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 <stdbool.h> 27 #include <stddef.h> 28 #include <stdint.h> 29 30 31 #ifdef __cplusplus 32 extern "C" { 33 #endif 34 35 36 /* 37 * This library creates QR Code symbols, which is a type of two-dimension barcode. 38 * Invented by Denso Wave and described in the ISO/IEC 18004 standard. 39 * A QR Code structure is an immutable square grid of black and white cells. 40 * The library provides functions to create a QR Code from text or binary data. 41 * The library covers the QR Code Model 2 specification, supporting all versions (sizes) 42 * from 1 to 40, all 4 error correction levels, and 4 character encoding modes. 43 * 44 * Ways to create a QR Code object: 45 * - High level: Take the payload data and call qrcodegen_encodeText() or qrcodegen_encodeBinary(). 46 * - Low level: Custom-make the list of segments and call 47 * qrcodegen_encodeSegments() or qrcodegen_encodeSegmentsAdvanced(). 48 * (Note that all ways require supplying the desired error correction level and various byte buffers.) 49 */ 50 51 52 /*---- Enum and struct types----*/ 53 54 /* 55 * The error correction level in a QR Code symbol. 56 */ 57 enum qrcodegen_Ecc { 58 // Must be declared in ascending order of error protection 59 // so that an internal qrcodegen function works properly 60 qrcodegen_Ecc_LOW = 0 , // The QR Code can tolerate about 7% erroneous codewords 61 qrcodegen_Ecc_MEDIUM , // The QR Code can tolerate about 15% erroneous codewords 62 qrcodegen_Ecc_QUARTILE, // The QR Code can tolerate about 25% erroneous codewords 63 qrcodegen_Ecc_HIGH , // The QR Code can tolerate about 30% erroneous codewords 64 }; 65 66 67 /* 68 * The mask pattern used in a QR Code symbol. 69 */ 70 enum qrcodegen_Mask { 71 // A special value to tell the QR Code encoder to 72 // automatically select an appropriate mask pattern 73 qrcodegen_Mask_AUTO = -1, 74 // The eight actual mask patterns 75 qrcodegen_Mask_0 = 0, 76 qrcodegen_Mask_1, 77 qrcodegen_Mask_2, 78 qrcodegen_Mask_3, 79 qrcodegen_Mask_4, 80 qrcodegen_Mask_5, 81 qrcodegen_Mask_6, 82 qrcodegen_Mask_7, 83 }; 84 85 86 /* 87 * Describes how a segment's data bits are interpreted. 88 */ 89 enum qrcodegen_Mode { 90 qrcodegen_Mode_NUMERIC = 0x1, 91 qrcodegen_Mode_ALPHANUMERIC = 0x2, 92 qrcodegen_Mode_BYTE = 0x4, 93 qrcodegen_Mode_KANJI = 0x8, 94 qrcodegen_Mode_ECI = 0x7, 95 }; 96 97 98 /* 99 * A segment of character/binary/control data in a QR Code symbol. 100 * The mid-level way to create a segment is to take the payload data 101 * and call a factory function such as qrcodegen_makeNumeric(). 102 * The low-level way to create a segment is to custom-make the bit buffer 103 * and initialize a qrcodegen_Segment struct with appropriate values. 104 * Even in the most favorable conditions, a QR Code can only hold 7089 characters of data. 105 * Any segment longer than this is meaningless for the purpose of generating QR Codes. 106 * Moreover, the maximum allowed bit length is 32767 because 107 * the largest QR Code (version 40) has 31329 modules. 108 */ 109 struct qrcodegen_Segment { 110 // The mode indicator of this segment. 111 enum qrcodegen_Mode mode; 112 113 // The length of this segment's unencoded data. Measured in characters for 114 // numeric/alphanumeric/kanji mode, bytes for byte mode, and 0 for ECI mode. 115 // Always zero or positive. Not the same as the data's bit length. 116 int numChars; 117 118 // The data bits of this segment, packed in bitwise big endian. 119 // Can be null if the bit length is zero. 120 uint8_t *data; 121 122 // The number of valid data bits used in the buffer. Requires 123 // 0 <= bitLength <= 32767, and bitLength <= (capacity of data array) * 8. 124 // The character count (numChars) must agree with the mode and the bit buffer length. 125 int bitLength; 126 }; 127 128 129 130 /*---- Macro constants and functions ----*/ 131 132 #define qrcodegen_VERSION_MIN 1 // The minimum version number supported in the QR Code Model 2 standard 133 #define qrcodegen_VERSION_MAX 40 // The maximum version number supported in the QR Code Model 2 standard 134 135 // Calculates the number of bytes needed to store any QR Code up to and including the given version number, 136 // as a compile-time constant. For example, 'uint8_t buffer[qrcodegen_BUFFER_LEN_FOR_VERSION(25)];' 137 // can store any single QR Code from version 1 to 25 (inclusive). The result fits in an int (or int16). 