1/* 2 * QR Code generator library (C++) 3 * 4 * Copyright (c) Project Nayuki. (MIT License) 5 * https://www.nayuki.io/page/qr-code-generator-library 6 * 7 * Permission is hereby granted, free of charge, to any person obtaining a copy of 8 * this software and associated documentation files (the "Software"), to deal in 9 * the Software without restriction, including without limitation the rights to 10 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of 11 * the Software, and to permit persons to whom the Software is furnished to do so, 12 * subject to the following conditions: 13 * - The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * - The Software is provided "as is", without warranty of any kind, express or 16 * implied, including but not limited to the warranties of merchantability, 17 * fitness for a particular purpose and noninfringement. In no event shall the 18 * authors or copyright holders be liable for any claim, damages or other 19 * liability, whether in an action of contract, tort or otherwise, arising from, 20 * out of or in connection with the Software or the use or other dealings in the 21 * Software. 22 */ 23 24#pragma once 25 26#include <array> 27#include <cstdint> 28#include <stdexcept> 29#include <string> 30#include <vector> 31 32 33namespace qrcodegen { 34 35/* 36 * A segment of character/binary/control data in a QR Code symbol. 37 * Instances of this class are immutable. 38 * The mid-level way to create a segment is to take the payload data 39 * and call a static factory function such as QrSegment::makeNumeric(). 40 * The low-level way to create a segment is to custom-make the bit buffer 41 * and call the QrSegment() constructor with appropriate values. 42 * This segment class imposes no length restrictions, but QR Codes have restrictions. 43 * Even in the most favorable conditions, a QR Code can only hold 7089 characters of data. 44 * Any segment longer than this is meaningless for the purpose of generating QR Codes. 45 */ 46class QrSegment final { 47 48 /*---- Public helper enumeration ----*/ 49 50 /* 51 * Describes how a segment's data bits are interpreted. Immutable. 52 */ 53 public: class Mode final { 54 55 /*-- Constants --*/ 56 57 public: static const Mode NUMERIC; 58 public: static const Mode ALPHANUMERIC; 59 public: static const Mode BYTE; 60 public: static const Mode KANJI; 61 public: static const Mode ECI; 62 63 64 /*-- Fields --*/ 65 66 // The mode indicator bits, which is a uint4 value (range 0 to 15). 67 private: int modeBits; 68 69 // Number of character count bits for three different version ranges. 70 private: int numBitsCharCount[3]; 71 72 73 /*-- Constructor --*/ 74 75 private: Mode(int mode, int cc0, int cc1, int cc2); 76 77 78 /*-- Methods --*/ 79 80 /* 81 * (Package-private) Returns the mode indicator bits, which is an unsigned 4-bit value (range 0 to 15). 82 */ 83 public: int getModeBits() const; 84 85 /* 86 * (Package-private) Returns the bit width of the character count field for a segment in 87 * this mode in a QR Code at the given version number. The result is in the range [0, 16]. 88 */ 89 public: int numCharCountBits(int ver) const; 90 91 }; 92 93 94 95 /*---- Static factory functions (mid level) ----*/ 96 97 /* 98 * Returns a segment representing the given binary data encoded in 99 * byte mode. All input byte vectors are acceptable. Any text string 100 * can be converted to UTF-8 bytes and encoded as a byte mode segment. 101 */ 102 public: static QrSegment makeBytes(const std::vector<std::uint8_t> &data); 103 104 105 /* 106 * Returns a segment representing the given string of decimal digits encoded in numeric mode. 107 */ 108 public: static QrSegment makeNumeric(const char *digits); 109 110 111 /* 112 * Returns a segment representing the given text string encoded in alphanumeric mode. 113 * The characters allowed are: 0 to 9, A to Z (uppercase only), space, 114 * dollar, percent, asterisk, plus, hyphen, period, slash, colon. 115 */ 116 public: static QrSegment makeAlphanumeric(const char *text); 117 118 119 /* 120 * Returns a list of zero or more segments to represent the given text string. The result 121 * may use various segment modes and switch modes to optimize the length of the bit stream. 