woocommerce-pos
/
vendor_prefixed
/
chillerlan
/
php-qrcode
/
src
/
Detector
/
FinderPatternFinder.php
FinderPatternFinder.php in WCPOS – Point of Sale (POS) plugin for WooCommerce 1.10.20, at vendor_prefixed/chillerlan/php-qrcode/src/Detector/FinderPatternFinder.php
| 1 | <?php |
| 2 | |
| 3 | /** |
| 4 | * Class FinderPatternFinder |
| 5 | * |
| 6 | * @created 17.01.2021 |
| 7 | * @author ZXing Authors |
| 8 | * @author Smiley <[email protected]> |
| 9 | * @copyright 2021 Smiley |
| 10 | * @license Apache-2.0 |
| 11 | * |
| 12 | * @phan-file-suppress PhanTypePossiblyInvalidDimOffset |
| 13 | */ |
| 14 | namespace WCPOS\Vendor\chillerlan\QRCode\Detector; |
| 15 | |
| 16 | use WCPOS\Vendor\chillerlan\QRCode\Decoder\BitMatrix; |
| 17 | use function abs, count, intdiv, usort; |
| 18 | use const PHP_FLOAT_MAX; |
| 19 | /** |
| 20 | * This class attempts to find finder patterns in a QR Code. Finder patterns are the square |
| 21 | * markers at three corners of a QR Code. |
| 22 | * |
| 23 | * This class is thread-safe but not reentrant. Each thread must allocate its own object. |
| 24 | * |
| 25 | * @author Sean Owen |
| 26 | */ |
| 27 | final class FinderPatternFinder |
| 28 | { |
| 29 | private const MIN_SKIP = 2; |
| 30 | private const MAX_MODULES = 177; |
| 31 | // 1 pixel/module times 3 modules/center |
| 32 | private const CENTER_QUORUM = 2; |
| 33 | // support up to version 10 for mobile clients |
| 34 | private BitMatrix $matrix; |
| 35 | /** @var \chillerlan\QRCode\Detector\FinderPattern[] */ |
| 36 | private array $possibleCenters; |
| 37 | private bool $hasSkipped = \false; |
| 38 | /** |
| 39 | * Creates a finder that will search the image for three finder patterns. |
| 40 | * |
| 41 | * @param BitMatrix $matrix image to search |
| 42 | */ |
| 43 | public function __construct(BitMatrix $matrix) |
| 44 | { |
| 45 | $this->matrix = $matrix; |
| 46 | $this->possibleCenters = []; |
| 47 | } |
| 48 | /** |
| 49 | * @return \chillerlan\QRCode\Detector\FinderPattern[] |
| 50 | */ |
| 51 | public function find() : array |
| 52 | { |
| 53 | $dimension = $this->matrix->getSize(); |
| 54 | // We are looking for black/white/black/white/black modules in |
| 55 | // 1:1:3:1:1 ratio; this tracks the number of such modules seen so far |
| 56 | // Let's assume that the maximum version QR Code we support takes up 1/4 the height of the |
| 57 | // image, and then account for the center being 3 modules in size. This gives the smallest |
| 58 | // number of pixels the center could be, so skip this often. |
| 59 | $iSkip = intdiv(3 * $dimension, 4 * self::MAX_MODULES); |
| 60 | if ($iSkip < self::MIN_SKIP) { |
| 61 | $iSkip = self::MIN_SKIP; |
| 62 | } |
| 63 | $done = \false; |
| 64 | for ($i = $iSkip - 1; $i < $dimension && !$done; $i += $iSkip) { |
| 65 | // Get a row of black/white values |
| 66 | $stateCount = $this->getCrossCheckStateCount(); |
| 67 | $currentState = 0; |
| 68 | for ($j = 0; $j < $dimension; $j++) { |
| 69 | // Black pixel |
| 70 | if ($this->matrix->check($j, $i)) { |
| 71 | // Counting white pixels |
| 72 | if (($currentState & 1) === 1) { |
| 73 | $currentState++; |
| 74 | } |
| 75 | $stateCount[$currentState]++; |
| 76 | } else { |
| 77 | // Counting black pixels |
| 78 | if (($currentState & 1) === 0) { |
| 79 | // A winner? |
| 80 | if ($currentState === 4) { |
| 81 | // Yes |
