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Diffstat (limited to 'vendor/chillerlan/php-qrcode/src/Detector/FinderPatternFinder.php')
-rw-r--r-- | vendor/chillerlan/php-qrcode/src/Detector/FinderPatternFinder.php | 773 |
1 files changed, 773 insertions, 0 deletions
diff --git a/vendor/chillerlan/php-qrcode/src/Detector/FinderPatternFinder.php b/vendor/chillerlan/php-qrcode/src/Detector/FinderPatternFinder.php new file mode 100644 index 000000000..61628d063 --- /dev/null +++ b/vendor/chillerlan/php-qrcode/src/Detector/FinderPatternFinder.php @@ -0,0 +1,773 @@ +<?php +/** + * Class FinderPatternFinder + * + * @created 17.01.2021 + * @author ZXing Authors + * @author Smiley <smiley@chillerlan.net> + * @copyright 2021 Smiley + * @license Apache-2.0 + * + * @phan-file-suppress PhanTypePossiblyInvalidDimOffset + */ + +namespace chillerlan\QRCode\Detector; + +use chillerlan\QRCode\Decoder\BitMatrix; +use function abs, count, intdiv, usort; +use const PHP_FLOAT_MAX; + +/** + * This class attempts to find finder patterns in a QR Code. Finder patterns are the square + * markers at three corners of a QR Code. + * + * This class is thread-safe but not reentrant. Each thread must allocate its own object. + * + * @author Sean Owen + */ +final class FinderPatternFinder{ + + private const MIN_SKIP = 2; + private const MAX_MODULES = 177; // 1 pixel/module times 3 modules/center + private const CENTER_QUORUM = 2; // support up to version 10 for mobile clients + private BitMatrix $matrix; + /** @var \chillerlan\QRCode\Detector\FinderPattern[] */ + private array $possibleCenters; + private bool $hasSkipped = false; + + /** + * Creates a finder that will search the image for three finder patterns. + * + * @param BitMatrix $matrix image to search + */ + public function __construct(BitMatrix $matrix){ + $this->matrix = $matrix; + $this->possibleCenters = []; + } + + /** + * @return \chillerlan\QRCode\Detector\FinderPattern[] + */ + public function find():array{ + $dimension = $this->matrix->getSize(); + + // We are looking for black/white/black/white/black modules in + // 1:1:3:1:1 ratio; this tracks the number of such modules seen so far + // Let's assume that the maximum version QR Code we support takes up 1/4 the height of the + // image, and then account for the center being 3 modules in size. This gives the smallest + // number of pixels the center could be, so skip this often. + $iSkip = intdiv((3 * $dimension), (4 * self::MAX_MODULES)); + + if($iSkip < self::MIN_SKIP){ + $iSkip = self::MIN_SKIP; + } + + $done = false; + + for($i = ($iSkip - 1); ($i < $dimension) && !$done; $i += $iSkip){ + // Get a row of black/white values + $stateCount = $this->getCrossCheckStateCount(); + $currentState = 0; + + for($j = 0; $j < $dimension; $j++){ + + // Black pixel + if($this->matrix->check($j, $i)){ + // Counting white pixels + if(($currentState & 1) === 1){ + $currentState++; + } + + $stateCount[$currentState]++; + } + // White pixel + else{ + // Counting black pixels + if(($currentState & 1) === 0){ + // A winner? + if($currentState === 4){ + // Yes + if($this->foundPatternCross($stateCount)){ + $confirmed = $this->handlePossibleCenter($stateCount, $i, $j); + + if($confirmed){ + // Start examining every other line. Checking each line turned out to be too + // expensive and didn't improve performance. + $iSkip = 3; + + if($this->hasSkipped){ + $done = $this->haveMultiplyConfirmedCenters(); + } + else{ + $rowSkip = $this->findRowSkip(); + + if($rowSkip > $stateCount[2]){ + // Skip rows between row of lower confirmed center + // and top of presumed third confirmed center + // but back up a bit to get a full chance of detecting + // it, entire width of