/* * 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 <array> #include <cstdint> #include <stdexcept> #include <string> #include <vector> namespace qrcodegen { /* * A segment of character/binary/control data in a QR Code symbol. * Instances of this class are immutable. * The mid-level way to create a segment is to take the payload data * and call a static factory function such as QrSegment::makeNumeric(). * The low-level way to create a segment is to custom-make the bit buffer * and call the QrSegment() constructor with appropriate values. * This segment class imposes no length restrictions, but QR Codes have restrictions. * Even in the most favorable conditions, a QR Code can only hold 7089 characters of data. * Any segment longer than this is meaningless for the purpose of generating QR Codes. */ class QrSegment final { /*---- Public helper enumeration ----*/ /* * Describes how a segment's data bits are interpreted. Immutable. */ public: class Mode final { /*-- Constants --*/ public: static const Mode NUMERIC; public: static const Mode ALPHANUMERIC; public: static const Mode BYTE; public: static const Mode KANJI; public: static const Mode ECI; /*-- Fields --*/ // The mode indicator bits, which is a uint4 value (range 0 to 15). private: int modeBits; // Number of character count bits for three different version ranges. private: int numBitsCharCount[3]; /*-- Constructor --*/ private: Mode(int mode, int cc0, int cc1, int cc2); /*-- Methods --*/ /* * (Package-private) Returns the mode indicator bits, which is an unsigned 4-bit value (range 0 to 15). */ public: int getModeBits() const; /* * (Package-private) Returns the bit width of the character count field for a segment in * this mode in a QR Code at the given version number. The result is in the range [0, 16]. */ public: int numCharCountBits(int ver) const; }; /*---- Static factory functions (mid level) ----*/ /* * Returns a segment representing the given binary data encoded in * byte mode. All input byte vectors are acceptable. Any text string * can be converted to UTF-8 bytes and encoded as a byte mode segment. */ public: static QrSegment makeBytes(const std::vector<std::uint8_t> &data); /* * Returns a segment representing the given string of decimal digits encoded in numeric mode. */ public: static QrSegment makeNumeric(const char *digits); /* * Returns a segment representing the given text string encoded in alphanumeric mode. * The characters allowed are: 0 to 9, A to Z (uppercase only), space, * dollar, percent, asterisk, plus, hyphen, period, slash, colon. */ public: static QrSegment makeAlphanumeric(const char *text); /* * Returns a list of zero or more segments to represent the given text string. The result * may use various segment modes and switch modes to optimize the length of the bit stream. */ public: static std::vector<QrSegment> makeSegments(const char *text); /* * Returns a segment representing an Extended Channel Interpretation * (ECI) designator with the given assignment value. */ public: static QrSegment makeEci(long assignVal); /*---- Public static helper functions ----*/ /* * Tests whether the given string can be encoded as a segment in alphanumeric mode. * A string is encodable iff each character is in the following set: 0 to 9, A to Z * (uppercase only), space, dollar, percent, asterisk, plus, hyphen, period, slash, colon. */ public: static bool isAlphanumeric(const char *text); /* * Tests whether the given string can be encoded as a segment in numeric mode. * A string is encodable iff each character is in the range 0 to 9. */ public: static bool isNumeric(const char *text); /*---- Instance fields ----*/ /* The mode indicator of this segment. Accessed through getMode(). */ private: Mode mode; /* The length of this segment's unencoded data. Measured in characters for * numeric/alphanumeric/kanji mode, bytes for byte mode, and 0 for ECI mode. * Always zero or positive. Not the same as the data's bit length. * Accessed through getNumChars(). */ private: int numChars; /* The data bits of this segment. Accessed through getData(). */ private: std::vector<bool> data; /*---- Constructors (low level) ----*/ /* * Creates a new QR Code segment with the given attributes and data. * The character count (numCh) must agree with the mode and the bit buffer length, * but the constraint isn't checked. The given bit buffer is copied and stored. */ public: QrSegment(Mode md, int numCh, const std::vector<bool> &dt); /* * Creates a new QR Code segment with the given parameters and data. * The character count (numCh) must agree with the mode and the bit buffer length, * but the constraint isn't checked. The given bit buffer is moved and stored. */ public: QrSegment(Mode md, int numCh, std::vector<bool> &&dt); /*---- Methods ----*/ /* * Returns the mode field of this segment. */ public: Mode getMode() const; /* * Returns the character count field of this segment. */ public: int getNumChars() const; /* * Returns the data bits of this segment. */ public: const std::vector<bool> &getData() const; // (Package-private) Calculates the number of bits needed to encode the given segments at // the given version. Returns a non-negative number if successful. Otherwise returns -1 if a // segment has too many characters to fit its length field, or the total bits exceeds INT_MAX. public: static int getTotalBits(const std::vector<QrSegment> &segs, int version); /*---- Private constant ----*/ /* The set of all legal characters in alphanumeric mode, where * each character value maps to the index in the string. */ private: static const char *ALPHANUMERIC_CHARSET; }; /* * 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<std::uint8_t> &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<QrSegment> &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<std::vector<bool> > modules; // Indicates function modules that are not subjected to masking. Discarded when constructor finishes. private: std::vector<std::vector<bool> > 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<std::uint8_t> &dataCodewords, int msk); /*---- 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 msk); // 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<std::uint8_t> addEccAndInterleave(const std::vector<std::uint8_t> &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<std::uint8_t> &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 msk); // 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<int> 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); // Returns a Reed-Solomon ECC generator polynomial for the given degree. This could be // implemented as a lookup table over all possible parameter values, instead of as an algorithm. private: static std::vector<std::uint8_t> reedSolomonComputeDivisor(int degree); // Returns the Reed-Solomon error correction codeword for the given data and divisor polynomials. private: static std::vector<std::uint8_t> reedSolomonComputeRemainder(const std::vector<std::uint8_t> &data, const std::vector<std::uint8_t> &divisor); // 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 reedSolomonMultiply(std::uint8_t x, std::uint8_t y); // Can only be called immediately after a white run is added, and // returns either 0, 1, or 2. A helper function for getPenaltyScore(). private: int finderPenaltyCountPatterns(const std::array<int,7> &runHistory) const; // Must be called at the end of a line (row or column) of modules. A helper function for getPenaltyScore(). private: int finderPenaltyTerminateAndCount(bool currentRunColor, int currentRunLength, std::array<int,7> &runHistory) const; // Pushes the given value to the front and drops the last value. A helper function for getPenaltyScore(). private: void finderPenaltyAddHistory(int currentRunLength, std::array<int,7> &runHistory) const; // 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]; }; /*---- 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); }; /* * An appendable sequence of bits (0s and 1s). Mainly used by QrSegment. */ class BitBuffer final : public std::vector<bool> { /*---- Constructor ----*/ // Creates an empty bit buffer (length 0). public: BitBuffer(); /*---- Method ----*/ // Appends the given number of low-order bits of the given value // to this buffer. Requires 0 <= len <= 31 and val < 2^len. public: void appendBits(std::uint32_t val, int len); }; }