/* * QR Code generator library (C++) * * Copyright (c) 2016 Project Nayuki * https://www.nayuki.io/page/qr-code-generator-library * * (MIT License) * Permission is hereby granted, free of charge, to any person obtaining a copy of * this software and associated documentation files (the "Software"), to deal in * the Software without restriction, including without limitation the rights to * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of * the Software, and to permit persons to whom the Software is furnished to do so, * subject to the following conditions: * - The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * - The Software is provided "as is", without warranty of any kind, express or * implied, including but not limited to the warranties of merchantability, * fitness for a particular purpose and noninfringement. In no event shall the * authors or copyright holders be liable for any claim, damages or other * liability, whether in an action of contract, tort or otherwise, arising from, * out of or in connection with the Software or the use or other dealings in the * Software. */ #pragma once #include #include #include #include "QrSegment.hpp" namespace qrcodegen { /* * Represents an immutable square grid of black and white cells for a QR Code symbol, and * provides static functions to create a QR Code from user-supplied textual or binary data. * This class covers the QR Code model 2 specification, supporting all versions (sizes) * from 1 to 40, all 4 error correction levels, and only 3 character encoding modes. */ class QrCode final { /*---- Public helper enumeration ----*/ public: /* * Represents the error correction level used in a QR Code symbol. */ class Ecc final { // Constants declared in ascending order of error protection. public: const static Ecc LOW, MEDIUM, QUARTILE, HIGH; // Fields. public: const int ordinal; // In the range 0 to 3 (unsigned 2-bit integer). const int formatBits; // In the range 0 to 3 (unsigned 2-bit integer). // Constructor. private: Ecc(int ord, int fb); }; /*---- Public static factory functions ----*/ public: /* * Returns a QR Code symbol representing the given Unicode text string at the given error correction level. * As a conservative upper bound, this function is guaranteed to succeed for strings that have 738 or fewer Unicode * code points (not UTF-16 code units). The smallest possible QR Code version is automatically chosen for the output. */ static QrCode encodeText(const char *text, const Ecc &ecl); /* * Returns a QR Code segment representing the given Unicode text string. */ static QrSegment encodeTextToSegment(const char *text); /* * Returns a QR Code symbol representing the given binary data string at the given error correction level. * This function always encodes using the binary segment mode, not any text mode. The maximum number of * bytes allowed is 2953. The smallest possible QR Code version is automatically chosen for the output. */ static QrCode encodeBinary(const std::vector &data, const Ecc &ecl); /* * Returns a QR Code symbol representing the given data segments at the given error * correction level. The smallest possible QR Code version is automatically chosen for the output. * This function allows the user to create a custom sequence of segments that switches * between modes (such as alphanumeric and binary) to encode text more efficiently. This * function is considered to be lower level than simply encoding text or binary data. */ static QrCode encodeSegments(const std::vector &segs, const Ecc &ecl); /*---- Instance fields ----*/ // Public immutable scalar parameters public: /* This QR Code symbol's version number, which is always between 1 and 40 (inclusive). */ const int version; /* The width and height of this QR Code symbol, measured in modules. * Always equal to version × 4 + 17, in the range 21 to 177. */ const int size; /* The error correction level used in this QR Code symbol. */ const Ecc &errorCorrectionLevel; /* The mask pattern used in this QR Code symbol, in the range 0 to 7 (i.e. unsigned 3-bit integer). * Note that even if a constructor was called with automatic masking requested * (mask = -1), the resulting object will still have a mask value between 0 and 7. */ private: int mask; // Private grids of modules/pixels (conceptually immutable) private: std::vector> modules; // The modules of this QR Code symbol (false = white, true = black) std::vector> isFunction; // Indicates function modules that are not subjected to masking /*---- Constructors ----*/ public: /* * Creates a new QR Code symbol with the given version number, error correction level, binary data string, and mask number. * This cumbersome constructor can be invoked directly by the user, but is considered * to be even lower level than encodeSegments(). */ QrCode(int ver, const Ecc &ecl, const std::vector &dataCodewords, int mask); /* * Creates a new QR Code symbol based on the given existing object, but with a potentially * different mask pattern. The version, error correction level, codewords, etc. of the newly * created object are all identical to the argument object; only the mask may differ. */ QrCode(const QrCode &qr, int mask); /*---- Public instance methods ----*/ public: int getMask() const; /* * Returns the color of the module (pixel) at the given coordinates, which is either 0 for white or 1 for black. The top * left corner has the coordinates (x=0, y=0). If the given coordinates are out of bounds, then 0 (white) is returned. */ int getModule(int x, int y) const; /* * Based on the given number of border