138 // Requires qrcodegen_VERSION_MIN <= n <= qrcodegen_VERSION_MAX. 139 #define qrcodegen_BUFFER_LEN_FOR_VERSION(n) ((((n) * 4 + 17) * ((n) * 4 + 17) + 7) / 8 + 1) 140 141 // The worst-case number of bytes needed to store one QR Code, up to and including 142 // version 40. This value equals 3918, which is just under 4 kilobytes. 143 // Use this more convenient value to avoid calculating tighter memory bounds for buffers. 144 #define qrcodegen_BUFFER_LEN_MAX qrcodegen_BUFFER_LEN_FOR_VERSION(qrcodegen_VERSION_MAX) 145 146 147 148 /*---- Functions (high level) to generate QR Codes ----*/ 149 150 /* 151 * Encodes the given text string to a QR Code, returning true if encoding succeeded. 152 * If the data is too long to fit in any version in the given range 153 * at the given ECC level, then false is returned. 154 * - The input text must be encoded in UTF-8 and contain no NULs. 155 * - The variables ecl and mask must correspond to enum constant values. 156 * - Requires 1 <= minVersion <= maxVersion <= 40. 157 * - The arrays tempBuffer and qrcode must each have a length 158 * of at least qrcodegen_BUFFER_LEN_FOR_VERSION(maxVersion). 159 * - After the function returns, tempBuffer contains no useful data. 160 * - If successful, the resulting QR Code may use numeric, 161 * alphanumeric, or byte mode to encode the text. 162 * - In the most optimistic case, a QR Code at version 40 with low ECC 163 * can hold any UTF-8 string up to 2953 bytes, or any alphanumeric string 164 * up to 4296 characters, or any digit string up to 7089 characters. 165 * These numbers represent the hard upper limit of the QR Code standard. 166 * - Please consult the QR Code specification for information on 167 * data capacities per version, ECC level, and text encoding mode. 168 */ 169 bool qrcodegen_encodeText(const char *text, uint8_t tempBuffer[], uint8_t qrcode[], 170 enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl); 171 172 173 /* 174 * Encodes the given binary data to a QR Code, returning true if encoding succeeded. 175 * If the data is too long to fit in any version in the given range 176 * at the given ECC level, then false is returned. 177 * - The input array range dataAndTemp[0 : dataLen] should normally be 178 * valid UTF-8 text, but is not required by the QR Code standard. 179 * - The variables ecl and mask must correspond to enum constant values. 180 * - Requires 1 <= minVersion <= maxVersion <= 40. 181 * - The arrays dataAndTemp and qrcode must each have a length 182 * of at least qrcodegen_BUFFER_LEN_FOR_VERSION(maxVersion). 183 * - After the function returns, the contents of dataAndTemp may have changed, 184 * and does not represent useful data anymore. 185 * - If successful, the resulting QR Code will use byte mode to encode the data. 186 * - In the most optimistic case, a QR Code at version 40 with low ECC can hold any byte 187 * sequence up to length 2953. This is the hard upper limit of the QR Code standard. 188 * - Please consult the QR Code specification for information on 189 * data capacities per version, ECC level, and text encoding mode. 190 */ 191 bool qrcodegen_encodeBinary(uint8_t dataAndTemp[], size_t dataLen, uint8_t qrcode[], 192 enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl); 193 194 195 /*---- Functions (low level) to generate QR Codes ----*/ 196 197 /* 198 * Renders a QR Code representing the given segments at the given error correction level. 199 * The smallest possible QR Code version is automatically chosen for the output. Returns true if 200 * QR Code creation succeeded, or false if the data is too long to fit in any version. The ECC level 201 * of the result may be higher than the ecl argument if it can be done without increasing the version. 202 * This function allows the user to create a custom sequence of segments that switches 203 * between modes (such as alphanumeric and byte) to encode text in less space. 204 * This is a low-level API; the high-level API is qrcodegen_encodeText() and qrcodegen_encodeBinary(). 205 * To save memory, the segments' data buffers can alias/overlap tempBuffer, and will 206 * result in them being clobbered, but the QR Code output will still be correct. 207 * But the qrcode array must not overlap tempBuffer or any segment's data buffer. 208 */ 209 bool qrcodegen_encodeSegments(const struct qrcodegen_Segment segs[], size_t len, 210 enum qrcodegen_Ecc ecl, uint8_t tempBuffer[], uint8_t qrcode[]); 211 212 213 /* 214 * Renders a QR Code representing the given segments with the given encoding parameters. 215 * Returns true if QR Code creation succeeded, or false if the data is too long to fit in the range of versions. 