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557 lines
20 KiB
557 lines
20 KiB
/*
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* QR Code generator library (C++)
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*
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* Copyright (c) Project Nayuki. (MIT License)
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* https://www.nayuki.io/page/qr-code-generator-library
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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* - The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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* - The Software is provided "as is", without warranty of any kind, express or
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* implied, including but not limited to the warranties of merchantability,
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* fitness for a particular purpose and noninfringement. In no event shall the
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* authors or copyright holders be liable for any claim, damages or other
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* liability, whether in an action of contract, tort or otherwise, arising from,
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* out of or in connection with the Software or the use or other dealings in the
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* Software.
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*/
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#pragma once
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#include <array>
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#include <cstdint>
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#include <stdexcept>
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#include <string>
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#include <vector>
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namespace qrcodegen {
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/*
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* A segment of character/binary/control data in a QR Code symbol.
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* Instances of this class are immutable.
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* The mid-level way to create a segment is to take the payload data
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* and call a static factory function such as QrSegment::makeNumeric().
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* The low-level way to create a segment is to custom-make the bit buffer
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* and call the QrSegment() constructor with appropriate values.
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* This segment class imposes no length restrictions, but QR Codes have restrictions.
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* Even in the most favorable conditions, a QR Code can only hold 7089 characters of data.
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* Any segment longer than this is meaningless for the purpose of generating QR Codes.
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*/
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class QrSegment final {
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/*---- Public helper enumeration ----*/
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/*
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* Describes how a segment's data bits are interpreted. Immutable.
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*/
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public: class Mode final {
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/*-- Constants --*/
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public: static const Mode NUMERIC;
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public: static const Mode ALPHANUMERIC;
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public: static const Mode BYTE;
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public: static const Mode KANJI;
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public: static const Mode ECI;
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/*-- Fields --*/
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// The mode indicator bits, which is a uint4 value (range 0 to 15).
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private: int modeBits;
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// Number of character count bits for three different version ranges.
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private: int numBitsCharCount[3];
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/*-- Constructor --*/
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private: Mode(int mode, int cc0, int cc1, int cc2);
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/*-- Methods --*/
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/*
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* (Package-private) Returns the mode indicator bits, which is an unsigned 4-bit value (range 0 to 15).
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*/
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public: int getModeBits() const;
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/*
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* (Package-private) Returns the bit width of the character count field for a segment in
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* this mode in a QR Code at the given version number. The result is in the range [0, 16].
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*/
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public: int numCharCountBits(int ver) const;
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};
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/*---- Static factory functions (mid level) ----*/
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/*
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* Returns a segment representing the given binary data encoded in
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* byte mode. All input byte vectors are acceptable. Any text string
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* can be converted to UTF-8 bytes and encoded as a byte mode segment.
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*/
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public: static QrSegment makeBytes(const std::vector<std::uint8_t> &data);
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/*
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* Returns a segment representing the given string of decimal digits encoded in numeric mode.
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*/
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public: static QrSegment makeNumeric(const char *digits);
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/*
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* Returns a segment representing the given text string encoded in alphanumeric mode.
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* The characters allowed are: 0 to 9, A to Z (uppercase only), space,
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* dollar, percent, asterisk, plus, hyphen, period, slash, colon.
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*/
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public: static QrSegment makeAlphanumeric(const char *text);
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/*
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* Returns a list of zero or more segments to represent the given text string. The result
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* may use various segment modes and switch modes to optimize the length of the bit stream.
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*/
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public: static std::vector<QrSegment> makeSegments(const char *text);
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/*
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* Returns a segment representing an Extended Channel Interpretation
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* (ECI) designator with the given assignment value.
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*/
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public: static QrSegment makeEci(long assignVal);
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/*---- Public static helper functions ----*/
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/*
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* Tests whether the given string can be encoded as a segment in alphanumeric mode.
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* A string is encodable iff each character is in the following set: 0 to 9, A to Z
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* (uppercase only), space, dollar, percent, asterisk, plus, hyphen, period, slash, colon.
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*/
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public: static bool isAlphanumeric(const char *text);
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/*
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* Tests whether the given string can be encoded as a segment in numeric mode.
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* A string is encodable iff each character is in the range 0 to 9.
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*/
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public: static bool isNumeric(const char *text);
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/*---- Instance fields ----*/
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/* The mode indicator of this segment. Accessed through getMode(). */
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private: Mode mode;
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/* The length of this segment's unencoded data. Measured in characters for
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* numeric/alphanumeric/kanji mode, bytes for byte mode, and 0 for ECI mode.
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* Always zero or positive. Not the same as the data's bit length.