modules to add as padding, this returns a * string whose contents represents an SVG XML file that depicts this QR Code symbol. * Note that Unix newlines (\n) are always used, regardless of the platform. */ std::string toSvgString(int border) const; /*---- Private helper methods for constructor: Drawing function modules ----*/ private: void drawFunctionPatterns(); // Draws two copies of the format bits (with its own error correction code) // based on the given mask and this object's error correction level field. void drawFormatBits(int mask); // Draws two copies of the version bits (with its own error correction code), // based on this object's version field (which only has an effect for 7 <= version <= 40). void drawVersion(); // Draws a 9*9 finder pattern including the border separator, with the center module at (x, y). void drawFinderPattern(int x, int y); // Draws a 5*5 alignment pattern, with the center module at (x, y). void drawAlignmentPattern(int x, int y); // Sets the color of a module and marks it as a function module. // Only used by the constructor. Coordinates must be in range. void setFunctionModule(int x, int y, bool isBlack); /*---- Private helper methods for constructor: Codewords and masking ----*/ private: // Returns a new byte string representing the given data with the appropriate error correction // codewords appended to it, based on this object's version and error correction level. std::vector appendErrorCorrection(const std::vector &data) const; // Draws the given sequence of 8-bit codewords (data and error correction) onto the entire // data area of this QR Code symbol. Function modules need to be marked off before this is called. void drawCodewords(const std::vector &data); // XORs the data modules in this QR Code with the given mask pattern. Due to XOR's mathematical // properties, calling applyMask(m) twice with the same value is equivalent to no change at all. // This means it is possible to apply a mask, undo it, and try another mask. Note that a final // well-formed QR Code symbol needs exactly one mask applied (not zero, not two, etc.). void applyMask(int mask); // A messy helper function for the constructors. This QR Code must be in an unmasked state when this // method is called. The given argument is the requested mask, which is -1 for auto or 0 to 7 for fixed. // This method applies and returns the actual mask chosen, from 0 to 7. int handleConstructorMasking(int mask); // Calculates and returns the penalty score based on state of this QR Code's current modules. // This is used by the automatic mask choice algorithm to find the mask pattern that yields the lowest score. int getPenaltyScore() const; /*---- Static helper functions ----*/ private: // Returns a set of positions of the alignment patterns in ascending order. These positions are // used on both the x and y axes. Each value in the resulting array is in the range [0, 177). // This stateless pure function could be implemented as table of 40 variable-length lists of unsigned bytes. static std::vector getAlignmentPatternPositions(int ver); // Returns the number of raw data modules (bits) available at the given version number. // These data modules are used for both user data codewords and error correction codewords. // This stateless pure function could be implemented as a 40-entry lookup table. static int getNumRawDataModules(int ver); // Returns the number of 8-bit data (i.e. not error correction) codewords contained in any // QR Code of the given version number and error correction level, with remainder bits discarded. // This stateless pure function could be implemented as a (40*4)-cell lookup table. static int getNumDataCodewords(int ver, const Ecc &ecl); /*---- Tables of constants ----*/ private: // For use in getPenaltyScore(), when evaluating which mask is best. static const int PENALTY_N1; static const int PENALTY_N2; static const int PENALTY_N3; static const int PENALTY_N4; static const int16_t NUM_ERROR_CORRECTION_CODEWORDS[4][41]; static const int8_t NUM_ERROR_CORRECTION_BLOCKS[4][41]; /*---- Private helper class ----*/ private: /* * Computes the Reed-Solomon error correction codewords for a sequence of data codewords * at a given degree. Objects are immutable, and the state only depends on the degree. * This class exists because the divisor polynomial does not need to be recalculated for every input. */ class ReedSolomonGenerator final { /*-- Immutable field --*/ private: // Coefficients of the divisor polynomial, stored from highest to lowest power, excluding the leading term which // is always 1. For example the polynomial x^3 + 255x^2 + 8x + 93 is stored as the uint8 array {255, 8, 93}. std::vector coefficients; /*-- Constructor --*/ public: /* * Creates a Reed-Solomon ECC generator for the given degree. This could be implemented * as a lookup table over all possible parameter values, instead of as an algorithm. */ ReedSolomonGenerator(int degree); /*-- Method --*/ public: /* * Computes and returns the Reed-Solomon error correction codewords for the given sequence of data codewords. * The returned object is always a new byte array. This method does not alter this object's state (because it is immutable). */ std::vector getRemainder(const std::vector &data) const; /*-- Static function --*/ private: // Returns the product of the two given field elements modulo GF(2^8/0x11D). The arguments and result // are unsigned 8-bit integers. This could be implemented as a lookup table of 256*256 entries of uint8. static uint8_t multiply(uint8_t x, uint8_t y); }; }; }