package coding

import "rsc.io/qr/coding"

Package coding implements low-level QR coding details.

Index ¶

• Constants
• Variables
• type Alpha
• func (s Alpha) Bits(v Version) int
• func (s Alpha) Check() error
• func (s Alpha) Encode(b *Bits, v Version)
• func (s Alpha) String() string
• type Bits
• func (b *Bits) AddCheckBytes(v Version, l Level)
• func (b *Bits) Append(p []byte)
• func (b *Bits) Bits() int
• func (b *Bits) Bytes() []byte
• func (b *Bits) Pad(n int)
• func (b *Bits) Reset()
• func (b *Bits) Write(v uint, nbit int)
• type Code
• func (c *Code) Black(x, y int) bool
• type Encoding
• type Level
• func (l Level) String() string
• type Mask
• func (m Mask) Invert(y, x int) bool
• type Num
• func (s Num) Bits(v Version) int
• func (s Num) Check() error
• func (s Num) Encode(b *Bits, v Version)
• func (s Num) String() string
• type Pixel
• func OffsetPixel(o uint) Pixel
• func (p Pixel) Offset() uint
• func (p Pixel) Role() PixelRole
• func (p Pixel) String() string
• type PixelRole
• func (r PixelRole) Pixel() Pixel
• func (r PixelRole) String() string
• type Plan
• func NewPlan(version Version, level Level, mask Mask) (*Plan, error)
• func (p *Plan) Encode(text ...Encoding) (*Code, error)
• type String
• func (s String) Bits(v Version) int
• func (s String) Check() error
• func (s String) Encode(b *Bits, v Version)
• func (s String) String() string
• type Version
• func (v Version) DataBytes(l Level) int
• func (v Version) String() string

Constants ¶

const MaxVersion = 40

const MinVersion = 1

Variables ¶

var Field = gf256.NewField(0x11d, 2)

Field is the field for QR error correction.

Types ¶

type Alpha ¶

type Alpha string

Alpha is the encoding for alphanumeric data. The valid characters are 0-9A-Z$%*+-./: and space.

func (Alpha) Bits ¶

func (s Alpha) Bits(v Version) int

func (Alpha) Check ¶

func (s Alpha) Check() error

func (Alpha) Encode ¶

func (s Alpha) Encode(b *Bits, v Version)

func (Alpha) String ¶

func (s Alpha) String() string

type Bits ¶

type Bits struct {
	// contains filtered or unexported fields
}

func (*Bits) AddCheckBytes ¶

func (b *Bits) AddCheckBytes(v Version, l Level)

func (*Bits) Append ¶

func (b *Bits) Append(p []byte)

func (*Bits) Bits ¶

func (b *Bits) Bits() int

func (*Bits) Bytes ¶

func (b *Bits) Bytes() []byte

func (*Bits) Pad ¶

func (b *Bits) Pad(n int)

func (*Bits) Reset ¶

func (b *Bits) Reset()

func (*Bits) Write ¶

func (b *Bits) Write(v uint, nbit int)

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
}

A Code is a square pixel grid.

func (*Code) Black ¶

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

type Encoding ¶

type Encoding interface {
	Check() error
	Bits(v Version) int
	Encode(b *Bits, v Version)
}

Encoding implements a QR data encoding scheme. The implementations--Numeric, Alphanumeric, and String--specify the character set and the mapping from UTF-8 to code bits. The more restrictive the mode, the fewer code bits are needed.

type Level ¶

type Level int

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

const (
	L Level = iota
	M
	Q
	H
)

func (Level) String ¶

func (l Level) String() string

type Mask ¶

type Mask int

A Mask describes a mask that is applied to the QR code to avoid QR artifacts being interpreted as alignment and timing patterns (such as the squares in the corners). Valid masks are integers from 0 to 7.

func (Mask) Invert ¶

func (m Mask) Invert(y, x int) bool

type Num ¶

type Num string

Num is the encoding for numeric data. The only valid characters are the decimal digits 0 through 9.

func (Num) Bits ¶

func (s Num) Bits(v Version) int

func (Num) Check ¶

func (s Num) Check() error

func (Num) Encode ¶

func (s Num) Encode(b *Bits, v Version)

func (Num) String ¶

func (s Num) String() string

type Pixel ¶

type Pixel uint32

A Pixel describes a single pixel in a QR code.

const (
	Black Pixel = 1 << iota
	Invert
)

func OffsetPixel ¶

func OffsetPixel(o uint) Pixel

func (Pixel) Offset ¶

func (p Pixel) Offset() uint

func (Pixel) Role ¶

func (p Pixel) Role() PixelRole

func (Pixel) String ¶

func (p Pixel) String() string

type PixelRole ¶

type PixelRole uint32

A PixelRole describes the role of a QR pixel.

const (
	Position  PixelRole // position squares (large)
	Alignment           // alignment squares (small)
	Timing              // timing strip between position squares
	Format              // format metadata
	PVersion            // version pattern
	Unused              // unused pixel
	Data                // data bit
	Check               // error correction check bit
	Extra
)

func (PixelRole) Pixel ¶

func (r PixelRole) Pixel() Pixel

func (PixelRole) String ¶

func (r PixelRole) String() string

type Plan ¶

type Plan struct {
	Version Version
	Level   Level
	Mask    Mask

	DataBytes  int // number of data bytes
	CheckBytes int // number of error correcting (checksum) bytes
	Blocks     int // number of data blocks

	Pixel [][]Pixel // pixel map
}

A Plan describes how to construct a QR code with a specific version, level, and mask.

func NewPlan ¶

func NewPlan(version Version, level Level, mask Mask) (*Plan, error)

NewPlan returns a Plan for a QR code with the given version, level, and mask.

func (*Plan) Encode ¶

func (p *Plan) Encode(text ...Encoding) (*Code, error)

type String ¶

type String string

String is the encoding for 8-bit data. All bytes are valid.

func (String) Bits ¶

func (s String) Bits(v Version) int

func (String) Check ¶

func (s String) Check() error

func (String) Encode ¶

func (s String) Encode(b *Bits, v Version)

func (String) String ¶

func (s String) String() string

type Version ¶

type Version int

A Version represents a QR version. The version specifies the size of the QR code: a QR code with version v has 4v+17 pixels on a side. Versions number from 1 to 40: the larger the version, the more information the code can store.

func (Version) DataBytes ¶

func (v Version) DataBytes(l Level) int

DataBytes returns the number of data bytes that can be stored in a QR code with the given version and level.

func (Version) String ¶

func (v Version) String() string

Source Files ¶

qr.go