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* Accessed through getNumChars(). */
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private: int numChars;
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/* The data bits of this segment. Accessed through getData(). */
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private: std::vector<bool> data;
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/*---- Constructors (low level) ----*/
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/*
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* Creates a new QR Code segment with the given attributes and data.
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* The character count (numCh) must agree with the mode and the bit buffer length,
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* but the constraint isn't checked. The given bit buffer is copied and stored.
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*/
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public: QrSegment(Mode md, int numCh, const std::vector<bool> &dt);
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/*
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* Creates a new QR Code segment with the given parameters and data.
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* The character count (numCh) must agree with the mode and the bit buffer length,
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* but the constraint isn't checked. The given bit buffer is moved and stored.
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*/
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public: QrSegment(Mode md, int numCh, std::vector<bool> &&dt);
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/*---- Methods ----*/
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/*
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* Returns the mode field of this segment.
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*/
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public: Mode getMode() const;
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/*
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* Returns the character count field of this segment.
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*/
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public: int getNumChars() const;
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/*
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* Returns the data bits of this segment.
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*/
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public: const std::vector<bool> &getData() const;
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// (Package-private) Calculates the number of bits needed to encode the given segments at
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// the given version. Returns a non-negative number if successful. Otherwise returns -1 if a
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// segment has too many characters to fit its length field, or the total bits exceeds INT_MAX.
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public: static int getTotalBits(const std::vector<QrSegment> &segs, int version);
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/*---- Private constant ----*/
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/* The set of all legal characters in alphanumeric mode, where
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* each character value maps to the index in the string. */
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private: static const char *ALPHANUMERIC_CHARSET;
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};
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/*
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* A QR Code symbol, which is a type of two-dimension barcode.
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* Invented by Denso Wave and described in the ISO/IEC 18004 standard.
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* Instances of this class represent an immutable square grid of black and white cells.
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* The class provides static factory functions to create a QR Code from text or binary data.
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* The class covers the QR Code Model 2 specification, supporting all versions (sizes)
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* from 1 to 40, all 4 error correction levels, and 4 character encoding modes.
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*
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* Ways to create a QR Code object:
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* - High level: Take the payload data and call QrCode::encodeText() or QrCode::encodeBinary().
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* - Mid level: Custom-make the list of segments and call QrCode::encodeSegments().
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* - Low level: Custom-make the array of data codeword bytes (including
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* segment headers and final padding, excluding error correction codewords),
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* supply the appropriate version number, and call the QrCode() constructor.
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* (Note that all ways require supplying the desired error correction level.)
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*/
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class QrCode final {
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/*---- Public helper enumeration ----*/
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/*
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* The error correction level in a QR Code symbol.
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*/
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public: enum class Ecc {
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LOW = 0 , // The QR Code can tolerate about 7% erroneous codewords
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MEDIUM , // The QR Code can tolerate about 15% erroneous codewords
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QUARTILE, // The QR Code can tolerate about 25% erroneous codewords
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HIGH , // The QR Code can tolerate about 30% erroneous codewords
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};
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// Returns a value in the range 0 to 3 (unsigned 2-bit integer).
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private: static int getFormatBits(Ecc ecl);
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/*---- Static factory functions (high level) ----*/
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/*
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* Returns a QR Code representing the given Unicode text string at the given error correction level.
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* As a conservative upper bound, this function is guaranteed to succeed for strings that have 2953 or fewer
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* UTF-8 code units (not Unicode code points) if the low error correction level is used. The smallest possible
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* QR Code version is automatically chosen for the output. The ECC level of the result may be higher than
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* the ecl argument if it can be done without increasing the version.
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*/
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public: static QrCode encodeText(const char *text, Ecc ecl);
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/*
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* Returns a QR Code representing the given binary data at the given error correction level.
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* This function always encodes using the binary segment mode, not any text mode. The maximum number of
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* bytes allowed is 2953. The smallest possible QR Code version is automatically chosen for the output.
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* The ECC level of the result may be higher than the ecl argument if it can be done without increasing the version.
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*/
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public: static QrCode encodeBinary(const std::vector<std::uint8_t> &data, Ecc ecl);
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/*---- Static factory functions (mid level) ----*/
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/*
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* Returns a QR Code representing the given segments with the given encoding parameters.
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* The smallest possible QR Code version within the given range is automatically
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* chosen for the output. Iff boostEcl is true, then the ECC level of the result
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* may be higher than the ecl argument if it can be done without increasing the
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* version. The mask number is either between 0 to 7 (inclusive) to force that
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* mask, or -1 to automatically choose an appropriate mask (which may be slow).
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* This function allows the user to create a custom sequence of segments that switches
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* between modes (such as alphanumeric and byte) to encode text in less space.