| 82 | if ($this->foundPatternCross($stateCount)) { |
| 83 | $confirmed = $this->handlePossibleCenter($stateCount, $i, $j); |
| 84 | if ($confirmed) { |
| 85 | // Start examining every other line. Checking each line turned out to be too |
| 86 | // expensive and didn't improve performance. |
| 87 | $iSkip = 3; |
| 88 | if ($this->hasSkipped) { |
| 89 | $done = $this->haveMultiplyConfirmedCenters(); |
| 90 | } else { |
| 91 | $rowSkip = $this->findRowSkip(); |
| 92 | if ($rowSkip > $stateCount[2]) { |
| 93 | // Skip rows between row of lower confirmed center |
| 94 | // and top of presumed third confirmed center |
| 95 | // but back up a bit to get a full chance of detecting |
| 96 | // it, entire width of center of finder pattern |
| 97 | // Skip by rowSkip, but back off by $stateCount[2] (size of last center |
| 98 | // of pattern we saw) to be conservative, and also back off by iSkip which |
| 99 | // is about to be re-added |
| 100 | $i += $rowSkip - $stateCount[2] - $iSkip; |
| 101 | $j = $dimension - 1; |
| 102 | } |
| 103 | } |
| 104 | } else { |
| 105 | $stateCount = $this->doShiftCounts2($stateCount); |
| 106 | $currentState = 3; |
| 107 | continue; |
| 108 | } |
| 109 | // Clear state to start looking again |
| 110 | $currentState = 0; |
| 111 | $stateCount = $this->getCrossCheckStateCount(); |
| 112 | } else { |
| 113 | $stateCount = $this->doShiftCounts2($stateCount); |
| 114 | $currentState = 3; |
| 115 | } |
| 116 | } else { |
| 117 | $stateCount[++$currentState]++; |
| 118 | } |
| 119 | } else { |
| 120 | $stateCount[$currentState]++; |
| 121 | } |
| 122 | } |
| 123 | } |
| 124 | if ($this->foundPatternCross($stateCount)) { |
| 125 | $confirmed = $this->handlePossibleCenter($stateCount, $i, $dimension); |
| 126 | if ($confirmed) { |
| 127 | $iSkip = $stateCount[0]; |
| 128 | if ($this->hasSkipped) { |
| 129 | // Found a third one |
| 130 | $done = $this->haveMultiplyConfirmedCenters(); |
| 131 | } |
| 132 | } |
| 133 | } |
| 134 | } |
| 135 | return $this->orderBestPatterns($this->selectBestPatterns()); |
| 136 | } |
| 137 | /** |
| 138 | * @return int[] |
| 139 | */ |
| 140 | private function getCrossCheckStateCount() : array |
| 141 | { |
| 142 | return [0, 0, 0, 0, 0]; |
| 143 | } |
| 144 | /** |
| 145 | * @param int[] $stateCount |
| 146 | * |
| 147 | * @return int[] |
| 148 | */ |
| 149 | private function doShiftCounts2(array $stateCount) : array |
| 150 | { |
| 151 | $stateCount[0] = $stateCount[2]; |
| 152 | $stateCount[1] = $stateCount[3]; |
| 153 | $stateCount[2] = $stateCount[4]; |
| 154 | $stateCount[3] = 1; |
| 155 | $stateCount[4] = 0; |
| 156 | return $stateCount; |
| 157 | } |
| 158 | /** |
| 159 | * Given a count of black/white/black/white/black pixels just seen and an end position, |
| 160 | * figures the location of the center of this run. |
| 161 | * |
| 162 | * @param int[] $stateCount |
| 163 | */ |
| 164 | private function centerFromEnd(array $stateCount, int $end) : float |
| 165 | { |
| 166 | return (float) ($end - $stateCount[4] - $stateCount[3] - $stateCount[2] / 2); |
| 167 | } |
| 168 | /** |
| 169 | * @param int[] $stateCount |
| 170 | */ |
| 171 | private function foundPatternCross(array $stateCount) : bool |
| 172 | { |
| 173 | // Allow less than 50% variance from 1-1-3-1-1 proportions |
| 174 | return $this->foundPatternVariance($stateCount, 2.0); |
| 175 | } |
| 176 | /** |
| 177 | * @param int[] $stateCount |
