如何在 Flutter 中将图像转换为文件？

Question

我正在编写这个颤振代码，其中我在图像小部件中有图像，我想将其转换为文件，以便我可以将其上传到 Firebase 存储。

Image _image = Image.asset('assets\images\profile.png');
File _fileImage = convertToFile(_image);
//upload _fileImage to Firebase Storage code

我需要File convertToFile(Image img) 函数。

Answer 1

特别感谢sami kanafani。

这是我的解决方案（非常适合我）：

import 'dart:async';
import 'dart:io';
import 'package:flutter/services.dart';
import 'package:path_provider/path_provider.dart';

class ImageUtils {
  static Future<File> imageToFile({String imageName, String ext}) async {
    var bytes = await rootBundle.load('assets/$imageName.$ext');
    String tempPath = (await getTemporaryDirectory()).path;
    File file = File('$tempPath/profile.png');
    await file.writeAsBytes(
        bytes.buffer.asUint8List(bytes.offsetInBytes, bytes.lengthInBytes));
    return file;
  }
}


class AnotherClass {
    File imagePlaceHolder;
    _setPlaceHolder() async {
         this.imagePlaceHolder = await ImageUtils.imageToFile(
         imageName: "photo_placeholder", ext: "jpg");
    }

    ...
    Image.file(this.imagePlaceHolder),
}

Answer 2

我遇到了完全相同的问题，并使用了本指南： https://medium.com/@mrgulshanyadav/convert-image-url-to-file-format-in-flutter-10421bccfd18（作者 Gulshan Yadav）

使用这些导入：

import 'package:http/http.dart' as http;
import 'package:path_provider/path_provider.dart';
import 'dart:io';
import 'dart:math'; 

还有这个功能：

Future<File> urlToFile(String imageUrl) async {
// generate random number.
var rng = new Random();
// get temporary directory of device.
Directory tempDir = await getTemporaryDirectory();
// get temporary path from temporary directory.
String tempPath = tempDir.path;
// create a new file in temporary path with random file name.
File file = new File('$tempPath'+ (rng.nextInt(100)).toString() +'.png');
// call http.get method and pass imageUrl into it to get response.
http.Response response = await http.get(imageUrl);
// write bodyBytes received in response to file.
await file.writeAsBytes(response.bodyBytes);
// now return the file which is created with random name in 
// temporary directory and image bytes from response is written to // that file.
return file;
}

Answer 3

您需要转换资产而不是图像

你需要安装path_provider插件

  var bytes = await rootBundle.load('assets\images\profile.png');
  String tempPath = (await getTemporaryDirectory()).path;
  File file = File('$tempPath/profile.png');
  await file.writeAsBytes(bytes.buffer.asUint8List(bytes.offsetInBytes, bytes.lengthInBytes));

  return file;