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* This is a mid-level API; the high-level API is encodeText() and encodeBinary().
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*/
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public: static QrCode encodeSegments(const std::vector<QrSegment> &segs, Ecc ecl,
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int minVersion=1, int maxVersion=40, int mask=-1, bool boostEcl=true); // All optional parameters
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/*---- Instance fields ----*/
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// Immutable scalar parameters:
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/* The version number of this QR Code, which is between 1 and 40 (inclusive).
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* This determines the size of this barcode. */
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private: int version;
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/* The width and height of this QR Code, measured in modules, between
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* 21 and 177 (inclusive). This is equal to version * 4 + 17. */
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private: int size;
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/* The error correction level used in this QR Code. */
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private: Ecc errorCorrectionLevel;
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/* The index of the mask pattern used in this QR Code, which is between 0 and 7 (inclusive).
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* Even if a QR Code is created with automatic masking requested (mask = -1),
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* the resulting object still has a mask value between 0 and 7. */
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private: int mask;
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// Private grids of modules/pixels, with dimensions of size*size:
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// The modules of this QR Code (false = white, true = black).
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// Immutable after constructor finishes. Accessed through getModule().
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private: std::vector<std::vector<bool> > modules;
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// Indicates function modules that are not subjected to masking. Discarded when constructor finishes.
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private: std::vector<std::vector<bool> > isFunction;
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/*---- Constructor (low level) ----*/
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/*
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* Creates a new QR Code with the given version number,
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* error correction level, data codeword bytes, and mask number.
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* This is a low-level API that most users should not use directly.
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* A mid-level API is the encodeSegments() function.
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*/
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public: QrCode(int ver, Ecc ecl, const std::vector<std::uint8_t> &dataCodewords, int msk);
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/*---- Public instance methods ----*/
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/*
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* Returns this QR Code's version, in the range [1, 40].
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*/
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public: int getVersion() const;
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/*
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* Returns this QR Code's size, in the range [21, 177].
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*/
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public: int getSize() const;
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/*
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* Returns this QR Code's error correction level.
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*/
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public: Ecc getErrorCorrectionLevel() const;
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/*
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* Returns this QR Code's mask, in the range [0, 7].
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*/
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public: int getMask() const;
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/*
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* Returns the color of the module (pixel) at the given coordinates, which is false
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* for white or true for black. The top left corner has the coordinates (x=0, y=0).
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* If the given coordinates are out of bounds, then false (white) is returned.
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*/
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public: bool getModule(int x, int y) const;
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/*
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* Returns a string of SVG code for an image depicting this QR Code, with the given number
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* of border modules. The string always uses Unix newlines (\n), regardless of the platform.
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*/
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public: std::string toSvgString(int border) const;
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/*---- Private helper methods for constructor: Drawing function modules ----*/
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// Reads this object's version field, and draws and marks all function modules.
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private: void drawFunctionPatterns();
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// Draws two copies of the format bits (with its own error correction code)
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// based on the given mask and this object's error correction level field.
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private: void drawFormatBits(int msk);
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// Draws two copies of the version bits (with its own error correction code),
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// based on this object's version field, iff 7 <= version <= 40.
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private: void drawVersion();
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// Draws a 9*9 finder pattern including the border separator,
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// with the center module at (x, y). Modules can be out of bounds.
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private: void drawFinderPattern(int x, int y);
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// Draws a 5*5 alignment pattern, with the center module
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// at (x, y). All modules must be in bounds.
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private: void drawAlignmentPattern(int x, int y);
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// Sets the color of a module and marks it as a function module.
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// Only used by the constructor. Coordinates must be in bounds.
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private: void setFunctionModule(int x, int y, bool isBlack);
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// Returns the color of the module at the given coordinates, which must be in range.
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private: bool module(int x, int y) const;
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/*---- Private helper methods for constructor: Codewords and masking ----*/
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// Returns a new byte string representing the given data with the appropriate error correction
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// codewords appended to it, based on this object's version and error correction level.
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private: std::vector<std::uint8_t> addEccAndInterleave(const std::vector<std::uint8_t> &data) const;
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// Draws the given sequence of 8-bit codewords (data and error correction) onto the entire
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// data area of this QR Code. Function modules need to be marked off before this is called.
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private: void drawCodewords(const std::vector<std::uint8_t> &data);
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// XORs the codeword modules in this QR Code with the given mask pattern.
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// The function modules must be marked and the codeword bits must be drawn
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// before masking. Due to the arithmetic of XOR, calling applyMask() with
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// the same mask value a second time will undo the mask. A final well-formed
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// QR Code needs exactly one (not zero, two, etc.) mask applied.