| 178 | */ |
| 179 | private function foundPatternDiagonal(array $stateCount) : bool |
| 180 | { |
| 181 | // Allow less than 75% variance from 1-1-3-1-1 proportions |
| 182 | return $this->foundPatternVariance($stateCount, 1.333); |
| 183 | } |
| 184 | /** |
| 185 | * @param int[] $stateCount count of black/white/black/white/black pixels just read |
| 186 | * |
| 187 | * @return bool true if the proportions of the counts is close enough to the 1/1/3/1/1 ratios |
| 188 | * used by finder patterns to be considered a match |
| 189 | */ |
| 190 | private function foundPatternVariance(array $stateCount, float $variance) : bool |
| 191 | { |
| 192 | $totalModuleSize = 0; |
| 193 | for ($i = 0; $i < 5; $i++) { |
| 194 | $count = $stateCount[$i]; |
| 195 | if ($count === 0) { |
| 196 | return \false; |
| 197 | } |
| 198 | $totalModuleSize += $count; |
| 199 | } |
| 200 | if ($totalModuleSize < 7) { |
| 201 | return \false; |
| 202 | } |
| 203 | $moduleSize = $totalModuleSize / 7.0; |
| 204 | $maxVariance = $moduleSize / $variance; |
| 205 | return abs($moduleSize - $stateCount[0]) < $maxVariance && abs($moduleSize - $stateCount[1]) < $maxVariance && abs(3.0 * $moduleSize - $stateCount[2]) < 3 * $maxVariance && abs($moduleSize - $stateCount[3]) < $maxVariance && abs($moduleSize - $stateCount[4]) < $maxVariance; |
| 206 | } |
| 207 | /** |
| 208 | * After a vertical and horizontal scan finds a potential finder pattern, this method |
| 209 | * "cross-cross-cross-checks" by scanning down diagonally through the center of the possible |
| 210 | * finder pattern to see if the same proportion is detected. |
| 211 | * |
| 212 | * @param int $centerI row where a finder pattern was detected |
| 213 | * @param int $centerJ center of the section that appears to cross a finder pattern |
| 214 | * |
| 215 | * @return bool true if proportions are withing expected limits |
| 216 | */ |
| 217 | private function crossCheckDiagonal(int $centerI, int $centerJ) : bool |
| 218 | { |
| 219 | $stateCount = $this->getCrossCheckStateCount(); |
| 220 | // Start counting up, left from center finding black center mass |
| 221 | $i = 0; |
| 222 | while ($centerI >= $i && $centerJ >= $i && $this->matrix->check($centerJ - $i, $centerI - $i)) { |
| 223 | $stateCount[2]++; |
| 224 | $i++; |
| 225 | } |
| 226 | if ($stateCount[2] === 0) { |
| 227 | return \false; |
| 228 | } |
| 229 | // Continue up, left finding white space |
| 230 | while ($centerI >= $i && $centerJ >= $i && !$this->matrix->check($centerJ - $i, $centerI - $i)) { |
| 231 | $stateCount[1]++; |
| 232 | $i++; |
| 233 | } |
| 234 | if ($stateCount[1] === 0) { |
| 235 | return \false; |
| 236 | } |
| 237 | // Continue up, left finding black border |
| 238 | while ($centerI >= $i && $centerJ >= $i && $this->matrix->check($centerJ - $i, $centerI - $i)) { |
| 239 | $stateCount[0]++; |
| 240 | $i++; |
| 241 | } |
| 242 | if ($stateCount[0] === 0) { |
| 243 | return \false; |
| 244 | } |
| 245 | $dimension = $this->matrix->getSize(); |
| 246 | // Now also count down, right from center |
| 247 | $i = 1; |
| 248 | // phpcs:ignore |
| 249 | while ($centerI + $i < $dimension && $centerJ + $i < $dimension && $this->matrix->check($centerJ + $i, $centerI + $i)) { |
| 250 | $stateCount[2]++; |
| 251 | $i++; |
| 252 | } |
| 253 | // phpcs:ignore |
