BitArray.php
8 months ago
BitMatrix.php
8 months ago
BitUtils.php
8 months ago
CharacterSetEci.php
8 months ago
EcBlock.php
8 months ago
EcBlocks.php
8 months ago
ErrorCorrectionLevel.php
8 months ago
FormatInformation.php
8 months ago
Mode.php
8 months ago
ReedSolomonCodec.php
8 months ago
Version.php
8 months ago
FormatInformation.php
204 lines
| 1 | <?php |
| 2 | /** |
| 3 | * BaconQrCode |
| 4 | * |
| 5 | * @link http://github.com/Bacon/BaconQrCode For the canonical source repository |
| 6 | * @copyright 2013 Ben 'DASPRiD' Scholzen |
| 7 | * @license http://opensource.org/licenses/BSD-2-Clause Simplified BSD License |
| 8 | */ |
| 9 | |
| 10 | namespace BaconQrCode\Common; |
| 11 | |
| 12 | /** |
| 13 | * Encapsulates a QR Code's format information, including the data mask used and error correction level. |
| 14 | */ |
| 15 | class FormatInformation |
| 16 | { |
| 17 | /** |
| 18 | * Mask for format information. |
| 19 | */ |
| 20 | private const FORMAT_INFO_MASK_QR = 0x5412; |
| 21 | |
| 22 | /** |
| 23 | * Lookup table for decoding format information. |
| 24 | * |
| 25 | * See ISO 18004:2006, Annex C, Table C.1 |
| 26 | */ |
| 27 | private const FORMAT_INFO_DECODE_LOOKUP = [ |
| 28 | [0x5412, 0x00], |
| 29 | [0x5125, 0x01], |
| 30 | [0x5e7c, 0x02], |
| 31 | [0x5b4b, 0x03], |
| 32 | [0x45f9, 0x04], |
| 33 | [0x40ce, 0x05], |
| 34 | [0x4f97, 0x06], |
| 35 | [0x4aa0, 0x07], |
| 36 | [0x77c4, 0x08], |
| 37 | [0x72f3, 0x09], |
| 38 | [0x7daa, 0x0a], |
| 39 | [0x789d, 0x0b], |
| 40 | [0x662f, 0x0c], |
| 41 | [0x6318, 0x0d], |
| 42 | [0x6c41, 0x0e], |
| 43 | [0x6976, 0x0f], |
| 44 | [0x1689, 0x10], |
| 45 | [0x13be, 0x11], |
| 46 | [0x1ce7, 0x12], |
| 47 | [0x19d0, 0x13], |
| 48 | [0x0762, 0x14], |
| 49 | [0x0255, 0x15], |
| 50 | [0x0d0c, 0x16], |
| 51 | [0x083b, 0x17], |
| 52 | [0x355f, 0x18], |
| 53 | [0x3068, 0x19], |
| 54 | [0x3f31, 0x1a], |
| 55 | [0x3a06, 0x1b], |
| 56 | [0x24b4, 0x1c], |
| 57 | [0x2183, 0x1d], |
| 58 | [0x2eda, 0x1e], |
| 59 | [0x2bed, 0x1f], |
| 60 | ]; |
| 61 | |
| 62 | /** |
| 63 | * Offset i holds the number of 1 bits in the binary representation of i. |
| 64 | * |
| 65 | * @var int[] |
| 66 | */ |
| 67 | private const BITS_SET_IN_HALF_BYTE = [0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4]; |
| 68 | |
| 69 | /** |
| 70 | * Error correction level. |
| 71 | * |
| 72 | * @var ErrorCorrectionLevel |
| 73 | */ |
| 74 | private $ecLevel; |
| 75 | |
| 76 | /** |
| 77 | * Data mask. |
| 78 | * |
| 79 | * @var int |
| 80 | */ |
| 81 | private $dataMask; |
| 82 | |
| 83 | protected function __construct(int $formatInfo) |
| 84 | { |
| 85 | $this->ecLevel = ErrorCorrectionLevel::forBits(($formatInfo >> 3) & 0x3); |
| 86 | $this->dataMask = $formatInfo & 0x7; |
| 87 | } |
| 88 | |
| 89 | /** |
| 90 | * Checks how many bits are different between two integers. |
| 91 | */ |
| 92 | public static function numBitsDiffering(int $a, int $b) : int |
| 93 | { |
| 94 | $a ^= $b; |
| 95 | |
| 96 | return ( |
| 97 | self::BITS_SET_IN_HALF_BYTE[$a & 0xf] |
| 98 | + self::BITS_SET_IN_HALF_BYTE[(BitUtils::unsignedRightShift($a, 4) & 0xf)] |
| 99 | + self::BITS_SET_IN_HALF_BYTE[(BitUtils::unsignedRightShift($a, 8) & 0xf)] |
| 100 | + self::BITS_SET_IN_HALF_BYTE[(BitUtils::unsignedRightShift($a, 12) & 0xf)] |
| 101 | + self::BITS_SET_IN_HALF_BYTE[(BitUtils::unsignedRightShift($a, 16) & 0xf)] |
| 102 | + self::BITS_SET_IN_HALF_BYTE[(BitUtils::unsignedRightShift($a, 20) & 0xf)] |