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private: void applyMask(int msk);
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// Calculates and returns the penalty score based on state of this QR Code's current modules.
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// This is used by the automatic mask choice algorithm to find the mask pattern that yields the lowest score.
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private: long getPenaltyScore() const;
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/*---- Private helper functions ----*/
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// Returns an ascending list of positions of alignment patterns for this version number.
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// Each position is in the range [0,177), and are used on both the x and y axes.
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// This could be implemented as lookup table of 40 variable-length lists of unsigned bytes.
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private: std::vector<int> getAlignmentPatternPositions() const;
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// Returns the number of data bits that can be stored in a QR Code of the given version number, after
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// all function modules are excluded. This includes remainder bits, so it might not be a multiple of 8.
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// The result is in the range [208, 29648]. This could be implemented as a 40-entry lookup table.
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private: static int getNumRawDataModules(int ver);
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// Returns the number of 8-bit data (i.e. not error correction) codewords contained in any
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// QR Code of the given version number and error correction level, with remainder bits discarded.
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// This stateless pure function could be implemented as a (40*4)-cell lookup table.
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private: static int getNumDataCodewords(int ver, Ecc ecl);
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// Returns a Reed-Solomon ECC generator polynomial for the given degree. This could be
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// implemented as a lookup table over all possible parameter values, instead of as an algorithm.
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private: static std::vector<std::uint8_t> reedSolomonComputeDivisor(int degree);
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// Returns the Reed-Solomon error correction codeword for the given data and divisor polynomials.
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private: static std::vector<std::uint8_t> reedSolomonComputeRemainder(const std::vector<std::uint8_t> &data, const std::vector<std::uint8_t> &divisor);
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// Returns the product of the two given field elements modulo GF(2^8/0x11D).
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// All inputs are valid. This could be implemented as a 256*256 lookup table.
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private: static std::uint8_t reedSolomonMultiply(std::uint8_t x, std::uint8_t y);
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// Can only be called immediately after a white run is added, and
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// returns either 0, 1, or 2. A helper function for getPenaltyScore().
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private: int finderPenaltyCountPatterns(const std::array<int,7> &runHistory) const;
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// Must be called at the end of a line (row or column) of modules. A helper function for getPenaltyScore().
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private: int finderPenaltyTerminateAndCount(bool currentRunColor, int currentRunLength, std::array<int,7> &runHistory) const;
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// Pushes the given value to the front and drops the last value. A helper function for getPenaltyScore().
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private: void finderPenaltyAddHistory(int currentRunLength, std::array<int,7> &runHistory) const;
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// Returns true iff the i'th bit of x is set to 1.
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private: static bool getBit(long x, int i);
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/*---- Constants and tables ----*/
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// The minimum version number supported in the QR Code Model 2 standard.
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public: static constexpr int MIN_VERSION = 1;
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// The maximum version number supported in the QR Code Model 2 standard.
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public: static constexpr int MAX_VERSION = 40;
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// For use in getPenaltyScore(), when evaluating which mask is best.
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private: static const int PENALTY_N1;
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private: static const int PENALTY_N2;
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private: static const int PENALTY_N3;
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private: static const int PENALTY_N4;
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private: static const std::int8_t ECC_CODEWORDS_PER_BLOCK[4][41];
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private: static const std::int8_t NUM_ERROR_CORRECTION_BLOCKS[4][41];
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};
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/*---- Public exception class ----*/
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/*
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* Thrown when the supplied data does not fit any QR Code version. Ways to handle this exception include:
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* - Decrease the error correction level if it was greater than Ecc::LOW.
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* - If the encodeSegments() function was called with a maxVersion argument, then increase
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* it if it was less than QrCode::MAX_VERSION. (This advice does not apply to the other
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* factory functions because they search all versions up to QrCode::MAX_VERSION.)
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* - Split the text data into better or optimal segments in order to reduce the number of bits required.
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* - Change the text or binary data to be shorter.
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* - Change the text to fit the character set of a particular segment mode (e.g. alphanumeric).
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* - Propagate the error upward to the caller/user.
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*/
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class data_too_long : public std::length_error {
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public: explicit data_too_long(const std::string &msg);
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};
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/*
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* An appendable sequence of bits (0s and 1s). Mainly used by QrSegment.
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*/
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class BitBuffer final : public std::vector<bool> {
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/*---- Constructor ----*/
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// Creates an empty bit buffer (length 0).
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public: BitBuffer();
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/*---- Method ----*/
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// Appends the given number of low-order bits of the given value
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// to this buffer. Requires 0 <= len <= 31 and val < 2^len.
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public: void appendBits(std::uint32_t val, int len);
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};
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}
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