center of finder pattern + + // Skip by rowSkip, but back off by $stateCount[2] (size of last center + // of pattern we saw) to be conservative, and also back off by iSkip which + // is about to be re-added + $i += ($rowSkip - $stateCount[2] - $iSkip); + $j = ($dimension - 1); + } + } + } + else{ + $stateCount = $this->doShiftCounts2($stateCount); + $currentState = 3; + + continue; + } + // Clear state to start looking again + $currentState = 0; + $stateCount = $this->getCrossCheckStateCount(); + } + // No, shift counts back by two + else{ + $stateCount = $this->doShiftCounts2($stateCount); + $currentState = 3; + } + } + else{ + $stateCount[++$currentState]++; + } + } + // Counting white pixels + else{ + $stateCount[$currentState]++; + } + } + } + + if($this->foundPatternCross($stateCount)){ + $confirmed = $this->handlePossibleCenter($stateCount, $i, $dimension); + + if($confirmed){ + $iSkip = $stateCount[0]; + + if($this->hasSkipped){ + // Found a third one + $done = $this->haveMultiplyConfirmedCenters(); + } + } + } + } + + return $this->orderBestPatterns($this->selectBestPatterns()); + } + + /** + * @return int[] + */ + private function getCrossCheckStateCount():array{ + return [0, 0, 0, 0, 0]; + } + + /** + * @param int[] $stateCount + * + * @return int[] + */ + private function doShiftCounts2(array $stateCount):array{ + $stateCount[0] = $stateCount[2]; + $stateCount[1] = $stateCount[3]; + $stateCount[2] = $stateCount[4]; + $stateCount[3] = 1; + $stateCount[4] = 0; + + return $stateCount; + } + + /** + * Given a count of black/white/black/white/black pixels just seen and an end position, + * figures the location of the center of this run. + * + * @param int[] $stateCount + */ + private function centerFromEnd(array $stateCount, int $end):float{ + return (float)(($end - $stateCount[4] - $stateCount[3]) - $stateCount[2] / 2); + } + + /** + * @param int[] $stateCount + */ + private function foundPatternCross(array $stateCount):bool{ + // Allow less than 50% variance from 1-1-3-1-1 proportions + return $this->foundPatternVariance($stateCount, 2.0); + } + + /** + * @param int[] $stateCount + */ + private function foundPatternDiagonal(array $stateCount):bool{ + // Allow less than 75% variance from 1-1-3-1-1 proportions + return $this->foundPatternVariance($stateCount, 1.333); + } + + /** + * @param int[] $stateCount count of black/white/black/white/black pixels just read + * + * @return bool true if the proportions of the counts is close enough to the 1/1/3/1/1 ratios + * used by finder patterns to be considered a match + */ + private function foundPatternVariance(array $stateCount, float $variance):bool{ + $totalModuleSize = 0; + + for($i = 0; $i < 5; $i++){ + $count = $stateCount[$i]; + + if($count === 0){ + return false; + } + + $totalModuleSize += $count; + } + + if($totalModuleSize < 7){ + return false; + } + + $moduleSize = ($totalModuleSize / 7.0); + $maxVariance = ($moduleSize / $variance); + + return + abs($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; + } + + /** + * After a vertical and horizontal scan finds a potential finder pattern, this method + * "cross-cross-cross-checks" by scanning down diagonally through the center of the possible + * finder pattern to see if the same proportion is detected. + * + * @param int $centerI row where a finder pattern was detected + * @param int $centerJ center of the section that appears to cross a finder pattern + * + * @return bool true if proportions are withing expected limits + */ + private function crossCheckDiagonal(int $centerI, int $centerJ):bool{ + $stateCount = $this->getCrossCheckStateCount(); + + // Start counting up, left from center finding black center mass + $i = 0; + + while($centerI >= $i && $centerJ >= $i && $this->matrix->check(($centerJ - $i), ($centerI - $i))){ + $stateCount[2]++; + $i++; + } + + if($stateCount[2] === 0){ + return false; + } + + // Continue up, left finding white space + while($centerI >= $i && $centerJ >= $i && !