[英]How to convert Uint8List image to File Image for upload in flutter web
I have have been able to pick a file from my computer and display in my flutter web app.我已经能够从我的计算机中选择一个文件并显示在我的 flutter web 应用程序中。 I have a function(of type File
) which takes a file and uploads it to the server.我有一个函数(类型为File
),它接受一个文件并将其上传到服务器。 like so functionName(File imageToSend)
.就像这样functionName(File imageToSend)
。
But when I try to send this image to the sever side, it gives me an error.但是当我尝试将此图像发送到服务器端时,它给了我一个错误。 Am doing the upload using the code below:我正在使用以下代码进行上传:
Uint8List uploadedImage;
File theChosenImg;
FileReader reader = FileReader();
FileReader reader2 = FileReader();
filePicker() async {
InputElement uploadInput = FileUploadInputElement();
uploadInput.click();
uploadInput.onChange.listen((e) {
// read file content as dataURL
final files = uploadInput.files;
if (files.length == 1) {
final file = files[0];
reader.onLoadEnd.listen((e) {
setState(() {
uploadedImage = reader.result;
theChosenImg = files[0];
});
});
reader.readAsArrayBuffer(file);
reader2.readAsDataUrl(file);
}
});
}
when I use the variable uploadedImage
the error is Expected a value of type 'File', but got one of type 'String'
then I decided to use theChosenImg
from theChosenImg = files[0];
当我使用变量uploadedImage
时,错误是Expected a value of type 'File', but got one of type 'String'
然后我决定使用theChosenImg
中的theChosenImg = files[0];
, this also tell me that the datatypes mismatch. ,这也告诉我数据类型不匹配。
Is it possible for me to convert the Uint8List
datatype to File
?我可以将Uint8List
数据类型转换为File
吗?
UPDATED WITH CODE用代码更新
import 'dart:typed_data';
import 'dart:html';
import 'dart:ui' as ui;
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:web_image_upload/impUp.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
class FrontUi extends StatefulWidget {
@override
_FrontUiState createState() => _FrontUiState();
}
class _FrontUiState extends State<FrontUi> {
Uint8List uploadedImage;
File theChosenImg;
String dispText = 'Uploaded image should shwo here.';
FileReader reader2 = FileReader();
_startFilePicker() async {
InputElement uploadInput = FileUploadInputElement();
uploadInput.click();
uploadInput.onChange.listen((e) {
// read file content as dataURL
final files = uploadInput.files;
if (files.length == 1) {
final file = files[0];
FileReader reader = FileReader();
reader.onLoadEnd.listen((e) {
setState(() {
uploadedImage = reader.result;
theChosenImg = files[0];
});
});
reader.readAsArrayBuffer(file);
reader2.readAsDataUrl(file);
}
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: ListView(
children: <Widget>[
Column(
children: <Widget>[
SizedBox(
height: 30,
),
Container(
height: 500,
width: 800,
child: Center(
child: uploadedImage == null
? Container(
child: Text(dispText),
)
: Container(
child: Image.memory(uploadedImage),
),
),
),
SizedBox(height: 20,),
CupertinoButton(
color: Colors.green,
child: Text("Choose"),
onPressed: (){
_startFilePicker();
},
),
SizedBox(height: 50,),
CupertinoButton(
color: Colors.green,
child: Text("Upload"),
onPressed: (){
PhotoCls().upload(reader2.result);
},
),
],
),
],
),
),
);
}
}
Class with The MEDTHOD WHICH SENDS THE IMAGE Class 与发送图像的方法
import 'dart:io';
import 'package:path/path.dart';
import 'package:async/async.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
class PhotoCls {
String phpEndPoint = "http://IPv4 address/testlocalhost/uploadPicture.php";
upload(File imageFile) async {
// open a bytestream
var stream = new http.ByteStream(DelegatingStream.typed(imageFile.openRead()));
// get file length
var length = await imageFile.length();
// string to uri
var uri = Uri.parse(phpEndPoint);
// create multipart request
var request = new http.MultipartRequest("POST", uri);
// multipart that takes file
var multipartFile = new http.MultipartFile('file', stream, length,
filename: basename(imageFile.path));
// add file to multipart
request.files.add(multipartFile);
// send
var response = await request.send();
print(response.statusCode);
// listen for response
response.stream.transform(utf8.decoder).listen((value) {
print(value);
});
}
}
File.fromRawPath(Uint8List uint8List);
I tried to generate one code who can support both device and web together.我试图生成一个可以同时支持设备和 web 的代码。
Because File.fromRawPath() uses dart:io and its not working for web.因为 File.fromRawPath() 使用 dart:io 并且它不适用于 web。
This is my solution:这是我的解决方案:
Uint8List imageCroppedBytes;
First, I picked my image by image_picker then cropped by extended_image .首先,我通过image_picker选择我的图像,然后通过extended_image裁剪。
Somewhere in my code after cropping I encoded cropped byte file to jpg.裁剪后在我的代码中的某个地方,我将裁剪的字节文件编码为 jpg。
imageCroppedBytes = Image.encodeJpg(src , quality: 80);
Then:然后:
var image = http.MultipartFile.fromBytes('image', imageCroppedBytes ,filename: 'profileImage.jpg');
request.files.add(image);
await request.send().then((value) async {
if(value.statusCode == 200) {
Do Something ...
}
});
In my case I have a NodeJs back with Multer to get the file and save it.就我而言,我有一个与 Multer 一起返回的NodeJ来获取文件并保存它。
Editted:编辑:
import 'package:image/image.dart' as Image;
More code for help:更多帮助代码:
var data = editorKey.currentState.rawImageData;
Image.Image src = Image.decodeImage(data);
src = Image.copyCrop(src, cropRect.left.toInt(), cropRect.top.toInt(),
cropRect.width.toInt(), cropRect.height.toInt());
if(src.width > 300) {
src = Image.copyResize(src,width: 300 , height: 300);
}
setState(() {
imageCroppedBytes = Image.encodeJpg(src , quality: 80);
imagePicked = false;
imageCropped = true;
});
import 'package:path_provider/path_provider.dart';
import 'dart:io';
Uint8List imageInUnit8List = // store unit8List image here ;
final tempDir = await getTemporaryDirectory();
File file = await File('${tempDir.path}/image.png').create();
file.writeAsBytesSync(imageInUnit8List);
// -.-.-.- Unit8List -> File -.-.-.-
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