QRCode Package

This package is a implementation of QR code encoding in Go. It offers an idiomatic Go implementation of QR code encoding, requires only an golang.org/x/text dependency, maintainable by the Go team.

Features

• all modes (numeric, alphanumeric, byte, kanji, eci)
• Micro QR codes
• export to PNG/JPEG/GIF
• ECI (Extended Channel Interpretation)
• requires only an golang.org/x/text dependency
• covered by unit/functional tests

Installation

go get github.com/verte-zerg/qrcode

Usage

Import

import "github.com/verte-zerg/qrcode"

Create QR code

qr, err := qrcode.Create("https://example.com", nil)
if err != nil {
    panic(err)
}

Plot QR code

file, err := os.Create("qrcode.png")
if err != nil {
    panic(err)
}

defer file.Close()

if err := qr.Plot(file, nil); err != nil {
    fmt.Println(err)
}

Options

The qrcode.Create function accepts an Options struct as a second argument. The Options struct has the following fields:

type QRCodeOptions struct {
	// Encoding is the encoding mode.
	// Default: calculated based on the content (numeric, alphanumeric, byte, kanji or utf-8 with ECI)
	Mode encode.EncodingMode

	// Level is the error correction level.
	// Default: ErrorCorrectionLevelLow.
	ErrorLevel ErrorCorrectionLevel

	// Version is the version of the QR Code.
	// Default: calculated based on the content.
	Version int

	// Enable micro QR code
	// Default: false
	MicroQR bool
}

You can specify the encoding mode, error correction level, version and enable micro QR code.

Supported encoding modes:

• encode.EncodingModeNumeric
• encode.EncodingModeAlphanumeric
• encode.EncodingModeByte
• encode.EncodingModeKanji
• encode.EncodingModeECI

Supported error correction levels:

• ErrorCorrectionLevelLow
• ErrorCorrectionLevelMedium
• ErrorCorrectionLevelQuartile
• ErrorCorrectionLevelHigh

If Micro QR code is enabled, the version must be between M1 and M4. Micro QR code version constants:

• M1 (-1)
• M2 (-2)
• M3 (-3)
• M4 (-4)

If you want to use specific ECI mode, you can use qrcode.CreateMultiMode function. The function can build QR code with several blocks of data with different modes.

import (
    "github.com/verte-zerg/qrcode"
    "github.com/verte-zerg/qrcode/encode"
)

func main() {
	encodeBlocks := []*encode.EncodeBlock{
		{
			Mode: encode.EncodingModeNumeric,
			Data: "1234567890",
		},
		{
			Mode:             encode.EncodingModeECI,
			Data:             "привет мир",
			SubMode:          encode.EncodingModeByte,  // The mode must be always equal to EncodingModeByte for ECI
			AssignmentNumber: encode.ISO8859_5, // cyrillic
		},
	}

	qr, err := CreateMultiMode(encodeBlocks, nil)
	if err != nil {
		panic(err)
	}

	file, err := os.Create("qrcode_mix.png")
	if err != nil {
		panic(err)
	}

	defer file.Close()

	if err := qr.Plot(file, nil); err != nil {
		panic(err)
	}
}

The list of supported ECI assignments can be found in the encode package.

You can specify several plot options using the PlotOptions struct:

type PlotOptions struct {
	// Scale is the scale for the QR Code image (in pixels).
	// The image will be len(data) * Scale x len(data) * Scale pixels.
	// Default: 4.
	Scale int

	// Border is the border for the QR Code image (in pixels).
	// Default: 0.
	Border int

	// OutputFormat is the format of the output image.
	// Default: PNG.
	OutputFormat OutputFormat
}

Supported output formats:

• PNG
• JPEG
• GIF

Functions

Create(content string, options *QRCodeOptions) (*QRCode, error) - creates a QR code with the specified content and options. CreateMultiMode(blocks []*encode.EncodeBlock, options *QRCodeOptionsMultiMode) (*QRCode, error) - creates a QR code with the specified blocks of data and options. (qr *QRCode) Plot(writer io.Writer, options *PlotOptions) error - plots the QR code with the specified options to the writer.

Roadmap

Features

• add predefined QR code types (vCard, WiFi, etc.)
• support other image formats (JPEG, GIF, etc.)
• data optimization algorithm
• custom data encoding
• structured append codes
• custom colors
• different shapes for the markers
• support adding a logo to the QR code

License

This package is licensed under the MIT License. See the LICENSE file for details.

Contributing

If you find a bug or want to contribute to the code or documentation, you can help by submitting an issue or a pull request.