| 254 | while ($centerI + $i < $dimension && $centerJ + $i < $dimension && !$this->matrix->check($centerJ + $i, $centerI + $i)) { |
| 255 | $stateCount[3]++; |
| 256 | $i++; |
| 257 | } |
| 258 | if ($stateCount[3] === 0) { |
| 259 | return \false; |
| 260 | } |
| 261 | // phpcs:ignore |
| 262 | while ($centerI + $i < $dimension && $centerJ + $i < $dimension && $this->matrix->check($centerJ + $i, $centerI + $i)) { |
| 263 | $stateCount[4]++; |
| 264 | $i++; |
| 265 | } |
| 266 | if ($stateCount[4] === 0) { |
| 267 | return \false; |
| 268 | } |
| 269 | return $this->foundPatternDiagonal($stateCount); |
| 270 | } |
| 271 | /** |
| 272 | * After a horizontal scan finds a potential finder pattern, this method |
| 273 | * "cross-checks" by scanning down vertically through the center of the possible |
| 274 | * finder pattern to see if the same proportion is detected. |
| 275 | * |
| 276 | * @param int $startI row where a finder pattern was detected |
| 277 | * @param int $centerJ center of the section that appears to cross a finder pattern |
| 278 | * @param int $maxCount maximum reasonable number of modules that should be |
| 279 | * observed in any reading state, based on the results of the horizontal scan |
| 280 | * @param int $originalStateCountTotal |
| 281 | * |
| 282 | * @return float|null vertical center of finder pattern, or null if not found |
| 283 | * @noinspection DuplicatedCode |
| 284 | */ |
| 285 | private function crossCheckVertical(int $startI, int $centerJ, int $maxCount, int $originalStateCountTotal) : ?float |
| 286 | { |
| 287 | $maxI = $this->matrix->getSize(); |
| 288 | $stateCount = $this->getCrossCheckStateCount(); |
| 289 | // Start counting up from center |
| 290 | $i = $startI; |
| 291 | while ($i >= 0 && $this->matrix->check($centerJ, $i)) { |
| 292 | $stateCount[2]++; |
| 293 | $i--; |
| 294 | } |
| 295 | if ($i < 0) { |
| 296 | return null; |
| 297 | } |
| 298 | while ($i >= 0 && !$this->matrix->check($centerJ, $i) && $stateCount[1] <= $maxCount) { |
| 299 | $stateCount[1]++; |
| 300 | $i--; |
| 301 | } |
| 302 | // If already too many modules in this state or ran off the edge: |
| 303 | if ($i < 0 || $stateCount[1] > $maxCount) { |
| 304 | return null; |
| 305 | } |
| 306 | while ($i >= 0 && $this->matrix->check($centerJ, $i) && $stateCount[0] <= $maxCount) { |
| 307 | $stateCount[0]++; |
| 308 | $i--; |
| 309 | } |
| 310 | if ($stateCount[0] > $maxCount) { |
| 311 | return null; |
| 312 | } |
| 313 | // Now also count down from center |
| 314 | $i = $startI + 1; |
| 315 | while ($i < $maxI && $this->matrix->check($centerJ, $i)) { |
| 316 | $stateCount[2]++; |
| 317 | $i++; |
| 318 | } |
| 319 | if ($i === $maxI) { |
| 320 | return null; |
| 321 | } |
| 322 | while ($i < $maxI && !$this->matrix->check($centerJ, $i) && $stateCount[3] < $maxCount) { |
| 323 | $stateCount[3]++; |
| 324 | $i++; |
| 325 | } |
| 326 | if ($i === $maxI || $stateCount[3] >= $maxCount) { |
| 327 | return null; |
| 328 | } |
| 329 | while ($i < $maxI && $this->matrix->check($centerJ, $i) && $stateCount[4] < $maxCount) { |
| 330 | $stateCount[4]++; |
| 331 | $i++; |
| 332 | } |
| 333 | if ($stateCount[4] >= $maxCount) { |
| 334 | return null; |
| 335 | } |
| 336 | // If we found a finder-pattern-like section, but its size is more than 40% different from |
| 337 | // the original, assume it's a false positive |
