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authorWim <wim@42.be>2022-03-20 02:20:54 +0100
committerWim <wim@42.be>2022-03-20 14:57:48 +0100
commit496d5b4ec7f5f4afae6199f928675d14d18de015 (patch)
tree3a649c80a76f0ffc33e6b3a63c0e65e892169cde /vendor/github.com/skip2/go-qrcode/encoder.go
parent2623a412c42a81104b97ae8c81a5f66760fee4b6 (diff)
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Add whatsappmulti buildflag for whatsapp with multidevice support (whatsapp)
Diffstat (limited to 'vendor/github.com/skip2/go-qrcode/encoder.go')
-rw-r--r--vendor/github.com/skip2/go-qrcode/encoder.go455
1 files changed, 455 insertions, 0 deletions
diff --git a/vendor/github.com/skip2/go-qrcode/encoder.go b/vendor/github.com/skip2/go-qrcode/encoder.go
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+// go-qrcode
+// Copyright 2014 Tom Harwood
+
+package qrcode
+
+import (
+ "errors"
+ "log"
+
+ bitset "github.com/skip2/go-qrcode/bitset"
+)
+
+// Data encoding.
+//
+// The main data portion of a QR Code consists of one or more segments of data.
+// A segment consists of:
+//
+// - The segment Data Mode: numeric, alphanumeric, or byte.
+// - The length of segment in bits.
+// - Encoded data.
+//
+// For example, the string "123ZZ#!#!" may be represented as:
+//
+// [numeric, 3, "123"] [alphanumeric, 2, "ZZ"] [byte, 4, "#!#!"]
+//
+// Multiple data modes exist to minimise the size of encoded data. For example,
+// 8-bit bytes require 8 bits to encode each, but base 10 numeric data can be
+// encoded at a higher density of 3 numbers (e.g. 123) per 10 bits.
+//
+// Some data can be represented in multiple modes. Numeric data can be
+// represented in all three modes, whereas alphanumeric data (e.g. 'A') can be
+// represented in alphanumeric and byte mode.
+//
+// Starting a new segment (to use a different Data Mode) has a cost, the bits to
+// state the new segment Data Mode and length. To minimise each QR Code's symbol
+// size, an optimisation routine coalesces segment types where possible, to
+// reduce the encoded data length.
+//
+// There are several other data modes available (e.g. Kanji mode) which are not
+// implemented here.
+
+// A segment encoding mode.
+type dataMode uint8
+
+const (
+ // Each dataMode is a subset of the subsequent dataMode:
+ // dataModeNone < dataModeNumeric < dataModeAlphanumeric < dataModeByte
+ //
+ // This ordering is important for determining which data modes a character can
+ // be encoded with. E.g. 'E' can be encoded in both dataModeAlphanumeric and
+ // dataModeByte.
+ dataModeNone dataMode = 1 << iota
+ dataModeNumeric
+ dataModeAlphanumeric
+ dataModeByte
+)
+
+// dataModeString returns d as a short printable string.
+func dataModeString(d dataMode) string {
+ switch d {
+ case dataModeNone:
+ return "none"
+ case dataModeNumeric:
+ return "numeric"
+ case dataModeAlphanumeric:
+ return "alphanumeric"
+ case dataModeByte:
+ return "byte"
+ }
+
+ return "unknown"
+}
+
+type dataEncoderType uint8
+
+const (
+ dataEncoderType1To9 dataEncoderType = iota
+ dataEncoderType10To26
+ dataEncoderType27To40
+)
+
+// segment is a single segment of data.
+type segment struct {
+ // Data Mode (e.g. numeric).
+ dataMode dataMode
+
+ // segment data (e.g. "abc").
+ data []byte
+}
+
+// A dataEncoder encodes data for a particular QR Code version.
+type dataEncoder struct {
+ // Minimum & maximum versions supported.
+ minVersion int
+ maxVersion int
+
+ // Mode indicator bit sequences.
+ numericModeIndicator *bitset.Bitset
+ alphanumericModeIndicator *bitset.Bitset
+ byteModeIndicator *bitset.Bitset
+
+ // Character count lengths.
+ numNumericCharCountBits int
+ numAlphanumericCharCountBits int
+ numByteCharCountBits int
+
+ // The raw input data.
+ data []byte
+
+ // The data classified into unoptimised segments.
+ actual []segment
+
+ // The data classified into optimised segments.
+ optimised []segment
+}
+
+// newDataEncoder constructs a dataEncoder.