216 * The smallest possible QR Code version within the given range is automatically 217 * chosen for the output. Iff boostEcl is true, then the ECC level of the result 218 * may be higher than the ecl argument if it can be done without increasing the 219 * version. The mask is either between qrcodegen_Mask_0 to 7 to force that mask, or 220 * qrcodegen_Mask_AUTO to automatically choose an appropriate mask (which may be slow). 221 * This function allows the user to create a custom sequence of segments that switches 222 * between modes (such as alphanumeric and byte) to encode text in less space. 223 * This is a low-level API; the high-level API is qrcodegen_encodeText() and qrcodegen_encodeBinary(). 224 * To save memory, the segments' data buffers can alias/overlap tempBuffer, and will 225 * result in them being clobbered, but the QR Code output will still be correct. 226 * But the qrcode array must not overlap tempBuffer or any segment's data buffer. 227 */ 228 bool qrcodegen_encodeSegmentsAdvanced(const struct qrcodegen_Segment segs[], size_t len, enum qrcodegen_Ecc ecl, 229 int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl, uint8_t tempBuffer[], uint8_t qrcode[]); 230 231 232 /* 233 * Tests whether the given string can be encoded as a segment in alphanumeric mode. 234 * A string is encodable iff each character is in the following set: 0 to 9, A to Z 235 * (uppercase only), space, dollar, percent, asterisk, plus, hyphen, period, slash, colon. 236 */ 237 bool qrcodegen_isAlphanumeric(const char *text); 238 239 240 /* 241 * Tests whether the given string can be encoded as a segment in numeric mode. 242 * A string is encodable iff each character is in the range 0 to 9. 243 */ 244 bool qrcodegen_isNumeric(const char *text); 245 246 247 /* 248 * Returns the number of bytes (uint8_t) needed for the data buffer of a segment 249 * containing the given number of characters using the given mode. Notes: 250 * - Returns SIZE_MAX on failure, i.e. numChars > INT16_MAX or 251 * the number of needed bits exceeds INT16_MAX (i.e. 32767). 252 * - Otherwise, all valid results are in the range [0, ceil(INT16_MAX / 8)], i.e. at most 4096. 253 * - It is okay for the user to allocate more bytes for the buffer than needed. 254 * - For byte mode, numChars measures the number of bytes, not Unicode code points. 255 * - For ECI mode, numChars must be 0, and the worst-case number of bytes is returned. 256 * An actual ECI segment can have shorter data. For non-ECI modes, the result is exact. 257 */ 258 size_t qrcodegen_calcSegmentBufferSize(enum qrcodegen_Mode mode, size_t numChars); 259 260 261 /* 262 * Returns a segment representing the given binary data encoded in 263 * byte mode. All input byte arrays are acceptable. Any text string 264 * can be converted to UTF-8 bytes and encoded as a byte mode segment. 265 */ 266 struct qrcodegen_Segment qrcodegen_makeBytes(const uint8_t data[], size_t len, uint8_t buf[]); 267 268 269 /* 270 * Returns a segment representing the given string of decimal digits encoded in numeric mode. 271 */ 272 struct qrcodegen_Segment qrcodegen_makeNumeric(const char *digits, uint8_t buf[]); 273 274 275 /* 276 * Returns a segment representing the given text string encoded in alphanumeric mode. 277 * The characters allowed are: 0 to 9, A to Z (uppercase only), space, 278 * dollar, percent, asterisk, plus, hyphen, period, slash, colon. 279 */ 280 struct qrcodegen_Segment qrcodegen_makeAlphanumeric(const char *text, uint8_t buf[]); 281 282 283 /* 284 * Returns a segment representing an Extended Channel Interpretation 285 * (ECI) designator with the given assignment value. 286 */ 287 struct qrcodegen_Segment qrcodegen_makeEci(long assignVal, uint8_t buf[]); 288 289 290 /*---- Functions to extract raw data from QR Codes ----*/ 291 292 /* 293 * Returns the side length of the given QR Code, assuming that encoding succeeded. 294 * The result is in the range [21, 177]. Note that the length of the array buffer 295 * is related to the side length - every 'uint8_t qrcode[]' must have length at least 296 * qrcodegen_BUFFER_LEN_FOR_VERSION(version), which equals ceil(size^2 / 8 + 1). 297 */ 298 int qrcodegen_getSize(const uint8_t qrcode[]); 299 300 301 /* 302 * Returns the color of the module (pixel) at the given coordinates, which is false 303 * for white or true for black. The top left corner has the coordinates (x=0, y=0). 304 * If the given coordinates are out of bounds, then false (white) is returned. 305 */ 306 bool qrcodegen_getModule(const uint8_t qrcode[], int x, int y); 307 308 309 #ifdef __cplusplus 310 } 311 #endif 312