122 */ 123 public: static std::vector<QrSegment> makeSegments(const char *text); 124 125 126 /* 127 * Returns a segment representing an Extended Channel Interpretation 128 * (ECI) designator with the given assignment value. 129 */ 130 public: static QrSegment makeEci(long assignVal); 131 132 133 /*---- Public static helper functions ----*/ 134 135 /* 136 * Tests whether the given string can be encoded as a segment in numeric mode. 137 * A string is encodable iff each character is in the range 0 to 9. 138 */ 139 public: static bool isNumeric(const char *text); 140 141 142 /* 143 * Tests whether the given string can be encoded as a segment in alphanumeric mode. 144 * A string is encodable iff each character is in the following set: 0 to 9, A to Z 145 * (uppercase only), space, dollar, percent, asterisk, plus, hyphen, period, slash, colon. 146 */ 147 public: static bool isAlphanumeric(const char *text); 148 149 150 151 /*---- Instance fields ----*/ 152 153 /* The mode indicator of this segment. Accessed through getMode(). */ 154 private: const Mode *mode; 155 156 /* The length of this segment's unencoded data. Measured in characters for 157 * numeric/alphanumeric/kanji mode, bytes for byte mode, and 0 for ECI mode. 158 * Always zero or positive. Not the same as the data's bit length. 159 * Accessed through getNumChars(). */ 160 private: int numChars; 161 162 /* The data bits of this segment. Accessed through getData(). */ 163 private: std::vector<bool> data; 164 165 166 /*---- Constructors (low level) ----*/ 167 168 /* 169 * Creates a new QR Code segment with the given attributes and data. 170 * The character count (numCh) must agree with the mode and the bit buffer length, 171 * but the constraint isn't checked. The given bit buffer is copied and stored. 172 */ 173 public: QrSegment(const Mode &md, int numCh, const std::vector<bool> &dt); 174 175 176 /* 177 * Creates a new QR Code segment with the given parameters and data. 178 * The character count (numCh) must agree with the mode and the bit buffer length, 179 * but the constraint isn't checked. The given bit buffer is moved and stored. 180 */ 181 public: QrSegment(const Mode &md, int numCh, std::vector<bool> &&dt); 182 183 184 /*---- Methods ----*/ 185 186 /* 187 * Returns the mode field of this segment. 188 */ 189 public: const Mode &getMode() const; 190 191 192 /* 193 * Returns the character count field of this segment. 194 */ 195 public: int getNumChars() const; 196 197 198 /* 199 * Returns the data bits of this segment. 200 */ 201 public: const std::vector<bool> &getData() const; 202 203 204 // (Package-private) Calculates the number of bits needed to encode the given segments at 205 // the given version. Returns a non-negative number if successful. Otherwise returns -1 if a 206 // segment has too many characters to fit its length field, or the total bits exceeds INT_MAX. 207 public: static int getTotalBits(const std::vector<QrSegment> &segs, int version); 208 209 210 /*---- Private constant ----*/ 211 212 /* The set of all legal characters in alphanumeric mode, where 213 * each character value maps to the index in the string. */ 214 private: static const char *ALPHANUMERIC_CHARSET; 215 216}; 217 218 219 220/* 221 * A QR Code symbol, which is a type of two-dimension barcode. 222 * Invented by Denso Wave and described in the ISO/IEC 18004 standard. 223 * Instances of this class represent an immutable square grid of dark and light cells. 224 * The class provides static factory functions to create a QR Code from text or binary data. 225 * The class covers the QR Code Model 2 specification, supporting all versions (sizes) 226 * from 1 to 40, all 4 error correction levels, and 4 character encoding modes. 227 * 228 * Ways to create a QR Code object: 229 * - High level: Take the payload data and call QrCode::encodeText() or QrCode::encodeBinary(). 230 * - Mid level: Custom-make the list of segments and call QrCode::encodeSegments(). 231 * - Low level: Custom-make the array of data codeword bytes (including 232 * segment headers and final padding, excluding error correction codewords), 233 * supply the appropriate version number, and call the QrCode() constructor. 234 * (Note that all ways require supplying the desired error correction level.) 235 */ 236class QrCode final { 237 238 /*---- Public helper enumeration ----*/ 239 240 /* 241 * The error correction level in a QR Code symbol. 