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<?php |
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/** |
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* Class FinderPatternFinder |
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* |
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* @created 17.01.2021 |
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* @author ZXing Authors |
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* @author Smiley <[email protected]> |
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* @copyright 2021 Smiley |
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* @license Apache-2.0 |
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* |
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* @phan-file-suppress PhanTypePossiblyInvalidDimOffset |
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*/ |
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namespace chillerlan\QRCode\Detector; |
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use RuntimeException; |
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use chillerlan\QRCode\Decoder\BitMatrix; |
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use function abs, count, usort; |
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use const PHP_FLOAT_MAX; |
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/** |
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* <p>This class attempts to find finder patterns in a QR Code. Finder patterns are the square |
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* markers at three corners of a QR Code.</p> |
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* |
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* <p>This class is thread-safe but not reentrant. Each thread must allocate its own object. |
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* |
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* @author Sean Owen |
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*/ |
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final class FinderPatternFinder{ |
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private const MIN_SKIP = 2; |
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private const MAX_MODULES = 177; // 1 pixel/module times 3 modules/center |
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private const CENTER_QUORUM = 2; // support up to version 10 for mobile clients |
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private BitMatrix $bitMatrix; |
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/** @var \chillerlan\QRCode\Detector\FinderPattern[] */ |
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private array $possibleCenters; |
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private bool $hasSkipped = false; |
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/** @var int[] */ |
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private array $crossCheckStateCount; |
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/** |
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* <p>Creates a finder that will search the image for three finder patterns.</p> |
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* |
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* @param BitMatrix $bitMatrix image to search |
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*/ |
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public function __construct(BitMatrix $bitMatrix){ |
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$this->bitMatrix = $bitMatrix; |
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$this->possibleCenters = []; |
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$this->crossCheckStateCount = $this->getCrossCheckStateCount(); |
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} |
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/** |
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* @return \chillerlan\QRCode\Detector\FinderPattern[] |
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*/ |
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public function find():array{ |
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$dimension = $this->bitMatrix->getDimension(); |
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// We are looking for black/white/black/white/black modules in |
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// 1:1:3:1:1 ratio; this tracks the number of such modules seen so far |
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// Let's assume that the maximum version QR Code we support takes up 1/4 the height of the |
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// image, and then account for the center being 3 modules in size. This gives the smallest |
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// number of pixels the center could be, so skip this often. |
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$iSkip = (int)((3 * $dimension) / (4 * self::MAX_MODULES)); |
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if($iSkip < self::MIN_SKIP){ |
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$iSkip = self::MIN_SKIP; |
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} |
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$done = false; |
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for($i = $iSkip - 1; $i < $dimension && !$done; $i += $iSkip){ |
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// Get a row of black/white values |
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$stateCount = $this->getCrossCheckStateCount(); |
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$currentState = 0; |
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for($j = 0; $j < $dimension; $j++){ |
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// Black pixel |
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if($this->bitMatrix->get($j, $i)){ |
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// Counting white pixels |
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if(($currentState & 1) === 1){ |
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$currentState++; |
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} |
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$stateCount[$currentState]++; |
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} |
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// White pixel |
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else{ |
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// Counting black pixels |
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if(($currentState & 1) === 0){ |
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// A winner? |
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if($currentState === 4){ |
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// Yes |
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if($this->foundPatternCross($stateCount)){ |
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$confirmed = $this->handlePossibleCenter($stateCount, $i, $j); |
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if($confirmed){ |
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// Start examining every other line. Checking each line turned out to be too |
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// expensive and didn't improve performance. |
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$iSkip = 3; |
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if($this->hasSkipped){ |
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$done = $this->haveMultiplyConfirmedCenters(); |
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} |
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else{ |
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$rowSkip = $this->findRowSkip(); |
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if($rowSkip > $stateCount[2]){ |
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// Skip rows between row of lower confirmed center |
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// and top of presumed third confirmed center |
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// but back up a bit to get a full chance of detecting |
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// it, entire width of center of finder pattern |
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// Skip by rowSkip, but back off by $stateCount[2] (size of last center |
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// of pattern we saw) to be conservative, and also back off by iSkip which |
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// is about to be re-added |
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$i += $rowSkip - $stateCount[2] - $iSkip; |
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$j = $dimension - 1; |
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} |
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} |
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} |
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else{ |
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$stateCount = $this->doShiftCounts2($stateCount); |
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$currentState = 3; |
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continue; |
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} |
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// Clear state to start looking again |
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$currentState = 0; |
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$stateCount = $this->getCrossCheckStateCount(); |
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} |
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// No, shift counts back by two |
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else{ |
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$stateCount = $this->doShiftCounts2($stateCount); |
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$currentState = 3; |
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} |
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} |
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else{ |
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$stateCount[++$currentState]++; |
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} |
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} |
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// Counting white pixels |
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else{ |
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$stateCount[$currentState]++; |
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} |
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} |
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} |
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if($this->foundPatternCross($stateCount)){ |
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$confirmed = $this->handlePossibleCenter($stateCount, $i, $dimension); |
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if($confirmed){ |
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$iSkip = $stateCount[0]; |
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if($this->hasSkipped){ |
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// Found a third one |
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$done = $this->haveMultiplyConfirmedCenters(); |
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} |
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} |
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} |
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} |
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return $this->orderBestPatterns($this->selectBestPatterns()); |