+func newDataEncoder(t dataEncoderType) *dataEncoder {
+ d := &dataEncoder{}
+
+ switch t {
+ case dataEncoderType1To9:
+ d = &dataEncoder{
+ minVersion: 1,
+ maxVersion: 9,
+ numericModeIndicator: bitset.New(b0, b0, b0, b1),
+ alphanumericModeIndicator: bitset.New(b0, b0, b1, b0),
+ byteModeIndicator: bitset.New(b0, b1, b0, b0),
+ numNumericCharCountBits: 10,
+ numAlphanumericCharCountBits: 9,
+ numByteCharCountBits: 8,
+ }
+ case dataEncoderType10To26:
+ d = &dataEncoder{
+ minVersion: 10,
+ maxVersion: 26,
+ numericModeIndicator: bitset.New(b0, b0, b0, b1),
+ alphanumericModeIndicator: bitset.New(b0, b0, b1, b0),
+ byteModeIndicator: bitset.New(b0, b1, b0, b0),
+ numNumericCharCountBits: 12,
+ numAlphanumericCharCountBits: 11,
+ numByteCharCountBits: 16,
+ }
+ case dataEncoderType27To40:
+ d = &dataEncoder{
+ minVersion: 27,
+ maxVersion: 40,
+ numericModeIndicator: bitset.New(b0, b0, b0, b1),
+ alphanumericModeIndicator: bitset.New(b0, b0, b1, b0),
+ byteModeIndicator: bitset.New(b0, b1, b0, b0),
+ numNumericCharCountBits: 14,
+ numAlphanumericCharCountBits: 13,
+ numByteCharCountBits: 16,
+ }
+ default:
+ log.Panic("Unknown dataEncoderType")
+ }
+
+ return d
+}
+
+// encode data as one or more segments and return the encoded data.
+//
+// The returned data does not include the terminator bit sequence.
+func (d *dataEncoder) encode(data []byte) (*bitset.Bitset, error) {
+ d.data = data
+ d.actual = nil
+ d.optimised = nil
+
+ if len(data) == 0 {
+ return nil, errors.New("no data to encode")
+ }
+
+ // Classify data into unoptimised segments.
+ d.classifyDataModes()
+
+ // Optimise segments.
+ err := d.optimiseDataModes()
+ if err != nil {
+ return nil, err
+ }
+
+ // Encode data.
+ encoded := bitset.New()
+ for _, s := range d.optimised {
+ d.encodeDataRaw(s.data, s.dataMode, encoded)
+ }
+
+ return encoded, nil
+}
+
+// classifyDataModes classifies the raw data into unoptimised segments.
+// e.g. "123ZZ#!#!" =>
+// [numeric, 3, "123"] [alphanumeric, 2, "ZZ"] [byte, 4, "#!#!"].
+func (d *dataEncoder) classifyDataModes() {
+ var start int
+ mode := dataModeNone
+
+ for i, v := range d.data {
+ newMode := dataModeNone
+ switch {
+ case v >= 0x30 && v <= 0x39:
+ newMode = dataModeNumeric
+ case v == 0x20 || v == 0x24 || v == 0x25 || v == 0x2a || v == 0x2b || v ==
+ 0x2d || v == 0x2e || v == 0x2f || v == 0x3a || (v >= 0x41 && v <= 0x5a):
+ newMode = dataModeAlphanumeric
+ default:
+ newMode = dataModeByte
+ }
+
+ if newMode != mode {
+ if i > 0 {
+ d.actual = append(d.actual, segment{dataMode: mode, data: d.data[start:i]})
+
+ start = i
+ }
+
+ mode = newMode
+ }
+ }
+
+ d.actual = append(d.actual, segment{dataMode: mode, data: d.data[start:len(d.data)]})
+}
+
+// optimiseDataModes optimises the list of segments to reduce the overall output
+// encoded data length.
+//
+// The algorithm coalesces adjacent segments. segments are only coalesced when
+// the Data Modes are compatible, and when the coalesced segment has a shorter
+// encoded length than separate segments.
+//
+// Multiple segments may be coalesced. For example a string of alternating
+// alphanumeric/numeric segments ANANANANA can be optimised to just A.
+func (d *dataEncoder) optimiseDataModes() error {
+ for i := 0; i < len(d.actual); {
+ mode := d.actual[i].dataMode
+ numChars := len(d.actual[i].data)
+
+ j := i + 1
+ for j < len(d.actual) {
+ nextNumChars := len(d.actual[j].data)
+ nextMode := d.actual[j].dataMode
+
+ if nextMode > mode {
+ break
+ }
+
+ coalescedLength, err := d.encodedLength(mode, numChars+nextNumChars)
+
+ if err != nil {
+ return err
+ }
+
+ seperateLength1, err := d.encodedLength(mode, numChars)
+
+ if err != nil {
+ return err
+ }
+
+ seperateLength2, err := d.encodedLength(nextMode, nextNumChars)
+
+ if err != nil {
+ return err
+ }
+
+ if coalescedLength < seperateLength1+seperateLength2 {
+ j++
+ numChars += nextNumChars
+ } else {
+ break
+ }
+ }
+
+ optimised := segment{dataMode: mode,
+ data: make([]byte, 0, numChars)}
+
+ for k := i; k < j; k++ {
+ optimised.data = append(optimised.data, d.actual[k].data...)
+ }
+
+ d.optimised = append(d.optimised, optimised)
+
+ i = j
+ }
+
+ return nil
+}
+
+// encodeDataRaw encodes data in dataMode. The encoded data is appended to
+// encoded.
