[Windows] Clipboard.setData stops copy once malformed character appears in the String

import 'dart:convert';
import 'dart:io';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

Future<void> main() async {
  runApp(const MyApp());

  final Uint8List readFile =
      await File(r'C:\Windows\System32\vcruntime140_1.dll').readAsBytes();

  final String tryUtf8 = utf8.decode(readFile, allowMalformed: true);
  print('UTF8 File as String: $tryUtf8');

  final String charcodes = String.fromCharCodes(readFile);
  print('Charcodes File as String: $tryUtf8');

  await Clipboard.setData(ClipboardData(text: tryUtf8));
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headlineMedium,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}

File content that we read with utf8

What is copied to clipboard

File content that we read with charcodes

What is copied to clipboard

Flutter doctor -v

PS C:\Users\swiftsoft\Desktop\test_project> flutter doctor -v
[√] Flutter (Channel stable, 3.27.3, on Microsoft Windows [Version 10.0.26100.2605], locale en-US)
    • Flutter version 3.27.3 on channel stable at c:\flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision c519ee916e (5 days ago), 2025-01-21 10:32:23 -0800
    • Engine revision e672b006cb
    • Dart version 3.6.1
    • DevTools version 2.40.2

[√] Windows Version (Installed version of Windows is version 10 or higher)

[X] Android toolchain - develop for Android devices
    • Android SDK at C:\Users\swiftsoft\AppData\Local\Android\sdk
    X cmdline-tools component is missing
      Run `path/to/sdkmanager --install "cmdline-tools;latest"`
      See https://developer.android.com/studio/command-line for more details.

[X] Chrome - develop for the web (Cannot find Chrome executable at .\Google\Chrome\Application\chrome.exe)
    ! Cannot find Chrome. Try setting CHROME_EXECUTABLE to a Chrome executable.

[√] Visual Studio - develop Windows apps (Visual Studio Community 2022 17.11.5)
    • Visual Studio at C:\Program Files\Microsoft Visual Studio\2022\Community
    • Visual Studio Community 2022 version 17.11.35327.3
    • Windows 10 SDK version 10.0.22621.0

[!] Android Studio (not installed)
    • Android Studio not found; download from https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/to/windows-android-setup for detailed instructions).

[√] IntelliJ IDEA Community Edition (version 2024.3)
    • IntelliJ at C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2024.2.4
    • Flutter plugin version 83.0.4
    • Dart plugin version 243.23177

[√] Connected device (2 available)
    • Windows (desktop) • windows • windows-x64    • Microsoft Windows [Version 10.0.26100.2605]
    • Edge (web

@krll-kov

Hi @krll-kov, curious, does this still occur if you read the string directly without reading from a file first? Assuming you just copy the output from the console and try to set that in the clipboard, does it still cut off?

Hi @krll-kov, curious, does this still occur if you read the string directly without reading from a file first? Assuming you just copy the output from the console and try to set that in the clipboard, does it still cut off?

You can not read file as sting since it has malformed characters(for utf8 decoder), as for copy, you can copy it from console/notepad without any problems (manually, without flutter)

And if you mean to create a var with manually copied string and try to copy it, then yes, it works

And if you mean to create a var with manually copied string and try to copy it, then yes, it works

Yes, this is what I meant. Does this work as expected on the web? I want to confirm if this is specific to the windows platform or if it reproduces on other platforms as well. It would help if we could get a sample that doesn't rely on a windows specific file.

Thank you

And if you mean to create a var with manually copied string and try to copy it, then yes, it works

Yes, this is what I meant. Does this work as expected on the web? I want to confirm if this is specific to the windows platform or if it reproduces on other platforms as well. It would help if we could get a sample that doesn't rely on a windows specific file.

Thank you

I do not know, I'm windows developer and have no idea of it's possible to read files on web, please,check that manually

I use the file_selector plugin to select some files that should contain some malformed characters and tested the sample on windows and macOS. On macOS, the clipboard appeared to retain all data but on windows, it got cut off after a certain point.

Steps to reproduce

Run the sample code below
Click on the fab
Select the cache.dill.track.dill file from the build folder and wait for the logs to be printed (at this point, the clipboard should have the data) On windows, you can just select the dll file from the OP
Attempt to paste what is in the clipboard

Reproduces on stable & master

complete sample

import 'dart:convert';
import 'dart:io';

import 'package:file_selector/file_selector.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

void main() {
  runApp(const MainApp());
}

class MainApp extends StatelessWidget {
  const MainApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: HomeScreen(),
    );
  }
}

class HomeScreen extends StatefulWidget {
  const HomeScreen({
    super.key,
  });

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(
        onPressed: () async {

        final file = await openFile();

          if (file != null) {
            final Uint8List readFile = await File(file.path).readAsBytes();

            final String tryUtf8 = utf8.decode(readFile, allowMalformed: true);
            print('UTF8 File as String: $tryUtf8');

            final String charcodes = String.fromCharCodes(readFile);
            print('Charcodes File as String: $tryUtf8');

            await Clipboard.setData(ClipboardData(text: tryUtf8));
          }
        },
        child: Icon(Icons.save),
      ),
    );
  }
}

[√] Flutter (Channel master, 3.29.0-1.0.pre.164, on Microsoft Windows [Version 10.0.22631.4751], locale en-US) [7.4s]
    • Flutter version 3.29.0-1.0.pre.164 on channel master at C:\Users\Deana\fvm\versions\master
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 7313c87346 (4 hours ago), 2025-01-29 23:52:56 -0500
    • Engine revision 7313c87346
    • Dart version 3.8.0 (build 3.8.0-24.0.dev)
    • DevTools version 2.42.0

Fix null terminator in input truncates clipboard (flutter#188652)

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[Windows] Clipboard.setData stops copy once malformed character appears in the String #162226

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[Windows] Clipboard.setData stops copy once malformed character appears in the String #162226

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danagbemava-nc commented on Jan 28, 2025

krll-kov commented on Jan 28, 2025

krll-kov commented on Jan 28, 2025

danagbemava-nc commented on Jan 29, 2025

krll-kov commented on Jan 29, 2025

danagbemava-nc commented on Jan 30, 2025

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github-actions commented on Aug 5, 2026

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