/qr.flutter

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

Primary LanguageDartBSD 3-Clause "New" or "Revised" LicenseBSD-3-Clause

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

Need help?

Please do not submit an issue for a "How do i ..?" or "What is the deal with ..?" type question. They will pretty much be closed instantly. If you have questions, please ask them on the Discussions board or on Stack Overflow. They will get answered there.

Using issues creates a large amount of noise and results in real issues getting fixed slower.

Features

  • Null safety
  • 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

Version compatibility: 4.0.0+ supports null safety and requires a version of Flutter that is compatible. If you're using an incompatible version of flutter, please use a 3.x version of this library.

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

dependencies:
  qr_flutter: ^4.1.0

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: https://github.com/theyakka/qr.flutter

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):

QrImageView(
  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:

Property Type Description
version int QrVersions.auto or a value between 1 and 40. See http://www.qrcode.com/en/about/version.html for limitations and details.
errorCorrectionLevel int A value defined on QrErrorCorrectLevel. e.g.: QrErrorCorrectLevel.L.
size double The (square) size of the image. If not given, will auto size using shortest size constraint.
padding EdgeInsets Padding surrounding the QR code data.
backgroundColor Color The background color (default is none).
eyeStyle QrEyeStyle Configures the QR code eyes' (corners') shape and color.
dataModuleStyle QrDataModuleStyle Configures the shape and the color of the dots.
gapless bool Adds an extra pixel in size to prevent gaps (default is true).
errorStateBuilder QrErrorBuilder Allows 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).
constrainErrorBounds bool If 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.
embeddedImage ImageProvider An ImageProvider that defines an image to be overlaid in the center of the QR code.
embeddedImageStyle QrEmbeddedImageStyle Properties to style the embedded image.
embeddedImageEmitsError bool If 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.
semanticsLabel String semanticsLabel will be used by screen readers to describe the content of the QR code.
borderRadius double Setting corner rounding for shape types QrEyeShape.square, QrDataModuleShape.square, EmbeddedImageShape.square. Set in appropriate styles.
roundedOutsideCorners bool If true, the outer corners of the data are rounded. Set to QrDataModuleStyle. Rounded to borderRadius by default. Only QrDataModuleShape.square.
outsideBorderRadius double It is set if the outer rounding outsideBorderRadius should differ from the inner one borderRadius. No more than borderRadius. Only QrDataModuleShape.square
gradient Gradient Changing the solid color of the code to a gradient, e.g. LinearGradient.
safeArea bool If true, data is hidden behind the embeddedImage. Set to QrEmbeddedImageStyle.
safeAreaMultiplier double Multiplier safeArea size.

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:

QrImageView(
  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:

QrImageView(
  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:

QrImageView(
  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,
        ),
      ),
    );
  },
)

A QR code with inside and outside corners rounding and safe area of embedded image:

QrImageView(
  data: 'London is the capital of Great Britain',
  version: QrVersions.auto,
  size: 320,
  eyeStyle: const QrEyeStyle(
    borderRadius: 10,
  ),
  dataModuleStyle: const QrDataModuleStyle(
    borderRadius: 5,
    roundedOutsideCorners: true,
  ),
  embeddedImage: AssetImage('assets/images/my_embedded_image.png'),
  embeddedImageStyle: QrEmbeddedImageStyle(
    size: Size.square(40),
    color: Colors.white,
    safeArea: true,
    safeAreaMultiplier: 1.1,
    embeddedImageShape: EmbeddedImageShape.square,
    borderRadius: 10,
  ),
)

A QR code with gradient:

QrImageView(
  data: 'Rainbow after the rain',
  version: QrVersions.auto,
  size: 320,
  gradient: LinearGradient(
    begin: Alignment.bottomLeft,
    end: Alignment.topRight,
      colors: [
      Color(0xffff0000),
      Color(0xffffa500),
      Color(0xffffff00),
      Color(0xff008000),
      Color(0xff0000ff),
      Color(0xff4b0082),
      Color(0xffee82ee),
    ],
  ),
)

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 BSD-3 license. See LICENSE for details.