| 338 | $stateCountTotal = $stateCount[0] + $stateCount[1] + $stateCount[2] + $stateCount[3] + $stateCount[4]; |
| 339 | if (5 * abs($stateCountTotal - $originalStateCountTotal) >= 2 * $originalStateCountTotal) { |
| 340 | return null; |
| 341 | } |
| 342 | if (!$this->foundPatternCross($stateCount)) { |
| 343 | return null; |
| 344 | } |
| 345 | return $this->centerFromEnd($stateCount, $i); |
| 346 | } |
| 347 | /** |
| 348 | * Like #crossCheckVertical(int, int, int, int), and in fact is basically identical, |
| 349 | * except it reads horizontally instead of vertically. This is used to cross-cross |
| 350 | * check a vertical cross-check and locate the real center of the alignment pattern. |
| 351 | * @noinspection DuplicatedCode |
| 352 | */ |
| 353 | private function crossCheckHorizontal(int $startJ, int $centerI, int $maxCount, int $originalStateCountTotal) : ?float |
| 354 | { |
| 355 | $maxJ = $this->matrix->getSize(); |
| 356 | $stateCount = $this->getCrossCheckStateCount(); |
| 357 | $j = $startJ; |
| 358 | while ($j >= 0 && $this->matrix->check($j, $centerI)) { |
| 359 | $stateCount[2]++; |
| 360 | $j--; |
| 361 | } |
| 362 | if ($j < 0) { |
| 363 | return null; |
| 364 | } |
| 365 | while ($j >= 0 && !$this->matrix->check($j, $centerI) && $stateCount[1] <= $maxCount) { |
| 366 | $stateCount[1]++; |
| 367 | $j--; |
| 368 | } |
| 369 | if ($j < 0 || $stateCount[1] > $maxCount) { |
| 370 | return null; |
| 371 | } |
| 372 | while ($j >= 0 && $this->matrix->check($j, $centerI) && $stateCount[0] <= $maxCount) { |
| 373 | $stateCount[0]++; |
| 374 | $j--; |
| 375 | } |
| 376 | if ($stateCount[0] > $maxCount) { |
| 377 | return null; |
| 378 | } |
| 379 | $j = $startJ + 1; |
| 380 | while ($j < $maxJ && $this->matrix->check($j, $centerI)) { |
| 381 | $stateCount[2]++; |
| 382 | $j++; |
| 383 | } |
| 384 | if ($j === $maxJ) { |
| 385 | return null; |
| 386 | } |
| 387 | while ($j < $maxJ && !$this->matrix->check($j, $centerI) && $stateCount[3] < $maxCount) { |
| 388 | $stateCount[3]++; |
| 389 | $j++; |
| 390 | } |
| 391 | if ($j === $maxJ || $stateCount[3] >= $maxCount) { |
| 392 | return null; |
| 393 | } |
| 394 | while ($j < $maxJ && $this->matrix->check($j, $centerI) && $stateCount[4] < $maxCount) { |
| 395 | $stateCount[4]++; |
| 396 | $j++; |
| 397 | } |
| 398 | if ($stateCount[4] >= $maxCount) { |
| 399 | return null; |
| 400 | } |
| 401 | // If we found a finder-pattern-like section, but its size is significantly different from |
| 402 | // the original, assume it's a false positive |
| 403 | $stateCountTotal = $stateCount[0] + $stateCount[1] + $stateCount[2] + $stateCount[3] + $stateCount[4]; |
| 404 | if (5 * abs($stateCountTotal - $originalStateCountTotal) >= $originalStateCountTotal) { |
| 405 | return null; |
| 406 | } |
| 407 | if (!$this->foundPatternCross($stateCount)) { |
| 408 | return null; |
| 409 | } |
| 410 | return $this->centerFromEnd($stateCount, $j); |
| 411 | } |
| 412 | /** |
| 413 | * This is called when a horizontal scan finds a possible alignment pattern. It will |
| 414 | * cross-check with a vertical scan, and if successful, will, ah, cross-cross-check |
| 415 | * with another horizontal scan. This is needed primarily to locate the real horizontal |
| 416 | * center of the pattern in cases of extreme skew. |
| 417 | * And then we cross-cross-cross check with another diagonal scan. |
| 418 | * |