$this->matrix->check(($centerJ - $i), ($centerI - $i))){ + $stateCount[1]++; + $i++; + } + + if($stateCount[1] === 0){ + return false; + } + + // Continue up, left finding black border + while($centerI >= $i && $centerJ >= $i && $this->matrix->check(($centerJ - $i), ($centerI - $i))){ + $stateCount[0]++; + $i++; + } + + if($stateCount[0] === 0){ + return false; + } + + $dimension = $this->matrix->getSize(); + + // Now also count down, right from center + $i = 1; + // phpcs:ignore + while(($centerI + $i) < $dimension && ($centerJ + $i) < $dimension && $this->matrix->check(($centerJ + $i), ($centerI + $i))){ + $stateCount[2]++; + $i++; + } + + // phpcs:ignore + while(($centerI + $i) < $dimension && ($centerJ + $i) < $dimension && !$this->matrix->check(($centerJ + $i), ($centerI + $i))){ + $stateCount[3]++; + $i++; + } + + if($stateCount[3] === 0){ + return false; + } + + // phpcs:ignore + while(($centerI + $i) < $dimension && ($centerJ + $i) < $dimension && $this->matrix->check(($centerJ + $i), ($centerI + $i))){ + $stateCount[4]++; + $i++; + } + + if($stateCount[4] === 0){ + return false; + } + + return $this->foundPatternDiagonal($stateCount); + } + + /** + * After a horizontal scan finds a potential finder pattern, this method + * "cross-checks" by scanning down vertically through the center of the possible + * finder pattern to see if the same proportion is detected. + * + * @param int $startI row where a finder pattern was detected + * @param int $centerJ center of the section that appears to cross a finder pattern + * @param int $maxCount maximum reasonable number of modules that should be + * observed in any reading state, based on the results of the horizontal scan + * @param int $originalStateCountTotal + * + * @return float|null vertical center of finder pattern, or null if not found + * @noinspection DuplicatedCode + */ + private function crossCheckVertical(int $startI, int $centerJ, int $maxCount, int $originalStateCountTotal):?float{ + $maxI = $this->matrix->getSize(); + $stateCount = $this->getCrossCheckStateCount(); + + // Start counting up from center + $i = $startI; + while($i >= 0 && $this->matrix->check($centerJ, $i)){ + $stateCount[2]++; + $i--; + } + + if($i < 0){ + return null; + } + + while($i >= 0 && !$this->matrix->check($centerJ, $i) && $stateCount[1] <= $maxCount){ + $stateCount[1]++; + $i--; + } + + // If already too many modules in this state or ran off the edge: + if($i < 0 || $stateCount[1] > $maxCount){ + return null; + } + + while($i >= 0 && $this->matrix->check($centerJ, $i) && $stateCount[0] <= $maxCount){ + $stateCount[0]++; + $i--; + } + + if($stateCount[0] > $maxCount){ + return null; + } + + // Now also count down from center + $i = ($startI + 1); + while($i < $maxI && $this->matrix->check($centerJ, $i)){ + $stateCount[2]++; + $i++; + } + + if($i === $maxI){ + return null; + } + + while($i < $maxI && !$this->matrix->check($centerJ, $i) && $stateCount[3] < $maxCount){ + $stateCount[3]++; + $i++; + } + + if($i === $maxI || $stateCount[3] >= $maxCount){ + return null; + } + + while($i < $maxI && $this->matrix->check($centerJ, $i) && $stateCount[4] < $maxCount){ + $stateCount[4]++; + $i++; + } + + if($stateCount[4] >= $maxCount){ + return null; + } + + // If we found a finder-pattern-like section, but its size is more than 40% different from + // the original, assume it's a false positive + $stateCountTotal = ($stateCount[0] + $stateCount[1] + $stateCount[2] + $stateCount[3] + $stateCount[4]); + + if((5 * abs($stateCountTotal - $originalStateCountTotal)) >= (2 * $originalStateCountTotal)){ + return null; + } + + if(!