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Tulir Asokan
554
vendor/github.com/skip2/go-qrcode/qrcode.go
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vendored
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554
vendor/github.com/skip2/go-qrcode/qrcode.go
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@ -0,0 +1,554 @@
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// go-qrcode
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// Copyright 2014 Tom Harwood
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/*
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Package qrcode implements a QR Code encoder.
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A QR Code is a matrix (two-dimensional) barcode. Arbitrary content may be
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encoded.
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A QR Code contains error recovery information to aid reading damaged or
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obscured codes. There are four levels of error recovery: qrcode.{Low, Medium,
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High, Highest}. QR Codes with a higher recovery level are more robust to damage,
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at the cost of being physically larger.
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Three functions cover most use cases:
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- Create a PNG image:
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var png []byte
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png, err := qrcode.Encode("https://example.org", qrcode.Medium, 256)
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- Create a PNG image and write to a file:
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err := qrcode.WriteFile("https://example.org", qrcode.Medium, 256, "qr.png")
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- Create a PNG image with custom colors and write to file:
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err := qrcode.WriteColorFile("https://example.org", qrcode.Medium, 256, color.Black, color.White, "qr.png")
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All examples use the qrcode.Medium error Recovery Level and create a fixed
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256x256px size QR Code. The last function creates a white on black instead of black
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on white QR Code.
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To generate a variable sized image instead, specify a negative size (in place of
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the 256 above), such as -4 or -5. Larger negative numbers create larger images:
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A size of -5 sets each module (QR Code "pixel") to be 5px wide/high.
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- Create a PNG image (variable size, with minimum white padding) and write to a file:
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err := qrcode.WriteFile("https://example.org", qrcode.Medium, -5, "qr.png")
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The maximum capacity of a QR Code varies according to the content encoded and
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the error recovery level. The maximum capacity is 2,953 bytes, 4,296
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alphanumeric characters, 7,089 numeric digits, or a combination of these.
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This package implements a subset of QR Code 2005, as defined in ISO/IEC
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18004:2006.
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*/
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package qrcode
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import (
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"bytes"
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"errors"
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"image"
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"image/color"
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"image/png"
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"io"
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"io/ioutil"
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"log"
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"os"
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bitset "github.com/skip2/go-qrcode/bitset"
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reedsolomon "github.com/skip2/go-qrcode/reedsolomon"
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)
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// Encode a QR Code and return a raw PNG image.
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//
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// size is both the image width and height in pixels. If size is too small then
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// a larger image is silently returned. Negative values for size cause a
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// variable sized image to be returned: See the documentation for Image().
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//
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// To serve over HTTP, remember to send a Content-Type: image/png header.
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func Encode(content string, level RecoveryLevel, size int) ([]byte, error) {
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var q *QRCode
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q, err := New(content, level)
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if err != nil {
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return nil, err
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}
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return q.PNG(size)
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}
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// WriteFile encodes, then writes a QR Code to the given filename in PNG format.
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//
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// size is both the image width and height in pixels. If size is too small then
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// a larger image is silently written. Negative values for size cause a variable
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// sized image to be written: See the documentation for Image().
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func WriteFile(content string, level RecoveryLevel, size int, filename string) error {
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var q *QRCode
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q, err := New(content, level)
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if err != nil {
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return err
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}
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return q.WriteFile(size, filename)
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}
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// WriteColorFile encodes, then writes a QR Code to the given filename in PNG format.
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// With WriteColorFile you can also specify the colors you want to use.
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//
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// size is both the image width and height in pixels. If size is too small then
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// a larger image is silently written. Negative values for size cause a variable
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// sized image to be written: See the documentation for Image().
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func WriteColorFile(content string, level RecoveryLevel, size int, background,
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foreground color.Color, filename string) error {
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var q *QRCode
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q, err := New(content, level)
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q.BackgroundColor = background
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q.ForegroundColor = foreground
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if err != nil {
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return err
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}
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return q.WriteFile(size, filename)
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}
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// A QRCode represents a valid encoded QRCode.
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type QRCode struct {
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// Original content encoded.
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Content string
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// QR Code type.
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Level RecoveryLevel
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VersionNumber int
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// User settable drawing options.
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ForegroundColor color.Color
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BackgroundColor color.Color
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encoder *dataEncoder
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version qrCodeVersion
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data *bitset.Bitset
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symbol *symbol
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mask int
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}
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// New constructs a QRCode.
