How to convert an Image instance to File instance in Flutter?

Question

I am using VideoThumbanil class to fetch an Uint8List image of a video like this:

final uint8List = await VideoThumbnail.thumbnailData(video: videoFile.path,);

After doing so, i am converting the Uint8LIST to an Image using the following code:

Image image = Image.memory(uint8List);

What I want to do is to convert this image to a File class instance so that I can upload this image to my server. Code for uploading on server is:

void asyncFileUpload(File file) async {
  //create multipart request for POST or PATCH method
  var request = http.MultipartRequest("POST", Uri.parse("127.0.0.1/upload"));
  //create multipart using filepath, string or bytes
  var pic = await http.MultipartFile.fromPath("image", file.path);
  //add multipart to request
  request.files.add(pic);
  var response = await request.send();
  //Get the response from the server
  var responseData = await response.stream.toBytes();
  var responseString = String.fromCharCodes(responseData);
  print(responseString);
}

Abdul Ahad Akram · Accepted Answer · 2022-06-27 13:40:15Z

3

You can fetch the path to the temporary directory:

final tempDir = await getTemporaryDirectory();

After doing so, you can create a File in that temporary directory:

File fileToBeUploaded = await File('${tempDir.path}/image.png').create();

This way your file has a path and it's instance has been created. Now, you can write the file as:

fileToBeUploaded.writeAsBytesSync(uint8List);

Now, you can use fileToBeUploaded as File that is actually an image.

Complete code:

final uint8List = await VideoThumbnail.thumbnailData(video: videoFile.path,);
final tempDir = await getTemporaryDirectory();
File fileToBeUploaded = await File('${tempDir.path}/image.png').create();
fileToBeUploaded.writeAsBytesSync(uint8List);
asyncFileUpload(fileToBeUploaded);

answered Jun 27, 2022 at 13:40

Abdul Ahad Akram

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Kaushik Chandru · Accepted Answer · 2022-06-25 14:13:33Z

1

Since you already have the uint8 list you can try

File fileTpSend = File.fromRawPath(Uint8List uint8List);

answered Jun 25, 2022 at 14:13

Kaushik Chandru

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2 Comments

Abdul Ahad Akram Over a year ago

I have the uint8List but i don't have it's path, I'll need to store it somewhere to move forward.

Kaushik Chandru Over a year ago

You already have this uint8List as final variable.

Andrii Kovalchuk · Accepted Answer · 2022-06-25 15:08:16Z

1

Based on your code you need to import 'dart:io' and user fromRawPath function from File class (check snippet below)

import 'dart:io';

final uint8List = await VideoThumbnail.thumbnailData(video:videoFile.path);
final imageAsFile = File.fromRawPath(uint8List);
await asyncFileUpload(imageAsFile);

But this method doesn't work for Flutter WEB

edited Jun 25, 2022 at 15:08

answered Jun 25, 2022 at 15:01

Andrii Kovalchuk

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