$this->foundPatternCross($stateCount)){ + return null; + } + + return $this->centerFromEnd($stateCount, $i); + } + + /** + * Like #crossCheckVertical(int, int, int, int), and in fact is basically identical, + * except it reads horizontally instead of vertically. This is used to cross-cross + * check a vertical cross-check and locate the real center of the alignment pattern. + * @noinspection DuplicatedCode + */ + private function crossCheckHorizontal(int $startJ, int $centerI, int $maxCount, int $originalStateCountTotal):?float{ + $maxJ = $this->matrix->getSize(); + $stateCount = $this->getCrossCheckStateCount(); + + $j = $startJ; + while($j >= 0 && $this->matrix->check($j, $centerI)){ + $stateCount[2]++; + $j--; + } + + if($j < 0){ + return null; + } + + while($j >= 0 && !$this->matrix->check($j, $centerI) && $stateCount[1] <= $maxCount){ + $stateCount[1]++; + $j--; + } + + if($j < 0 || $stateCount[1] > $maxCount){ + return null; + } + + while($j >= 0 && $this->matrix->check($j, $centerI) && $stateCount[0] <= $maxCount){ + $stateCount[0]++; + $j--; + } + + if($stateCount[0] > $maxCount){ + return null; + } + + $j = ($startJ + 1); + while($j < $maxJ && $this->matrix->check($j, $centerI)){ + $stateCount[2]++; + $j++; + } + + if($j === $maxJ){ + return null; + } + + while($j < $maxJ && !$this->matrix->check($j, $centerI) && $stateCount[3] < $maxCount){ + $stateCount[3]++; + $j++; + } + + if($j === $maxJ || $stateCount[3] >= $maxCount){ + return null; + } + + while($j < $maxJ && $this->matrix->check($j, $centerI) && $stateCount[4] < $maxCount){ + $stateCount[4]++; + $j++; + } + + if($stateCount[4] >= $maxCount){ + return null; + } + + // If we found a finder-pattern-like section, but its size is significantly different from + // the original, assume it's a false positive + $stateCountTotal = ($stateCount[0] + $stateCount[1] + $stateCount[2] + $stateCount[3] + $stateCount[4]); + + if((5 * abs($stateCountTotal - $originalStateCountTotal)) >= $originalStateCountTotal){ + return null; + } + + if(!$this->foundPatternCross($stateCount)){ + return null; + } + + return $this->centerFromEnd($stateCount, $j); + } + + /** + * This is called when a horizontal scan finds a possible alignment pattern. It will + * cross-check with a vertical scan, and if successful, will, ah, cross-cross-check + * with another horizontal scan. This is needed primarily to locate the real horizontal + * center of the pattern in cases of extreme skew. + * And then we cross-cross-cross check with another diagonal scan. + * + * If that succeeds the finder pattern location is added to a list that tracks + * the number of times each location has been nearly-matched as a finder pattern. + * Each additional find is more evidence that the location is in fact a finder + * pattern center + * + * @param int[] $stateCount reading state module counts from horizontal scan + * @param int $i row where finder pattern may be found + * @param int $j end of possible finder pattern in row + * + * @return bool if a finder pattern candidate was found this time + */ + private function handlePossibleCenter(array $stateCount, int $i, int $j):bool{ + $stateCountTotal = ($stateCount[0] + $stateCount[1] + $stateCount[2] + $stateCount[3] + $stateCount[4]); + $centerJ = $this->centerFromEnd($stateCount, $j); + $centerI = $this->crossCheckVertical($i, (int)$centerJ, $stateCount[2], $stateCountTotal); + + if($centerI !== null){ + // Re-cross check + $centerJ = $this->crossCheckHorizontal((int)$centerJ, (int)$centerI, $stateCount[2], $stateCountTotal); + if($centerJ !