/* * QR Code generator library (C++) * * Copyright (c) Project Nayuki. (MIT License) * https://www.nayuki.io/page/qr-code-generator-library * * 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 #include "QrSegment.hpp" namespace qrcodegen { /* * A QR Code symbol, which is a type of two-dimension barcode. * Invented by Denso Wave and described in the ISO/IEC 18004 standard. * Instances of this class represent an immutable square grid of black and white cells. * The class provides static factory functions to create a QR Code from text or binary data. * The class covers the QR Code Model 2 specification, supporting all versions (sizes) * from 1 to 40, all 4 error correction levels, and 4 character encoding modes. * * Ways to create a QR Code object: * - High level: Take the payload data and call QrCode::encodeText() or QrCode::encodeBinary(). * - Mid level: Custom-make the list of segments and call QrCode::encodeSegments(). * - Low level: Custom-make the array of data codeword bytes (including * segment headers and final padding, excluding error correction codewords), * supply the appropriate version number, and call the QrCode() constructor. * (Note that all ways require supplying the desired error correction level.) */ class QrCode final { /*---- Public helper enumeration ----*/ /* * The error correction level in a QR Code symbol. */ public: enum class Ecc { LOW = 0 , // The QR Code can tolerate about 7% erroneous codewords MEDIUM , // The QR Code can tolerate about 15% erroneous codewords QUARTILE, // The QR Code can tolerate about 25% erroneous codewords HIGH , // The QR Code can tolerate about 30% erroneous codewords }; // Returns a value in the range 0 to 3 (unsigned 2-bit integer). private: static int getFormatBits(Ecc ecl); /*---- Static factory functions (high level) ----*/ /* * Returns a QR Code 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 2953 or fewer * UTF-8 code units (not Unicode code points) if the low error correction level is used. The smallest possible * QR Code version is automatically chosen for the output. The ECC level of the result may be higher than * the ecl argument if it can be done without increasing the version. */ public: static QrCode encodeText(const char *text, Ecc ecl); /* * Returns a QR Code representing the given binary data 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. * The ECC level of the result may be higher than the ecl argument if it can be done without increasing the version. */ public: static QrCode encodeBinary(const std::vector &data, Ecc ecl); /*---- Static factory functions (mid level) ----*/ /* * Returns a QR Code representing the given segments with the given encoding parameters. * The smallest possible QR Code version within the given range is automatically * chosen for the output. Iff boostEcl is true, then the ECC level of the result * may be higher than the ecl argument if it can be done without increasing the * version. The mask number is either between 0 to 7 (inclusive) to force that * mask, or -1 to automatically choose an appropriate mask (which may be slow). * This function allows the user to create a custom sequence of segments that switches * between modes (such as alphanumeric and byte) to encode text in less space. * This is a mid-level API; the high-level API is encodeText() and encodeBinary(). */ public: static QrCode encodeSegments(const std::vector &segs, Ecc ecl, int minVersion=1, int maxVersion=40, int mask=-1, bool boostEcl=true); // All optional parameters /*---- Instance fields ----*/ // Immutable scalar parameters: /* The version number of this QR Code, which is between 1 and 40 (inclusive). * This determines the size of this barcode. */ private: int version; /* The width and height of this QR Code, measured in modules, between * 21 and 177 (inclusive). This is equal to version * 4 + 17. */ private: int size; /* The error correction level used in this QR Code. */ private: Ecc errorCorrectionLevel; /* The index of the mask pattern used in this QR Code, which is between 0 and 7 (inclusive). * Even if a QR Code is created with automatic masking requested (mask = -1), * the resulting object still has a mask value between 0 and 7. */ private: int mask; // Private grids of modules/pixels, with dimensions of size*size: // The modules of this QR Code (false = white, true = black). // Immutable after constructor finishes. Accessed through getModule(). private: std::vector > modules; // Indicates function modules that are not subjected to masking. Discarded when constructor finishes. private: std::vector > isFunction; /*---- Constructor (low level) ----*/ /* * Creates a new QR Code with the given version number, * error correction level, data codeword bytes, and mask number. * This is a low-level API that most users should not use directly. * A mid-level API is the encodeSegments() function. */ public: QrCode(int ver, Ecc ecl, const std::vector &dataCodewords, int mask); /*---- Public instance methods ----*/ /* * Returns this QR Code's version, in the range [1, 40]. */ public: int getVersion() const; /* * Returns this QR Code's size, in the range [21, 177]. */ public: int getSize() const; /* * Returns this QR Code's error correction level. */ public: Ecc getErrorCorrectionLevel() const; /* * Returns this QR Code's mask, in the range [0, 7]. */ public: int getMask() const; /* * Returns the color of the module (pixel) at the given coordinates, which is false * for white or true for black. The top left corner has the coordinates (x=0, y=0). * If the given coordinates are out of bounds, then false (white) is returned. */ public: bool getModule(int x, int y) const; /* * Returns a string of SVG code for an image depicting this QR Code, with the given number * of border modules. The string