qrcode

package module
Version: v0.0.0-...-3976bd1 Latest Latest
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Published: Aug 27, 2020 License: MIT Imports: 11 Imported by: 1

README

go-qrcode

Package qrcode implements a QR Code encoder. Build Status

A QR Code is a matrix (two-dimensional) barcode. Arbitrary content may be encoded, with URLs being a popular choice :)

Each QR Code contains error recovery information to aid reading damaged or obscured codes. There are four levels of error recovery: Low, medium, high and highest. QR Codes with a higher recovery level are more robust to damage, at the cost of being physically larger.

Install

go get -u github.com/buzzxu/go-qrcode/...

A command-line tool qrcode will be built into $GOPATH/bin/.

Usage

import qrcode "github.com/buzzxu/go-qrcode"
  • Create a PNG image:

      var png []byte
      png, err := qrcode.Encode("https://example.org", qrcode.Medium, 256)
    
  • Create a PNG image and write to a file:

      err := qrcode.WriteFile("https://example.org", qrcode.Medium, 256, "qr.png")
    

Both examples use the qrcode.Medium error Recovery Level and create a 256x256 pixel, black on white QR Code.

The maximum capacity of a QR Code varies according to the content encoded and the error recovery level. The maximum capacity is 2,953 bytes, 4,296 alphanumeric characters, 7,089 numeric digits, or a combination of these.

Documentation

godoc

Demoapp

http://go-qrcode.appspot.com

CLI

A command-line tool qrcode will be built into $GOPATH/bin/.

qrcode -- QR Code encoder in Go
https://github.com/buzzxu/go-qrcode

Flags:
  -o string
        out PNG file prefix, empty for stdout
  -s int
        image size (pixel) (default 256)

Usage:
  1. Arguments except for flags are joined by " " and used to generate QR code.
     Default output is STDOUT, pipe to imagemagick command "display" to display
     on any X server.

       qrcode hello word | display

  2. Save to file if "display" not available:

       qrcode "homepage: https://github.com/buzzxu/go-qrcode" > out.png

Documentation

Overview

Package qrcode implements a QR Code encoder.

A QR Code is a matrix (two-dimensional) barcode. Arbitrary content may be encoded.

A QR Code contains error recovery information to aid reading damaged or obscured codes. There are four levels of error recovery: qrcode.{Low, Medium, High, Highest}. QR Codes with a higher recovery level are more robust to damage, at the cost of being physically larger.

Two functions cover most use cases:

- Create a PNG image:

var png []byte
png, err := qrcode.Encode("https://example.org", qrcode.Medium, 256)

- Create a PNG image and write to a file:

err := qrcode.WriteFile("https://example.org", qrcode.Medium, 256, "qr.png")

Both examples use the qrcode.Medium error Recovery Level and create a 256x256 pixel, black on white QR Code.

The maximum capacity of a QR Code varies according to the content encoded and the error recovery level. The maximum capacity is 2,953 bytes, 4,296 alphanumeric characters, 7,089 numeric digits, or a combination of these.

This package implements a subset of QR Code 2005, as defined in ISO/IEC 18004:2006.

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func Encode

func Encode(content string, level RecoveryLevel, size int) ([]byte, error)

Encode a QR Code and return a raw PNG image.

size is both the image width and height in pixels. If size is too small then a larger image is silently returned.

To serve over HTTP, remember to send a Content-Type: image/png header.

Example
var png []byte
png, err := Encode("https://example.org", Medium, 256)

if err != nil {
	fmt.Printf("Error: %s", err.Error())
} else {
	fmt.Printf("PNG is %d bytes long", len(png))
}
Output:

func WriteFile

func WriteFile(content string, level RecoveryLevel, size int, filename string) error

WriteFile encodes, then writes a QR Code to the given filename in PNG format.

size is both the width and height in pixels. If size is too small then a larger image is silently written.

Example
filename := "example.png"

err := WriteFile("https://example.org", Medium, 256, filename)

if err != nil {
	err = os.Remove(filename)
}

if err != nil {
	fmt.Printf("Error: %s", err.Error())
}
Output:

Types

type QRCode

type QRCode struct {
	// Original content encoded.
	Content string

	// QR Code type.
	Level         RecoveryLevel
	VersionNumber int

	// User settable drawing options.
	ForegroundColor color.Color
	BackgroundColor color.Color
	// contains filtered or unexported fields
}

A QRCode represents a valid encoded QRCode.

func New

func New(content string, level RecoveryLevel) (*QRCode, error)

New constructs a QRCode.

var q *qrcode.QRCode
q, err := qrcode.New("my content", qrcode.Medium)

An error occurs if the content is too long.

func NewWithColor

func NewWithColor(content string, level RecoveryLevel, bg, fore color.Color) (*QRCode, error)

@2017.4.7 by kolonse for control color of bg and fore

func (*QRCode) Bitmap

func (q *QRCode) Bitmap() [][]bool

Bitmap returns the QR Code as a 2D array of 1-bit pixels.

bitmap[y][x] is true if the pixel at (x, y) is set.

The bitmap includes the required "quiet zone" around the QR Code to aid decoding.

func (*QRCode) Image

func (q *QRCode) Image(size int) image.Image

Image returns the QR Code as an image.Image.

size is both the width and height in pixels.

func (*QRCode) ImageWithBorderMaxSize

func (q *QRCode) ImageWithBorderMaxSize(size int, borderMaxSize int) image.Image

size is both the width and height in pixels.

func (*QRCode) PNG

func (q *QRCode) PNG(size int) ([]byte, error)

PNG returns the QR Code as a PNG image.

size is both the image width and height in pixels. If size is too small then a larger image is silently returned.

func (*QRCode) Write

func (q *QRCode) Write(size int, out io.Writer) error

Write writes the QR Code as a PNG image to io.Writer.

size is both the image width and height in pixels. If size is too small then a larger image is silently written.

func (*QRCode) WriteFile

func (q *QRCode) WriteFile(size int, filename string) error

WriteFile writes the QR Code as a PNG image to the specified file.

size is both the image width and height in pixels. If size is too small then a larger image is silently written.

type RecoveryLevel

type RecoveryLevel int

Error detection/recovery capacity.

There are several levels of error detection/recovery capacity. Higher levels of error recovery are able to correct more errors, with the trade-off of increased symbol size.

const (
	// Level L: 7% error recovery.
	Low RecoveryLevel = iota

	// Level M: 15% error recovery. Good default choice.
	Medium

	// Level Q: 25% error recovery.
	High

	// Level H: 30% error recovery.
	Highest
)

Directories

Path Synopsis
Package bitset implements an append only bit array.
Package bitset implements an append only bit array.
Package reedsolomon provides error correction encoding for QR Code 2005.
Package reedsolomon provides error correction encoding for QR Code 2005.

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