| 419 | * If that succeeds the finder pattern location is added to a list that tracks |
| 420 | * the number of times each location has been nearly-matched as a finder pattern. |
| 421 | * Each additional find is more evidence that the location is in fact a finder |
| 422 | * pattern center |
| 423 | * |
| 424 | * @param int[] $stateCount reading state module counts from horizontal scan |
| 425 | * @param int $i row where finder pattern may be found |
| 426 | * @param int $j end of possible finder pattern in row |
| 427 | * |
| 428 | * @return bool if a finder pattern candidate was found this time |
| 429 | */ |
| 430 | private function handlePossibleCenter(array $stateCount, int $i, int $j) : bool |
| 431 | { |
| 432 | $stateCountTotal = $stateCount[0] + $stateCount[1] + $stateCount[2] + $stateCount[3] + $stateCount[4]; |
| 433 | $centerJ = $this->centerFromEnd($stateCount, $j); |
| 434 | $centerI = $this->crossCheckVertical($i, (int) $centerJ, $stateCount[2], $stateCountTotal); |
| 435 | if ($centerI !== null) { |
| 436 | // Re-cross check |
| 437 | $centerJ = $this->crossCheckHorizontal((int) $centerJ, (int) $centerI, $stateCount[2], $stateCountTotal); |
| 438 | if ($centerJ !== null && $this->crossCheckDiagonal((int) $centerI, (int) $centerJ)) { |
| 439 | $estimatedModuleSize = $stateCountTotal / 7.0; |
| 440 | $found = \false; |
| 441 | // cautious (was in for fool in which $this->possibleCenters is updated) |
| 442 | $count = count($this->possibleCenters); |
| 443 | for ($index = 0; $index < $count; $index++) { |
| 444 | $center = $this->possibleCenters[$index]; |
| 445 | // Look for about the same center and module size: |
| 446 | if ($center->aboutEquals($estimatedModuleSize, $centerI, $centerJ)) { |
| 447 | $this->possibleCenters[$index] = $center->combineEstimate($centerI, $centerJ, $estimatedModuleSize); |
| 448 | $found = \true; |
| 449 | break; |
| 450 | } |
| 451 | } |
| 452 | if (!$found) { |
| 453 | $point = new FinderPattern($centerJ, $centerI, $estimatedModuleSize); |
| 454 | $this->possibleCenters[] = $point; |
| 455 | } |
| 456 | return \true; |
| 457 | } |
| 458 | } |
| 459 | return \false; |
| 460 | } |
| 461 | /** |
| 462 | * @return int number of rows we could safely skip during scanning, based on the first |
| 463 | * two finder patterns that have been located. In some cases their position will |
| 464 | * allow us to infer that the third pattern must lie below a certain point farther |
| 465 | * down in the image. |
| 466 | */ |
| 467 | private function findRowSkip() : int |
| 468 | { |
| 469 | $max = count($this->possibleCenters); |
| 470 | if ($max <= 1) { |
| 471 | return 0; |
| 472 | } |
| 473 | $firstConfirmedCenter = null; |
| 474 | foreach ($this->possibleCenters as $center) { |
| 475 | if ($center->getCount() >= self::CENTER_QUORUM) { |
| 476 | if ($firstConfirmedCenter === null) { |
| 477 | $firstConfirmedCenter = $center; |
| 478 | } else { |
| 479 | // We have two confirmed centers |
| 480 | // How far down can we skip before resuming looking for the next |
| 481 | // pattern? In the worst case, only the difference between the |
| 482 | // difference in the x / y coordinates of the two centers. |
| 483 | // This is the case where you find top left last. |
| 484 | $this->hasSkipped = \true; |
| 485 | return (int) ((abs($firstConfirmedCenter->getX() - $center->getX()) - abs($firstConfirmedCenter->getY() - $center->getY())) / 2); |