+func (d *dataEncoder) encodeDataRaw(data []byte, dataMode dataMode, encoded *bitset.Bitset) {
+ modeIndicator := d.modeIndicator(dataMode)
+ charCountBits := d.charCountBits(dataMode)
+
+ // Append mode indicator.
+ encoded.Append(modeIndicator)
+
+ // Append character count.
+ encoded.AppendUint32(uint32(len(data)), charCountBits)
+
+ // Append data.
+ switch dataMode {
+ case dataModeNumeric:
+ for i := 0; i < len(data); i += 3 {
+ charsRemaining := len(data) - i
+
+ var value uint32
+ bitsUsed := 1
+
+ for j := 0; j < charsRemaining && j < 3; j++ {
+ value *= 10
+ value += uint32(data[i+j] - 0x30)
+ bitsUsed += 3
+ }
+ encoded.AppendUint32(value, bitsUsed)
+ }
+ case dataModeAlphanumeric:
+ for i := 0; i < len(data); i += 2 {
+ charsRemaining := len(data) - i
+
+ var value uint32
+ for j := 0; j < charsRemaining && j < 2; j++ {
+ value *= 45
+ value += encodeAlphanumericCharacter(data[i+j])
+ }
+
+ bitsUsed := 6
+ if charsRemaining > 1 {
+ bitsUsed = 11
+ }
+
+ encoded.AppendUint32(value, bitsUsed)
+ }
+ case dataModeByte:
+ for _, b := range data {
+ encoded.AppendByte(b, 8)
+ }
+ }
+}
+
+// modeIndicator returns the segment header bits for a segment of type dataMode.
+func (d *dataEncoder) modeIndicator(dataMode dataMode) *bitset.Bitset {
+ switch dataMode {
+ case dataModeNumeric:
+ return d.numericModeIndicator
+ case dataModeAlphanumeric:
+ return d.alphanumericModeIndicator
+ case dataModeByte:
+ return d.byteModeIndicator
+ default:
+ log.Panic("Unknown data mode")
+ }
+
+ return nil
+}
+
+// charCountBits returns the number of bits used to encode the length of a data
+// segment of type dataMode.
+func (d *dataEncoder) charCountBits(dataMode dataMode) int {
+ switch dataMode {
+ case dataModeNumeric:
+ return d.numNumericCharCountBits
+ case dataModeAlphanumeric:
+ return d.numAlphanumericCharCountBits
+ case dataModeByte:
+ return d.numByteCharCountBits
+ default:
+ log.Panic("Unknown data mode")
+ }
+
+ return 0
+}
+
+// encodedLength returns the number of bits required to encode n symbols in
+// dataMode.
+//
+// The number of bits required is affected by:
+// - QR code type - Mode Indicator length.
+// - Data mode - number of bits used to represent data length.
+// - Data mode - how the data is encoded.
+// - Number of symbols encoded.
+//
+// An error is returned if the mode is not supported, or the length requested is
+// too long to be represented.
+func (d *dataEncoder) encodedLength(dataMode dataMode, n int) (int, error) {
+ modeIndicator := d.modeIndicator(dataMode)
+ charCountBits := d.charCountBits(dataMode)
+
+ if modeIndicator == nil {
+ return 0, errors.New("mode not supported")
+ }
+
+ maxLength := (1 << uint8(charCountBits)) - 1
+
+ if n > maxLength {
+ return 0, errors.New("length too long to be represented")
+ }
+
+ length := modeIndicator.Len() + charCountBits
+
+ switch dataMode {
+ case dataModeNumeric:
+ length += 10 * (n / 3)
+
+ if n%3 != 0 {
+ length += 1 + 3*(n%3)
+ }
+ case dataModeAlphanumeric:
+ length += 11 * (n / 2)
+ length += 6 * (n % 2)
+ case dataModeByte:
+ length += 8 * n
+ }
+
+ return length, nil
+}
+
+// encodeAlphanumericChar returns the QR Code encoded value of v.
+//
+// v must be a QR Code defined alphanumeric character: 0-9, A-Z, SP, $%*+-./ or
+// :. The characters are mapped to values in the range 0-44 respectively.
+func encodeAlphanumericCharacter(v byte) uint32 {
+ c := uint32(v)
+
+ switch {
+ case c >= '0' && c <= '9':
+ // 0-9 encoded as 0-9.
+ return c - '0'
+ case c >= 'A' && c <= 'Z':
+ // A-Z encoded as 10-35.
+ return c - 'A' + 10
+ case c == ' ':
+ return 36
+ case c == '$':
+ return 37
+ case c == '%':
+ return 38
+ case c == '*':
+ return 39
+ case c == '+':
+ return 40
+ case c == '-':
+ return 41
+ case c == '.':
+ return 42
+ case c == '/':
+ return 43
+ case c == ':':
+ return 44
+ default:
+ log.Panicf("encodeAlphanumericCharacter() with non alphanumeric char %v.", v)
+ }
+
+ return 0
+}