qr_code_vision 0.0.1

A pure Dart package for QR detection, decoding and tracking.

This package provides both high-level and low-level functions to extract QR code data from an image, including its location, type and content. In addition, it can be used to efficiently track a QR code position between frames, that can be used for AR (Augmented Reality) applications in Flutter. qr_code_vision is written in pure Dart, and is based on the popular jsQR javascript QR reader.

Features

https://user-images.githubusercontent.com/54476193/150672495-f2def04c-5e60-4531-9c49-e2dfc72bab7b.mp4

This package is still in early development, and most features are not implemented yet. Currently, you will be able to only locate a QR code in an image, extracting the position of its finder patterns and alignment pattern. This information already allows to build basic AR applications like the one in the example.

Decoding the QR code content and handling multiple QR codes in a single image is not yet implemented.

Usage

In order to locate a QR code in an image, you need to first obtain a binary version, represented by a BitMatrix object. You can use the convertToBinary() function to turn any RGBA byte list (obtained from a dart:ui Image object for example) into a BitMatrix.

// Let `image` be a `dart:ui` `Image` object
final BitMatrix bitMatrix = convertToBinary(image.toByteData());

In order to search and extract a QR location from the image, use the locate() method of the QrLocator class.

final QrLocator locator = QrLocator();
final QrLocation location = locator.locate(bitMatrix);

if(location == null){
    print('No QR code found');
}else{
    print('QR code indentified!');
    print('- Top-left finder pattern: ${location.topLeft}');
    print('- Top-right finder pattern: ${location.topRight}');
    print('- Bottom-left finder pattern: ${location.bottomLeft}');
    print('- Alignment pattern: ${location.alignmentPattern}');
}

Location information can then be used to compute the QR code 4x4 transformation matrix (at this time, only affine transformation is supported, based on the finder patterns). Such matrix can be used to easily draw AR content over the QR code in a Flutter application. Refer to the example for more details.