| 486 | } |
| 487 | } |
| 488 | } |
| 489 | return 0; |
| 490 | } |
| 491 | /** |
| 492 | * @return bool true if we have found at least 3 finder patterns that have been detected |
| 493 | * at least #CENTER_QUORUM times each, and, the estimated module size of the |
| 494 | * candidates is "pretty similar" |
| 495 | */ |
| 496 | private function haveMultiplyConfirmedCenters() : bool |
| 497 | { |
| 498 | $confirmedCount = 0; |
| 499 | $totalModuleSize = 0.0; |
| 500 | $max = count($this->possibleCenters); |
| 501 | foreach ($this->possibleCenters as $pattern) { |
| 502 | if ($pattern->getCount() >= self::CENTER_QUORUM) { |
| 503 | $confirmedCount++; |
| 504 | $totalModuleSize += $pattern->getEstimatedModuleSize(); |
| 505 | } |
| 506 | } |
| 507 | if ($confirmedCount < 3) { |
| 508 | return \false; |
| 509 | } |
| 510 | // OK, we have at least 3 confirmed centers, but, it's possible that one is a "false positive" |
| 511 | // and that we need to keep looking. We detect this by asking if the estimated module sizes |
| 512 | // vary too much. We arbitrarily say that when the total deviation from average exceeds |
| 513 | // 5% of the total module size estimates, it's too much. |
| 514 | $average = $totalModuleSize / (float) $max; |
| 515 | $totalDeviation = 0.0; |
| 516 | foreach ($this->possibleCenters as $pattern) { |
| 517 | $totalDeviation += abs($pattern->getEstimatedModuleSize() - $average); |
| 518 | } |
| 519 | return $totalDeviation <= 0.05 * $totalModuleSize; |
| 520 | } |
| 521 | /** |
| 522 | * @return \chillerlan\QRCode\Detector\FinderPattern[] the 3 best FinderPatterns from our list of candidates. The "best" are |
| 523 | * those that have been detected at least #CENTER_QUORUM times, and whose module |
| 524 | * size differs from the average among those patterns the least |
| 525 | * @throws \chillerlan\QRCode\Detector\QRCodeDetectorException if 3 such finder patterns do not exist |
| 526 | */ |
| 527 | private function selectBestPatterns() : array |
| 528 | { |
| 529 | $startSize = count($this->possibleCenters); |
| 530 | if ($startSize < 3) { |
| 531 | throw new QRCodeDetectorException('could not find enough finder patterns'); |
| 532 | } |
| 533 | usort($this->possibleCenters, fn(FinderPattern $a, FinderPattern $b) => $a->getEstimatedModuleSize() <=> $b->getEstimatedModuleSize()); |
| 534 | $distortion = PHP_FLOAT_MAX; |
| 535 | $bestPatterns = []; |
| 536 | for ($i = 0; $i < $startSize - 2; $i++) { |
| 537 | $fpi = $this->possibleCenters[$i]; |
| 538 | $minModuleSize = $fpi->getEstimatedModuleSize(); |
| 539 | for ($j = $i + 1; $j < $startSize - 1; $j++) { |
| 540 | $fpj = $this->possibleCenters[$j]; |
| 541 | $squares0 = $fpi->getSquaredDistance($fpj); |
| 542 | for ($k = $j + 1; $k < $startSize; $k++) { |
| 543 | $fpk = $this->possibleCenters[$k]; |
| 544 | $maxModuleSize = $fpk->getEstimatedModuleSize(); |
| 545 | // module size is not similar |
| 546 | if ($maxModuleSize > $minModuleSize * 1.4) { |
| 547 | continue; |
| 548 | } |
| 549 | $a = $squares0; |
| 550 | $b = $fpj->getSquaredDistance($fpk); |
| 551 | $c = $fpi->getSquaredDistance($fpk); |
| 552 | // sorts ascending - inlined |
| 553 | if ($a < $b) { |
| 554 | if ($b > $c) { |
| 555 | if ($a < $c) { |
| 556 | $temp = $b; |
| 557 | $b = $c; |
| 558 | $c = $temp; |
| 559 | } else { |
| 560 | $temp = $a; |
| 561 | $a = $c; |
