package qr

import "rsc.io/qr"

Package qr encodes QR codes.

Index ¶

• type Code
• func Encode(text string, level Level) (*Code, error)
• func (c *Code) Black(x, y int) bool
• func (c *Code) Image() image.Image
• func (c *Code) PNG() []byte
• type Level

Types ¶

type Code ¶

type Code struct {
	Bitmap []byte // 1 is black, 0 is white
	Size   int    // number of pixels on a side
	Stride int    // number of bytes per row
	Scale  int    // number of image pixels per QR pixel
}

A Code is a square pixel grid. It implements image.Image and direct PNG encoding.

func Encode ¶

func Encode(text string, level Level) (*Code, error)

Encode returns an encoding of text at the given error correction level.

func (*Code) Black ¶

func (c *Code) Black(x, y int) bool

Black returns true if the pixel at (x,y) is black.

func (*Code) Image ¶

func (c *Code) Image() image.Image

Image returns an Image displaying the code.

func (*Code) PNG ¶

func (c *Code) PNG() []byte

PNG returns a PNG image displaying the code.

PNG uses a custom encoder tailored to QR codes. Its compressed size is about 2x away from optimal, but it runs about 20x faster than calling png.Encode on c.Image().

type Level ¶

type Level int

A Level denotes a QR error correction level. From least to most tolerant of errors, they are L, M, Q, H.

const (
	L Level = iota // 20% redundant
	M              // 38% redundant
	Q              // 55% redundant
	H              // 65% redundant
)

Source Files ¶

png.go qr.go

Directories ¶