== null && ($this->crossCheckDiagonal((int)$centerI, (int)$centerJ))){ + $estimatedModuleSize = ($stateCountTotal / 7.0); + $found = false; + + // cautious (was in for fool in which $this->possibleCenters is updated) + $count = count($this->possibleCenters); + + for($index = 0; $index < $count; $index++){ + $center = $this->possibleCenters[$index]; + // Look for about the same center and module size: + if($center->aboutEquals($estimatedModuleSize, $centerI, $centerJ)){ + $this->possibleCenters[$index] = $center->combineEstimate($centerI, $centerJ, $estimatedModuleSize); + $found = true; + break; + } + } + + if(!$found){ + $point = new FinderPattern($centerJ, $centerI, $estimatedModuleSize); + $this->possibleCenters[] = $point; + } + + return true; + } + } + + return false; + } + + /** + * @return int number of rows we could safely skip during scanning, based on the first + * two finder patterns that have been located. In some cases their position will + * allow us to infer that the third pattern must lie below a certain point farther + * down in the image. + */ + private function findRowSkip():int{ + $max = count($this->possibleCenters); + + if($max <= 1){ + return 0; + } + + $firstConfirmedCenter = null; + + foreach($this->possibleCenters as $center){ + + if($center->getCount() >= self::CENTER_QUORUM){ + + if($firstConfirmedCenter === null){ + $firstConfirmedCenter = $center; + } + else{ + // We have two confirmed centers + // How far down can we skip before resuming looking for the next + // pattern? In the worst case, only the difference between the + // difference in the x / y coordinates of the two centers. + // This is the case where you find top left last. + $this->hasSkipped = true; + + return (int)((abs($firstConfirmedCenter->getX() - $center->getX()) - + abs($firstConfirmedCenter->getY() - $center->getY())) / 2); + } + } + } + + return 0; + } + + /** + * @return bool true if we have found at least 3 finder patterns that have been detected + * at least #CENTER_QUORUM times each, and, the estimated module size of the + * candidates is "pretty similar" + */ + private function haveMultiplyConfirmedCenters():bool{ + $confirmedCount = 0; + $totalModuleSize = 0.0; + $max = count($this->possibleCenters); + + foreach($this->possibleCenters as $pattern){ + if($pattern->getCount() >= self::CENTER_QUORUM){ + $confirmedCount++; + $totalModuleSize += $pattern->getEstimatedModuleSize(); + } + } + + if($confirmedCount < 3){ + return false; + } + // OK, we have at least 3 confirmed centers, but, it's possible that one is a "false positive" + // and that we need to keep looking. We detect this by asking if the estimated module sizes + // vary too much. We arbitrarily say that when the total deviation from average exceeds + // 5% of the total module size estimates, it's too much. + $average = ($totalModuleSize / (float)$max); + $totalDeviation = 0.0; + + foreach($this->possibleCenters as $pattern){ + $totalDeviation += abs($pattern->getEstimatedModuleSize() - $average); + } + + return $totalDeviation <= (0.05 * $totalModuleSize); + } + + /** + * @return \chillerlan\QRCode\Detector\FinderPattern[] the 3 best FinderPatterns from our list of candidates. The "best" are + * those that have been detected at least #CENTER_QUORUM times, and whose module + * size differs from the average among those patterns the least + * @throws \chillerlan\QRCode\Detector\QRCodeDetectorException if 3 such finder patterns do not exist + */ + private function selectBestPatterns():array{ + $startSize = count($this->possibleCenters); + + if($startSize < 3){ + throw new QRCodeDetectorException('could not find enough