| 562 | $c = $b; |
| 563 | $b = $temp; |
| 564 | } |
| 565 | } |
| 566 | } else { |
| 567 | if ($b < $c) { |
| 568 | if ($a < $c) { |
| 569 | $temp = $a; |
| 570 | $a = $b; |
| 571 | $b = $temp; |
| 572 | } else { |
| 573 | $temp = $a; |
| 574 | $a = $b; |
| 575 | $b = $c; |
| 576 | $c = $temp; |
| 577 | } |
| 578 | } else { |
| 579 | $temp = $a; |
| 580 | $a = $c; |
| 581 | $c = $temp; |
| 582 | } |
| 583 | } |
| 584 | // a^2 + b^2 = c^2 (Pythagorean theorem), and a = b (isosceles triangle). |
| 585 | // Since any right triangle satisfies the formula c^2 - b^2 - a^2 = 0, |
| 586 | // we need to check both two equal sides separately. |
| 587 | // The value of |c^2 - 2 * b^2| + |c^2 - 2 * a^2| increases as dissimilarity |
| 588 | // from isosceles right triangle. |
| 589 | $d = abs($c - 2 * $b) + abs($c - 2 * $a); |
| 590 | if ($d < $distortion) { |
| 591 | $distortion = $d; |
| 592 | $bestPatterns = [$fpi, $fpj, $fpk]; |
| 593 | } |
| 594 | } |
| 595 | } |
| 596 | } |
| 597 | if ($distortion === PHP_FLOAT_MAX) { |
| 598 | throw new QRCodeDetectorException('finder patterns may be too distorted'); |
| 599 | } |
| 600 | return $bestPatterns; |
| 601 | } |
| 602 | /** |
| 603 | * Orders an array of three ResultPoints in an order [A,B,C] such that AB is less than AC |
| 604 | * and BC is less than AC, and the angle between BC and BA is less than 180 degrees. |
| 605 | * |
| 606 | * @param \chillerlan\QRCode\Detector\FinderPattern[] $patterns array of three FinderPattern to order |
| 607 | * |
| 608 | * @return \chillerlan\QRCode\Detector\FinderPattern[] |
| 609 | */ |
| 610 | private function orderBestPatterns(array $patterns) : array |
| 611 | { |
| 612 | // Find distances between pattern centers |
| 613 | $zeroOneDistance = $patterns[0]->getDistance($patterns[1]); |
| 614 | $oneTwoDistance = $patterns[1]->getDistance($patterns[2]); |
| 615 | $zeroTwoDistance = $patterns[0]->getDistance($patterns[2]); |
| 616 | // Assume one closest to other two is B; A and C will just be guesses at first |
| 617 | if ($oneTwoDistance >= $zeroOneDistance && $oneTwoDistance >= $zeroTwoDistance) { |
| 618 | [$pointB, $pointA, $pointC] = $patterns; |
| 619 | } elseif ($zeroTwoDistance >= $oneTwoDistance && $zeroTwoDistance >= $zeroOneDistance) { |
| 620 | [$pointA, $pointB, $pointC] = $patterns; |
| 621 | } else { |
| 622 | [$pointA, $pointC, $pointB] = $patterns; |
| 623 | } |
| 624 | // Use cross product to figure out whether A and C are correct or flipped. |
| 625 | // This asks whether BC x BA has a positive z component, which is the arrangement |
| 626 | // we want for A, B, C. If it's negative, then we've got it flipped around and |
| 627 | // should swap A and C. |
| 628 | if ($this->crossProductZ($pointA, $pointB, $pointC) < 0.0) { |
| 629 | $temp = $pointA; |
| 630 | $pointA = $pointC; |
| 631 | $pointC = $temp; |
| 632 | } |
| 633 | return [$pointA, $pointB, $pointC]; |
| 634 | } |
| 635 | /** |
| 636 | * Returns the z component of the cross product between vectors BC and BA. |
| 637 | */ |
| 638 | private function crossProductZ(FinderPattern $pointA, FinderPattern $pointB, FinderPattern $pointC) : float |
| 639 | { |
| 640 | $bX = $pointB->getX(); |
| 641 | $bY = $pointB->getY(); |
| 642 | return ($pointC->getX() - $bX) * ($pointA->getY() - $bY) - ($pointC->getY() - $bY) * ($pointA->getX() - $bX); |
| 643 | } |
| 644 | } |
| 645 |