242 */ 243 public: enum class Ecc { 244 LOW = 0 , // The QR Code can tolerate about 7% erroneous codewords 245 MEDIUM , // The QR Code can tolerate about 15% erroneous codewords 246 QUARTILE, // The QR Code can tolerate about 25% erroneous codewords 247 HIGH , // The QR Code can tolerate about 30% erroneous codewords 248 }; 249 250 251 // Returns a value in the range 0 to 3 (unsigned 2-bit integer). 252 private: static int getFormatBits(Ecc ecl); 253 254 255 256 /*---- Static factory functions (high level) ----*/ 257 258 /* 259 * Returns a QR Code representing the given Unicode text string at the given error correction level. 260 * As a conservative upper bound, this function is guaranteed to succeed for strings that have 2953 or fewer 261 * UTF-8 code units (not Unicode code points) if the low error correction level is used. The smallest possible 262 * QR Code version is automatically chosen for the output. The ECC level of the result may be higher than 263 * the ecl argument if it can be done without increasing the version. 264 */ 265 public: static QrCode encodeText(const char *text, Ecc ecl); 266 267 268 /* 269 * Returns a QR Code representing the given binary data at the given error correction level. 270 * This function always encodes using the binary segment mode, not any text mode. The maximum number of 271 * bytes allowed is 2953. The smallest possible QR Code version is automatically chosen for the output. 272 * The ECC level of the result may be higher than the ecl argument if it can be done without increasing the version. 273 */ 274 public: static QrCode encodeBinary(const std::vector<std::uint8_t> &data, Ecc ecl); 275 276 277 /*---- Static factory functions (mid level) ----*/ 278 279 /* 280 * Returns a QR Code representing the given segments with the given encoding parameters. 281 * The smallest possible QR Code version within the given range is automatically 282 * chosen for the output. Iff boostEcl is true, then the ECC level of the result 283 * may be higher than the ecl argument if it can be done without increasing the 284 * version. The mask number is either between 0 to 7 (inclusive) to force that 285 * mask, or -1 to automatically choose an appropriate mask (which may be slow). 286 * This function allows the user to create a custom sequence of segments that switches 287 * between modes (such as alphanumeric and byte) to encode text in less space. 288 * This is a mid-level API; the high-level API is encodeText() and encodeBinary(). 289 */ 290 public: static QrCode encodeSegments(const std::vector<QrSegment> &segs, Ecc ecl, 291 int minVersion=1, int maxVersion=40, int mask=-1, bool boostEcl=true); // All optional parameters 292 293 294 295 /*---- Instance fields ----*/ 296 297 // Immutable scalar parameters: 298 299 /* The version number of this QR Code, which is between 1 and 40 (inclusive). 300 * This determines the size of this barcode. */ 301 private: int version; 302 303 /* The width and height of this QR Code, measured in modules, between 304 * 21 and 177 (inclusive). This is equal to version * 4 + 17. */ 305 private: int size; 306 307 /* The error correction level used in this QR Code. */ 308 private: Ecc errorCorrectionLevel; 309 310 /* The index of the mask pattern used in this QR Code, which is between 0 and 7 (inclusive). 311 * Even if a QR Code is created with automatic masking requested (mask = -1), 312 * the resulting object still has a mask value between 0 and 7. */ 313 private: int mask; 314 315 // Private grids of modules/pixels, with dimensions of size*size: 316 317 // The modules of this QR Code (false = light, true = dark). 318 // Immutable after constructor finishes. Accessed through getModule(). 319 private: std::vector<std::vector<bool> > modules; 320 321 // Indicates function modules that are not subjected to masking. Discarded when constructor finishes. 322 private: std::vector<std::vector<bool> > isFunction; 323 324 325 326 /*---- Constructor (low level) ----*/ 327 328 /* 329 * Creates a new QR Code with the given version number, 330 * error correction level, data codeword bytes, and mask number. 331 * This is a low-level API that most users should not use directly. 332 * A mid-level API is the encodeSegments() function. 