always uses Unix newlines (\n), regardless of the platform. */ public: std::string toSvgString(int border) const; /*---- Private helper methods for constructor: Drawing function modules ----*/ // Reads this object's version field, and draws and marks all 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. private: void drawFormatBits(int mask); // Draws two copies of the version bits (with its own error correction code), // based on this object's version field, iff 7 <= version <= 40. private: void drawVersion(); // Draws a 9*9 finder pattern including the border separator, // with the center module at (x, y). Modules can be out of bounds. private: void drawFinderPattern(int x, int y); // Draws a 5*5 alignment pattern, with the center module // at (x, y). All modules must be in bounds. private: 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 bounds. private: void setFunctionModule(int x, int y, bool isBlack); // Returns the color of the module at the given coordinates, which must be in range. private: bool module(int x, int y) const; /*---- Private helper methods for constructor: Codewords and masking ----*/ // 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. private: std::vector addEccAndInterleave(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. Function modules need to be marked off before this is called. private: void drawCodewords(const std::vector &data); // XORs the codeword modules in this QR Code with the given mask pattern. // The function modules must be marked and the codeword bits must be drawn // before masking. Due to the arithmetic of XOR, calling applyMask() with // the same mask value a second time will undo the mask. A final well-formed // QR Code needs exactly one (not zero, two, etc.) mask applied. private: 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. private: 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. private: long getPenaltyScore() const; /*---- Private helper functions ----*/ // Returns an ascending list of positions of alignment patterns for this version number. // Each position is in the range [0,177), and are used on both the x and y axes. // This could be implemented as lookup table of 40 variable-length lists of unsigned bytes. private: std::vector getAlignmentPatternPositions() const; // Returns the number of data bits that can be stored in a QR Code of the given version number, after // all function modules are excluded. This includes remainder bits, so it might not be a multiple of 8. // The result is in the range [208, 29648]. This could be implemented as a 40-entry lookup table. private: 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. private: static int getNumDataCodewords(int ver, Ecc ecl); // Inserts the given value to the front of the given array, which shifts over the // existing values and deletes the last value. A helper function for getPenaltyScore(). private: static void addRunToHistory(int run, std::deque &history); // Tests whether the given run history has the pattern of ratio 1:1:3:1:1 in the middle, and // surrounded by at least 4 on either or both ends. A helper function for getPenaltyScore(). // Must only be called immediately after a run of white modules has ended. private: static bool hasFinderLikePattern(const std::deque &runHistory); // Returns true iff the i'th bit of x is set to 1. private: static bool getBit(long x, int i); /*---- Constants and tables ----*/ // The minimum version number supported in the QR Code Model 2 standard. public: static constexpr int MIN_VERSION = 1; // The maximum version number supported in the QR Code Model 2 standard. public: static constexpr int MAX_VERSION = 40; // For use in getPenaltyScore(), when evaluating which mask is best. private: static const int PENALTY_N1; private: static const int PENALTY_N2; private: static const int PENALTY_N3; private: static const int PENALTY_N4; private: static const std::int8_t ECC_CODEWORDS_PER_BLOCK[4][41]; private: static const std::int8_t NUM_ERROR_CORRECTION_BLOCKS[4][41]; /*---- Private helper class ----*/ /* * 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 each data block in a QR Code shares the same the divisor polynomial. */ private: class ReedSolomonGenerator final { /*-- Immutable field --*/ // 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}. private: std::vector coefficients; /*-- Constructor --*/ /* * 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. */ public: explicit ReedSolomonGenerator(int degree); /*-- Method --*/ /* * 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). */ public: std::vector getRemainder(const std::vector &data) const; /*-- Static function --*/ // Returns the product of the two given field elements modulo GF(2^8/0x11D). // All inputs are valid. This could be implemented as a 256*256 lookup table. private: static std::uint8_t multiply(std::uint8_t x, std::uint8_t y); }; }; /*---- Public exception class ----*/ /* * Thrown when the supplied data does not fit any QR Code version. Ways to handle this exception include: * - Decrease the error correction level if it was greater than Ecc::LOW. * - If the encodeSegments() function was called with a maxVersion argument, then increase * it if it was less than QrCode::MAX_VERSION. (This advice does not apply to the other * factory functions because they search all versions up to QrCode::MAX_VERSION.) * - Split the text data into better or optimal segments in order to reduce the number of bits required. * - Change the text or binary data to be shorter. * - Change the text to fit the character set of a particular segment mode (e.g. alphanumeric). * - Propagate the error upward to the caller/user. */ class data_too_long : public std::length_error { public: explicit data_too_long(const std::string &msg); }; }