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//
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// var q *qrcode.QRCode
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// q, err := qrcode.New("my content", qrcode.Medium)
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//
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// An error occurs if the content is too long.
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func New(content string, level RecoveryLevel) (*QRCode, error) {
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encoders := []dataEncoderType{dataEncoderType1To9, dataEncoderType10To26,
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dataEncoderType27To40}
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var encoder *dataEncoder
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var encoded *bitset.Bitset
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var chosenVersion *qrCodeVersion
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var err error
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for _, t := range encoders {
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encoder = newDataEncoder(t)
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encoded, err = encoder.encode([]byte(content))
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if err != nil {
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continue
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}
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chosenVersion = chooseQRCodeVersion(level, encoder, encoded.Len())
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if chosenVersion != nil {
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break
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}
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}
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if err != nil {
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return nil, err
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} else if chosenVersion == nil {
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return nil, errors.New("content too long to encode")
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}
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q := &QRCode{
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Content: content,
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Level: level,
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VersionNumber: chosenVersion.version,
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ForegroundColor: color.Black,
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BackgroundColor: color.White,
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encoder: encoder,
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data: encoded,
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version: *chosenVersion,
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}
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q.encode(chosenVersion.numTerminatorBitsRequired(encoded.Len()))
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return q, nil
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}
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func newWithForcedVersion(content string, version int, level RecoveryLevel) (*QRCode, error) {
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var encoder *dataEncoder
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switch {
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case version >= 1 && version <= 9:
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encoder = newDataEncoder(dataEncoderType1To9)
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case version >= 10 && version <= 26:
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encoder = newDataEncoder(dataEncoderType10To26)
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case version >= 27 && version <= 40:
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encoder = newDataEncoder(dataEncoderType27To40)
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default:
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log.Fatalf("Invalid version %d (expected 1-40 inclusive)", version)
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}
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var encoded *bitset.Bitset
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encoded, err := encoder.encode([]byte(content))
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if err != nil {
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return nil, err
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}
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chosenVersion := getQRCodeVersion(level, version)
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if chosenVersion == nil {
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return nil, errors.New("cannot find QR Code version")
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}
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q := &QRCode{
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Content: content,
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Level: level,
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VersionNumber: chosenVersion.version,
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ForegroundColor: color.Black,
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BackgroundColor: color.White,
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encoder: encoder,
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data: encoded,
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version: *chosenVersion,
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}
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q.encode(chosenVersion.numTerminatorBitsRequired(encoded.Len()))
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return q, nil
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}
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// Bitmap returns the QR Code as a 2D array of 1-bit pixels.
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//
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// bitmap[y][x] is true if the pixel at (x, y) is set.
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//
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// The bitmap includes the required "quiet zone" around the QR Code to aid
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// decoding.
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func (q *QRCode) Bitmap() [][]bool {
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return q.symbol.bitmap()
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}
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// Image returns the QR Code as an image.Image.
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//
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// A positive size sets a fixed image width and height (e.g. 256 yields an
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// 256x256px image).
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//
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// Depending on the amount of data encoded, fixed size images can have different
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// amounts of padding (white space around the QR Code). As an alternative, a
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// variable sized image can be generated instead:
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//
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// A negative size causes a variable sized image to be returned. The image
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// returned is the minimum size required for the QR Code. Choose a larger
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// negative number to increase the scale of the image. e.g. a size of -5 causes
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// each module (QR Code "pixel") to be 5px in size.
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func (q *QRCode) Image(size int) image.Image {
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// Minimum pixels (both width and height) required.
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realSize := q.symbol.size
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// Variable size support.
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if size < 0 {
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size = size * -1 * realSize
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}
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// Actual pixels available to draw the symbol. Automatically increase the
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// image size if it's not large enough.
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if size < realSize {
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size = realSize
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}
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// Size of each module drawn.
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pixelsPerModule := size / realSize
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// Center the symbol within the image.