333 */ 334 public: QrCode(int ver, Ecc ecl, const std::vector<std::uint8_t> &dataCodewords, int msk); 335 336 337 338 /*---- Public instance methods ----*/ 339 340 /* 341 * Returns this QR Code's version, in the range [1, 40]. 342 */ 343 public: int getVersion() const; 344 345 346 /* 347 * Returns this QR Code's size, in the range [21, 177]. 348 */ 349 public: int getSize() const; 350 351 352 /* 353 * Returns this QR Code's error correction level. 354 */ 355 public: Ecc getErrorCorrectionLevel() const; 356 357 358 /* 359 * Returns this QR Code's mask, in the range [0, 7]. 360 */ 361 public: int getMask() const; 362 363 364 /* 365 * Returns the color of the module (pixel) at the given coordinates, which is false 366 * for light or true for dark. The top left corner has the coordinates (x=0, y=0). 367 * If the given coordinates are out of bounds, then false (light) is returned. 368 */ 369 public: bool getModule(int x, int y) const; 370 371 372 373 /*---- Private helper methods for constructor: Drawing function modules ----*/ 374 375 // Reads this object's version field, and draws and marks all function modules. 376 private: void drawFunctionPatterns(); 377 378 379 // Draws two copies of the format bits (with its own error correction code) 380 // based on the given mask and this object's error correction level field. 381 private: void drawFormatBits(int msk); 382 383 384 // Draws two copies of the version bits (with its own error correction code), 385 // based on this object's version field, iff 7 <= version <= 40. 386 private: void drawVersion(); 387 388 389 // Draws a 9*9 finder pattern including the border separator, 390 // with the center module at (x, y). Modules can be out of bounds. 391 private: void drawFinderPattern(int x, int y); 392 393 394 // Draws a 5*5 alignment pattern, with the center module 395 // at (x, y). All modules must be in bounds. 396 private: void drawAlignmentPattern(int x, int y); 397 398 399 // Sets the color of a module and marks it as a function module. 400 // Only used by the constructor. Coordinates must be in bounds. 401 private: void setFunctionModule(int x, int y, bool isDark); 402 403 404 // Returns the color of the module at the given coordinates, which must be in range. 405 private: bool module(int x, int y) const; 406 407 408 /*---- Private helper methods for constructor: Codewords and masking ----*/ 409 410 // Returns a new byte string representing the given data with the appropriate error correction 411 // codewords appended to it, based on this object's version and error correction level. 412 private: std::vector<std::uint8_t> addEccAndInterleave(const std::vector<std::uint8_t> &data) const; 413 414 415 // Draws the given sequence of 8-bit codewords (data and error correction) onto the entire 416 // data area of this QR Code. Function modules need to be marked off before this is called. 417 private: void drawCodewords(const std::vector<std::uint8_t> &data); 418 419 420 // XORs the codeword modules in this QR Code with the given mask pattern. 421 // The function modules must be marked and the codeword bits must be drawn 422 // before masking. Due to the arithmetic of XOR, calling applyMask() with 423 // the same mask value a second time will undo the mask. A final well-formed 424 // QR Code needs exactly one (not zero, two, etc.) mask applied. 425 private: void applyMask(int msk); 426 427 428 // Calculates and returns the penalty score based on state of this QR Code's current modules. 429 // This is used by the automatic mask choice algorithm to find the mask pattern that yields the lowest score. 430 private: long getPenaltyScore() const; 431 432 433 434 /*---- Private helper functions ----*/ 435 436 // Returns an ascending list of positions of alignment patterns for this version number. 437 // Each position is in the range [0,177), and are used on both the x and y axes. 438 // This could be implemented as lookup table of 40 variable-length lists of unsigned bytes. 439 private: std::vector<int> getAlignmentPatternPositions() const; 440 441 442 // Returns the number of data bits that can be stored in a QR Code of the given version number, after 443 // all function modules are excluded. This includes remainder bits, so it might not be a multiple of 8. 