QR.Flutter is a Flutter library for simple and fast QR code rendering via a Widget or custom painter.

Features

  • Built on QR - Dart
  • Automatic QR code version/type detection or manual entry
  • Supports QR code versions 1 - 40
  • Error correction / redundancy
  • Configurable output size, padding, background and foreground colors
  • Supports image overlays
  • Export to image data to save to file or use in memory
  • No internet connection required

Installing

You should add the following to your pubspec.yaml file:

dependencies:
  qr_flutter: ^3.1.0

Note: If you're using the Flutter master channel, if you encounter build issues, or want to try the latest and greatest then you should use the master branch and not a specific release version. To do so, use the following configuration in your pubspec.yaml:

dependencies:
  qr_flutter:
    git:
      url: git://github.com/lukef/qr.flutter.git

Keep in mind the master branch could be unstable.

After adding the dependency to your pubspec.yaml you can run: flutter packages get or update your packages using your IDE.

Getting started

To start, import the dependency in your code:

import 'package:qr_flutter/qr_flutter.dart';

Next, to render a basic QR code you can use the following code (or something like it):

QrImage(
  data: "1234567890",
  version: QrVersions.auto,
  size: 200.0,
),

Depending on your data requirements you may want to tweak the QR code output. The following options are available:

PropertyTypeDescription
versionintQrVersions.auto or a value between 1 and 40. See http://www.qrcode.com/en/about/version.html for limitations and details.
errorCorrectionLevelintA value defined on QrErrorCorrectLevel. e.g.: QrErrorCorrectLevel.L.
sizedoubleThe (square) size of the image. If not given, will auto size using shortest size constraint.
paddingEdgeInsetsPadding surrounding the QR code data.
backgroundColorColorThe background color (default is none).
foregroundColorColorThe foreground color (default is black).
gaplessboolAdds an extra pixel in size to prevent gaps (default is true).
errorStateBuilderQrErrorBuilderAllows you to show an error state Widget in the event there is an error rendering the QR code (e.g.: version is too low, input is too long, etc).
constrainErrorBoundsboolIf true, the error Widget will be constrained to the square that the QR code was going to be drawn in. If false, the error state Widget will grow/shrink to whatever size it needs.
embeddedImageImageProviderAn ImageProvider that defines an image to be overlaid in the center of the QR code.
embeddedImageStyleQrEmbeddedImageStyleProperties to style the embedded image.
embeddedImageEmitsErrorboolIf true, any failure to load the embedded image will trigger the errorStateBuilder or render an empty Container. If false, the QR code will be rendered and the embedded image will be ignored.

Examples

There is a simple, working, example Flutter app in the /example directory. You can use it to play with all the options.

Also, the following examples give you a quick overview on how to use the library.

A basic QR code will look something like:

QrImage(
  data: 'This is a simple QR code',
  version: QrVersions.auto,
  size: 320,
  gapless: false,
)

A QR code with an image (from your application's assets) will look like:

QrImage(
  data: 'This QR code has an embedded image as well',
  version: QrVersions.auto,
  size: 320,
  gapless: false,
  embeddedImage: AssetImage('assets/images/my_embedded_image.png'),
  embeddedImageStyle: QrEmbeddedImageStyle(
    size: Size(80, 80),
  ),
)

To show an error state in the event that the QR code can't be validated:

QrImage(
  data: 'This QR code will show the error state instead',
  version: 1,
  size: 320,
  gapless: false,
  errorStateBuilder: (cxt, err) {
    return Container(
      child: Center(
        child: Text(
          "Uh oh! Something went wrong...",
          textAlign: TextAlign.center,
        ),
      ),
    );
  },
)

FAQ

Has it been tested in production? Can I use it in production?

Yep! It's stable and ready to rock. It's currently in use in quite a few production applications including:

Outro

Credits

Thanks to Kevin Moore for his awesome QR - Dart library. It's the core of this library.

For author/contributor information, see the AUTHORS file.

License

QR.Flutter is released under a modified MIT license. See LICENSE for details.

Libraries

qr_flutter