用FutureBuilder：

FutureBuilder<Uint8List>(
  future: downloadImage(),
  builder: (context, snapshot) {
    if (snapshot.hasError) {
      // Show some widget in error state
      return const Text('Error Loading Image');
    } else if (snapshot.hasData) {
      // Show the image when retrieved successfully
      return Image.memory(snapshot.data!);
    } else {
      // Show some widget while loading
      return const CircularProgressIndicator();
    }
  },
);
于 2021-12-30T01:51:56.607 回答