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offset := (size - realSize*pixelsPerModule) / 2
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rect := image.Rectangle{Min: image.Point{0, 0}, Max: image.Point{size, size}}
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// Saves a few bytes to have them in this order
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p := color.Palette([]color.Color{q.BackgroundColor, q.ForegroundColor})
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img := image.NewPaletted(rect, p)
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for i := 0; i < size; i++ {
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for j := 0; j < size; j++ {
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img.Set(i, j, q.BackgroundColor)
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}
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}
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bitmap := q.symbol.bitmap()
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for y, row := range bitmap {
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for x, v := range row {
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if v {
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startX := x*pixelsPerModule + offset
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startY := y*pixelsPerModule + offset
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for i := startX; i < startX+pixelsPerModule; i++ {
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for j := startY; j < startY+pixelsPerModule; j++ {
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img.Set(i, j, q.ForegroundColor)
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}
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}
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}
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}
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}
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return img
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}
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// PNG returns the QR Code as a PNG image.
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//
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// size is both the image width and height in pixels. If size is too small then
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// a larger image is silently returned. Negative values for size cause a
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// variable sized image to be returned: See the documentation for Image().
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func (q *QRCode) PNG(size int) ([]byte, error) {
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img := q.Image(size)
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encoder := png.Encoder{CompressionLevel: png.BestCompression}
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var b bytes.Buffer
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err := encoder.Encode(&b, img)
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if err != nil {
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return nil, err
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}
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return b.Bytes(), nil
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}
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// Write writes the QR Code as a PNG image to io.Writer.
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//
|
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// size is both the image width and height in pixels. If size is too small then
|
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// a larger image is silently written. Negative values for size cause a
|
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// variable sized image to be written: See the documentation for Image().
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func (q *QRCode) Write(size int, out io.Writer) error {
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var png []byte
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png, err := q.PNG(size)
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if err != nil {
|
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return err
|
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}
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_, err = out.Write(png)
|
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return err
|
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}
|
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|
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// WriteFile writes the QR Code as a PNG image to the specified file.
|
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//
|
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// size is both the image width and height in pixels. If size is too small then
|
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// a larger image is silently written. Negative values for size cause a
|
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// variable sized image to be written: See the documentation for Image().
|
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func (q *QRCode) WriteFile(size int, filename string) error {
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var png []byte
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png, err := q.PNG(size)
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|
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if err != nil {
|
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return err
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}
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return ioutil.WriteFile(filename, png, os.FileMode(0644))
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}
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// encode completes the steps required to encode the QR Code. These include
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// adding the terminator bits and padding, splitting the data into blocks and
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// applying the error correction, and selecting the best data mask.
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func (q *QRCode) encode(numTerminatorBits int) {
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q.addTerminatorBits(numTerminatorBits)
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q.addPadding()
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encoded := q.encodeBlocks()
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const numMasks int = 8
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penalty := 0
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for mask := 0; mask < numMasks; mask++ {
|
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var s *symbol
|
||||
var err error
|
||||
|
||||
s, err = buildRegularSymbol(q.version, mask, encoded)
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||||
|
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if err != nil {
|
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log.Panic(err.Error())
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}
|
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|
||||
numEmptyModules := s.numEmptyModules()
|
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if numEmptyModules != 0 {
|
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log.Panicf("bug: numEmptyModules is %d (expected 0) (version=%d)",
|
||||
numEmptyModules, q.VersionNumber)
|
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}
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p := s.penaltyScore()
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//log.Printf("mask=%d p=%3d p1=%3d p2=%3d p3=%3d p4=%d\n", mask, p, s.penalty1(), s.penalty2(), s.penalty3(), s.penalty4())
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|
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if q.symbol == nil || p < penalty {
|
||||
q.symbol = s
|
||||
q.mask = mask
|
||||
penalty = p
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// addTerminatorBits adds final terminator bits to the encoded data.
|
||||
//
|
||||
// The number of terminator bits required is determined when the QR Code version
|
||||
// is chosen (which itself depends on the length of the data encoded). The
|
||||
// terminator bits are thus added after the QR Code version
|
||||
// is chosen, rather than at the data encoding stage.
|
||||
func (q *QRCode) addTerminatorBits(numTerminatorBits int) {
|
||||
q.data.AppendNumBools(numTerminatorBits, false)
|
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}
|
||||
|
||||
// encodeBlocks takes the completed (terminated & padded) encoded data, splits
|
||||
// the data into blocks (as specified by the QR Code version), applies error
|
||||
// correction to each block, then interleaves the blocks together.
|
||||
//
|
||||
// The QR Code's final data sequence is returned.