| 103 | + self::BITS_SET_IN_HALF_BYTE[(BitUtils::unsignedRightShift($a, 24) & 0xf)] |
| 104 | + self::BITS_SET_IN_HALF_BYTE[(BitUtils::unsignedRightShift($a, 28) & 0xf)] |
| 105 | ); |
| 106 | } |
| 107 | |
| 108 | /** |
| 109 | * Decodes format information. |
| 110 | */ |
| 111 | public static function decodeFormatInformation(int $maskedFormatInfo1, int $maskedFormatInfo2) : ?self |
| 112 | { |
| 113 | $formatInfo = self::doDecodeFormatInformation($maskedFormatInfo1, $maskedFormatInfo2); |
| 114 | |
| 115 | if (null !== $formatInfo) { |
| 116 | return $formatInfo; |
| 117 | } |
| 118 | |
| 119 | // Should return null, but, some QR codes apparently do not mask this info. Try again by actually masking the |
| 120 | // pattern first. |
| 121 | return self::doDecodeFormatInformation( |
| 122 | $maskedFormatInfo1 ^ self::FORMAT_INFO_MASK_QR, |
| 123 | $maskedFormatInfo2 ^ self::FORMAT_INFO_MASK_QR |
| 124 | ); |
| 125 | } |
| 126 | |
| 127 | /** |
| 128 | * Internal method for decoding format information. |
| 129 | */ |
| 130 | private static function doDecodeFormatInformation(int $maskedFormatInfo1, int $maskedFormatInfo2) : ?self |
| 131 | { |
| 132 | $bestDifference = PHP_INT_MAX; |
| 133 | $bestFormatInfo = 0; |
| 134 | |
| 135 | foreach (self::FORMAT_INFO_DECODE_LOOKUP as $decodeInfo) { |
| 136 | $targetInfo = $decodeInfo[0]; |
| 137 | |
| 138 | if ($targetInfo === $maskedFormatInfo1 || $targetInfo === $maskedFormatInfo2) { |
| 139 | // Found an exact match |
| 140 | return new self($decodeInfo[1]); |
| 141 | } |
| 142 | |
| 143 | $bitsDifference = self::numBitsDiffering($maskedFormatInfo1, $targetInfo); |
| 144 | |
| 145 | if ($bitsDifference < $bestDifference) { |
| 146 | $bestFormatInfo = $decodeInfo[1]; |
| 147 | $bestDifference = $bitsDifference; |
| 148 | } |
| 149 | |
| 150 | if ($maskedFormatInfo1 !== $maskedFormatInfo2) { |
| 151 | // Also try the other option |
| 152 | $bitsDifference = self::numBitsDiffering($maskedFormatInfo2, $targetInfo); |
| 153 | |
| 154 | if ($bitsDifference < $bestDifference) { |
| 155 | $bestFormatInfo = $decodeInfo[1]; |
| 156 | $bestDifference = $bitsDifference; |
| 157 | } |
| 158 | } |
| 159 | } |
| 160 | |
| 161 | // Hamming distance of the 32 masked codes is 7, by construction, so <= 3 bits differing means we found a match. |
| 162 | if ($bestDifference <= 3) { |
| 163 | return new self($bestFormatInfo); |
| 164 | } |
| 165 | |
| 166 | return null; |
| 167 | } |
| 168 | |
| 169 | /** |
| 170 | * Returns the error correction level. |
| 171 | */ |
| 172 | public function getErrorCorrectionLevel() : ErrorCorrectionLevel |
| 173 | { |
| 174 | return $this->ecLevel; |
| 175 | } |
| 176 | |
| 177 | /** |
| 178 | * Returns the data mask. |
| 179 | */ |
| 180 | public function getDataMask() : int |
| 181 | { |
| 182 | return $this->dataMask; |
| 183 | } |
| 184 | |
| 185 | /** |
| 186 | * Hashes the code of the EC level. |
| 187 | */ |
| 188 | public function hashCode() : int |
| 189 | { |
| 190 | return ($this->ecLevel->getBits() << 3) | $this->dataMask; |
| 191 | } |
| 192 | |
| 193 | /** |
| 194 | * Verifies if this instance equals another one. |
| 195 | */ |
| 196 | public function equals(self $other) : bool |
| 197 | { |
| 198 | return ( |
| 199 | $this->ecLevel === $other->ecLevel |
| 200 | && $this->dataMask === $other->dataMask |
| 201 | ); |
| 202 | } |
| 203 | } |
| 204 |