444 // The result is in the range [208, 29648]. This could be implemented as a 40-entry lookup table. 445 private: static int getNumRawDataModules(int ver); 446 447 448 // Returns the number of 8-bit data (i.e. not error correction) codewords contained in any 449 // QR Code of the given version number and error correction level, with remainder bits discarded. 450 // This stateless pure function could be implemented as a (40*4)-cell lookup table. 451 private: static int getNumDataCodewords(int ver, Ecc ecl); 452 453 454 // Returns a Reed-Solomon ECC generator polynomial for the given degree. This could be 455 // implemented as a lookup table over all possible parameter values, instead of as an algorithm. 456 private: static std::vector<std::uint8_t> reedSolomonComputeDivisor(int degree); 457 458 459 // Returns the Reed-Solomon error correction codeword for the given data and divisor polynomials. 460 private: static std::vector<std::uint8_t> reedSolomonComputeRemainder(const std::vector<std::uint8_t> &data, const std::vector<std::uint8_t> &divisor); 461 462 463 // Returns the product of the two given field elements modulo GF(2^8/0x11D). 464 // All inputs are valid. This could be implemented as a 256*256 lookup table. 465 private: static std::uint8_t reedSolomonMultiply(std::uint8_t x, std::uint8_t y); 466 467 468 // Can only be called immediately after a light run is added, and 469 // returns either 0, 1, or 2. A helper function for getPenaltyScore(). 470 private: int finderPenaltyCountPatterns(const std::array<int,7> &runHistory) const; 471 472 473 // Must be called at the end of a line (row or column) of modules. A helper function for getPenaltyScore(). 474 private: int finderPenaltyTerminateAndCount(bool currentRunColor, int currentRunLength, std::array<int,7> &runHistory) const; 475 476 477 // Pushes the given value to the front and drops the last value. A helper function for getPenaltyScore(). 478 private: void finderPenaltyAddHistory(int currentRunLength, std::array<int,7> &runHistory) const; 479 480 481 // Returns true iff the i'th bit of x is set to 1. 482 private: static bool getBit(long x, int i); 483 484 485 /*---- Constants and tables ----*/ 486 487 // The minimum version number supported in the QR Code Model 2 standard. 488 public: static constexpr int MIN_VERSION = 1; 489 490 // The maximum version number supported in the QR Code Model 2 standard. 491 public: static constexpr int MAX_VERSION = 40; 492 493 494 // For use in getPenaltyScore(), when evaluating which mask is best. 495 private: static const int PENALTY_N1; 496 private: static const int PENALTY_N2; 497 private: static const int PENALTY_N3; 498 private: static const int PENALTY_N4; 499 500 501 private: static const std::int8_t ECC_CODEWORDS_PER_BLOCK[4][41]; 502 private: static const std::int8_t NUM_ERROR_CORRECTION_BLOCKS[4][41]; 503 504}; 505 506 507 508/*---- Public exception class ----*/ 509 510/* 511 * Thrown when the supplied data does not fit any QR Code version. Ways to handle this exception include: 512 * - Decrease the error correction level if it was greater than Ecc::LOW. 513 * - If the encodeSegments() function was called with a maxVersion argument, then increase 514 * it if it was less than QrCode::MAX_VERSION. (This advice does not apply to the other 515 * factory functions because they search all versions up to QrCode::MAX_VERSION.) 516 * - Split the text data into better or optimal segments in order to reduce the number of bits required. 517 * - Change the text or binary data to be shorter. 518 * - Change the text to fit the character set of a particular segment mode (e.g. alphanumeric). 519 * - Propagate the error upward to the caller/user. 520 */ 521class data_too_long : public std::length_error { 522 523 public: explicit data_too_long(const std::string &msg); 524 525}; 526 527 528 529/* 530 * An appendable sequence of bits (0s and 1s). Mainly used by QrSegment. 531 */ 532class BitBuffer final : public std::vector<bool> { 533 534 /*---- Constructor ----*/ 535 536 // Creates an empty bit buffer (length 0). 537 public: BitBuffer(); 538 539 540 541 /*---- Method ----*/ 542 543 // Appends the given number of low-order bits of the given value 544 // to this buffer. Requires 0 <= len <= 31 and val < 2^len. 545 public: void appendBits(std::uint32_t val, int len); 546 547}; 548 549} 550