How to read bytes of a local image file in Dart/Flutter?

With Flutter environment, you have to use AssetBundle if you want to access to your assets (https://flutter.io/assets-and-images/).

import 'package:flutter/services.dart' show rootBundle;ByteData bytes = await rootBundle.load('assets/placeholder.png');

In dart Uint8List is equal to byte[].

1. Create one function and pass file path, It will return Bytes.

   Future<Uint8List> _readFileByte(String filePath) async {    Uri myUri = Uri.parse(filePath);    File audioFile = new File.fromUri(myUri);    Uint8List bytes;    await audioFile.readAsBytes().then((value) {    bytes = Uint8List.fromList(value);     print('reading of bytes is completed');  }).catchError((onError) {      print('Exception Error while reading audio from path:' +      onError.toString());  });  return bytes;}

2. Now call the function in to get bytes of file.

   try{  Uint8List audioByte;  String myPath= 'MyPath/abc.png';  _readFileByte(myPath).then((bytesData) {    audioByte = bytesData;  //do your task here   });} catch (e) {   // if path invalid or not able to read  print(e);}

3. If you want base64String then use below code:

   String audioString = base64.encode(audioByte);

for base64 import 'dart:convert';

I hope it will help!

Here is an example to read file byte by byte:

import 'dart:io';void main(List<String> arguments) {  readFileByteByByte().then((done) {    print('done');  });  print('waiting...');  print('do something else while waiting...');}Future<bool> readFileByteByByte() async {  //final fileName = 'C:\\code\\test\\file_test\\bin\\main.dart'; // use your image file name here  final fileName = Platform.script.toFilePath(); //this will read this text file as an example  final script = File(fileName);  final file = await script.open(mode: FileMode.read);  var byte;  while (byte != -1) {    byte = await file.readByte();    if (byte == ';'.codeUnitAt(0)) { //check if byte is semicolon      print(byte);    }  }  await file.close();  return (true);}