|
||||
func (q *QRCode) encodeBlocks() *bitset.Bitset {
|
||||
// Split into blocks.
|
||||
type dataBlock struct {
|
||||
data *bitset.Bitset
|
||||
ecStartOffset int
|
||||
}
|
||||
|
||||
block := make([]dataBlock, q.version.numBlocks())
|
||||
|
||||
start := 0
|
||||
end := 0
|
||||
blockID := 0
|
||||
|
||||
for _, b := range q.version.block {
|
||||
for j := 0; j < b.numBlocks; j++ {
|
||||
start = end
|
||||
end = start + b.numDataCodewords*8
|
||||
|
||||
// Apply error correction to each block.
|
||||
numErrorCodewords := b.numCodewords - b.numDataCodewords
|
||||
block[blockID].data = reedsolomon.Encode(q.data.Substr(start, end), numErrorCodewords)
|
||||
block[blockID].ecStartOffset = end - start
|
||||
|
||||
blockID++
|
||||
}
|
||||
}
|
||||
|
||||
// Interleave the blocks.
|
||||
|
||||
result := bitset.New()
|
||||
|
||||
// Combine data blocks.
|
||||
working := true
|
||||
for i := 0; working; i += 8 {
|
||||
working = false
|
||||
|
||||
for j, b := range block {
|
||||
if i >= block[j].ecStartOffset {
|
||||
continue
|
||||
}
|
||||
|
||||
result.Append(b.data.Substr(i, i+8))
|
||||
|
||||
working = true
|
||||
}
|
||||
}
|
||||
|
||||
// Combine error correction blocks.
|
||||
working = true
|
||||
for i := 0; working; i += 8 {
|
||||
working = false
|
||||
|
||||
for j, b := range block {
|
||||
offset := i + block[j].ecStartOffset
|
||||
if offset >= block[j].data.Len() {
|
||||
continue
|
||||
}
|
||||
|
||||
result.Append(b.data.Substr(offset, offset+8))
|
||||
|
||||
working = true
|
||||
}
|
||||
}
|
||||
|
||||
// Append remainder bits.
|
||||
result.AppendNumBools(q.version.numRemainderBits, false)
|
||||
|
||||
return result
|
||||
}
|
||||
|
||||
// max returns the maximum of a and b.
|
||||
func max(a int, b int) int {
|
||||
if a > b {
|
||||
return a
|
||||
}
|
||||
|
||||
return b
|
||||
}
|
||||
|
||||
// addPadding pads the encoded data upto the full length required.
|
||||
func (q *QRCode) addPadding() {
|
||||
numDataBits := q.version.numDataBits()
|
||||
|
||||
if q.data.Len() == numDataBits {
|
||||
return
|
||||
}
|
||||
|
||||
// Pad to the nearest codeword boundary.
|
||||
q.data.AppendNumBools(q.version.numBitsToPadToCodeword(q.data.Len()), false)
|
||||
|
||||
// Pad codewords 0b11101100 and 0b00010001.
|
||||
padding := [2]*bitset.Bitset{
|
||||
bitset.New(true, true, true, false, true, true, false, false),
|
||||
bitset.New(false, false, false, true, false, false, false, true),
|
||||
}
|
||||
|
||||
// Insert pad codewords alternately.
|
||||
i := 0
|
||||
for numDataBits-q.data.Len() >= 8 {
|
||||
q.data.Append(padding[i])
|
||||
|
||||
i = 1 - i // Alternate between 0 and 1.
|
||||
}
|
||||
|
||||
if q.data.Len() != numDataBits {
|
||||
log.Panicf("BUG: got len %d, expected %d", q.data.Len(), numDataBits)
|
||||
}
|
||||
}
|
||||
|
||||
// ToString produces a multi-line string that forms a QR-code image.
|
||||
func (q *QRCode) ToString(inverseColor bool) string {
|
||||
bits := q.Bitmap()
|
||||
var buf bytes.Buffer
|
||||
for y := range bits {
|
||||
for x := range bits[y] {
|
||||
if bits[y][x] != inverseColor {
|
||||
buf.WriteString(" ")
|
||||
} else {
|
||||
buf.WriteString("██")
|
||||
}
|
||||
}
|
||||
buf.WriteString("\n")
|
||||
}
|
||||
return buf.String()
|
||||
}
|
||||
Reference in New Issue
Block a user