finder patterns'); + } + + usort( + $this->possibleCenters, + fn(FinderPattern $a, FinderPattern $b) => ($a->getEstimatedModuleSize() <=> $b->getEstimatedModuleSize()) + ); + + $distortion = PHP_FLOAT_MAX; + $bestPatterns = []; + + for($i = 0; $i < ($startSize - 2); $i++){ + $fpi = $this->possibleCenters[$i]; + $minModuleSize = $fpi->getEstimatedModuleSize(); + + for($j = ($i + 1); $j < ($startSize - 1); $j++){ + $fpj = $this->possibleCenters[$j]; + $squares0 = $fpi->getSquaredDistance($fpj); + + for($k = ($j + 1); $k < $startSize; $k++){ + $fpk = $this->possibleCenters[$k]; + $maxModuleSize = $fpk->getEstimatedModuleSize(); + + // module size is not similar + if($maxModuleSize > ($minModuleSize * 1.4)){ + continue; + } + + $a = $squares0; + $b = $fpj->getSquaredDistance($fpk); + $c = $fpi->getSquaredDistance($fpk); + + // sorts ascending - inlined + if($a < $b){ + if($b > $c){ + if($a < $c){ + $temp = $b; + $b = $c; + $c = $temp; + } + else{ + $temp = $a; + $a = $c; + $c = $b; + $b = $temp; + } + } + } + else{ + if($b < $c){ + if($a < $c){ + $temp = $a; + $a = $b; + $b = $temp; + } + else{ + $temp = $a; + $a = $b; + $b = $c; + $c = $temp; + } + } + else{ + $temp = $a; + $a = $c; + $c = $temp; + } + } + + // a^2 + b^2 = c^2 (Pythagorean theorem), and a = b (isosceles triangle). + // Since any right triangle satisfies the formula c^2 - b^2 - a^2 = 0, + // we need to check both two equal sides separately. + // The value of |c^2 - 2 * b^2| + |c^2 - 2 * a^2| increases as dissimilarity + // from isosceles right triangle. + $d = (abs($c - 2 * $b) + abs($c - 2 * $a)); + + if($d < $distortion){ + $distortion = $d; + $bestPatterns = [$fpi, $fpj, $fpk]; + } + } + } + } + + if($distortion === PHP_FLOAT_MAX){ + throw new QRCodeDetectorException('finder patterns may be too distorted'); + } + + return $bestPatterns; + } + + /** + * Orders an array of three ResultPoints in an order [A,B,C] such that AB is less than AC + * and BC is less than AC, and the angle between BC and BA is less than 180 degrees. + * + * @param \chillerlan\QRCode\Detector\FinderPattern[] $patterns array of three FinderPattern to order + * + * @return \chillerlan\QRCode\Detector\FinderPattern[] + */ + private function orderBestPatterns(array $patterns):array{ + + // Find distances between pattern centers + $zeroOneDistance = $patterns[0]->getDistance($patterns[1]); + $oneTwoDistance = $patterns[1]->getDistance($patterns[2]); + $zeroTwoDistance = $patterns[0]->getDistance($patterns[2]); + + // Assume one closest to other two is B; A and C will just be guesses at first + if($oneTwoDistance >= $zeroOneDistance && $oneTwoDistance >= $zeroTwoDistance){ + [$pointB, $pointA, $pointC] = $patterns; + } + elseif($zeroTwoDistance >= $oneTwoDistance && $zeroTwoDistance >= $zeroOneDistance){ + [$pointA, $pointB, $pointC] = $patterns; + } + else{ + [$pointA, $pointC, $pointB] = $patterns; + } + + // Use cross product to figure out whether A and C are correct or flipped. + // This asks whether BC x BA has a positive z component, which is the arrangement + // we want for A, B, C. If it's negative, then we've got it flipped around and + // should swap A and C. + if($this->crossProductZ($pointA, $pointB, $pointC) < 0.0){ + $temp = $pointA; + $pointA = $pointC; + $pointC = $temp; + } + + return [$pointA, $pointB, $pointC]; + } + + /** + * Returns the z component of the cross product between vectors BC and BA. + */ + private function crossProductZ(FinderPattern $pointA, FinderPattern $pointB, FinderPattern $pointC):float{ + $bX = $pointB->getX(); + $bY = $pointB->getY(); + + return ((($pointC->getX() - $bX) * ($pointA->getY() - $bY)) - (($pointC->getY() - $bY) * ($pointA->getX() - $bX))); + } + +} |