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} |
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/** |
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* @return int[] |
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*/ |
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private function getCrossCheckStateCount():array{ |
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return [0, 0, 0, 0, 0]; |
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} |
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/** |
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* @param int[] $stateCount |
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* |
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* @return int[] |
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*/ |
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private function doShiftCounts2(array $stateCount):array{ |
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$stateCount[0] = $stateCount[2]; |
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$stateCount[1] = $stateCount[3]; |
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$stateCount[2] = $stateCount[4]; |
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$stateCount[3] = 1; |
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$stateCount[4] = 0; |
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return $stateCount; |
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} |
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/** |
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* Given a count of black/white/black/white/black pixels just seen and an end position, |
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* figures the location of the center of this run. |
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* |
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* @param int[] $stateCount |
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* |
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* @return float |
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*/ |
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private function centerFromEnd(array $stateCount, int $end):float{ |
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return (float)(($end - $stateCount[4] - $stateCount[3]) - $stateCount[2] / 2.0); |
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} |
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/** |
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* @param int[] $stateCount |
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* |
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* @return bool |
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*/ |
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private function foundPatternCross(array $stateCount):bool{ |
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// Allow less than 50% variance from 1-1-3-1-1 proportions |
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return $this->foundPatternVariance($stateCount, 2.0); |
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} |
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/** |
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* @param int[] $stateCount |
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* |
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* @return bool |
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*/ |
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private function foundPatternDiagonal(array $stateCount):bool{ |
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// Allow less than 75% variance from 1-1-3-1-1 proportions |
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return $this->foundPatternVariance($stateCount, 1.333); |
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} |
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/** |
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* @param int[] $stateCount count of black/white/black/white/black pixels just read |
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* |
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* @return bool true if the proportions of the counts is close enough to the 1/1/3/1/1 ratios |
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* used by finder patterns to be considered a match |
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*/ |
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private function foundPatternVariance(array $stateCount, float $variance):bool{ |
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$totalModuleSize = 0; |
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for($i = 0; $i < 5; $i++){ |
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$count = $stateCount[$i]; |
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if($count === 0){ |
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return false; |
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} |
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$totalModuleSize += $count; |
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} |
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if($totalModuleSize < 7){ |
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return false; |
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} |
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$moduleSize = $totalModuleSize / 7.0; |
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$maxVariance = $moduleSize / $variance; |
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return |
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abs($moduleSize - $stateCount[0]) < $maxVariance |
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&& abs($moduleSize - $stateCount[1]) < $maxVariance |
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&& abs(3.0 * $moduleSize - $stateCount[2]) < 3 * $maxVariance |
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&& abs($moduleSize - $stateCount[3]) < $maxVariance |
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&& abs($moduleSize - $stateCount[4]) < $maxVariance; |
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} |
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/** |
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* After a vertical and horizontal scan finds a potential finder pattern, this method |
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* "cross-cross-cross-checks" by scanning down diagonally through the center of the possible |
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* finder pattern to see if the same proportion is detected. |
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* |
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* @param $centerI ; row where a finder pattern was detected |
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* @param $centerJ ; center of the section that appears to cross a finder pattern |
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* |
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* @return bool true if proportions are withing expected limits |
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*/ |
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private function crossCheckDiagonal(int $centerI, int $centerJ):bool{ |
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$stateCount = $this->getCrossCheckStateCount(); |
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// Start counting up, left from center finding black center mass |
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$i = 0; |
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while($centerI >= $i && $centerJ >= $i && $this->bitMatrix->get($centerJ - $i, $centerI - $i)){ |
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$stateCount[2]++; |
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$i++; |
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} |
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if($stateCount[2] === 0){ |
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return false; |
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} |
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// Continue up, left finding white space |
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while($centerI >= $i && $centerJ >= $i && !$this->bitMatrix->get($centerJ - $i, $centerI - $i)){ |
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$stateCount[1]++; |
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$i++; |
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} |
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if($stateCount[1] === 0){ |
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return false; |
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} |
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// Continue up, left finding black border |
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while($centerI >= $i && $centerJ >= $i && $this->bitMatrix->get($centerJ - $i, $centerI - $i)){ |
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$stateCount[0]++; |
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$i++; |
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} |
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if($stateCount[0] === 0){ |
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return false; |
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} |
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$dimension = $this->bitMatrix->getDimension(); |
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// Now also count down, right from center |
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$i = 1; |
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while($centerI + $i < $dimension && $centerJ + $i < $dimension && $this->bitMatrix->get($centerJ + $i, $centerI + $i)){ |
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$stateCount[2]++; |
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$i++; |
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} |
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while($centerI + $i < $dimension && $centerJ + $i < $dimension && !$this->bitMatrix->get($centerJ + $i, $centerI + $i)){ |
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$stateCount[3]++; |
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$i++; |
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} |
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if($stateCount[3] === 0){ |
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return false; |
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} |
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while($centerI + $i < $dimension && $centerJ + $i < $dimension && $this->bitMatrix->get($centerJ + $i, $centerI + $i)){ |
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$stateCount[4]++; |
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$i++; |
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} |
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if($stateCount[4] === 0){ |
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return false; |
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} |
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return $this->foundPatternDiagonal($stateCount); |
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} |
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/** |
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* <p>After a horizontal scan finds a potential finder pattern, this method |
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* "cross-checks" by scanning down vertically through the center of the possible |
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* finder pattern to see if the same proportion is detected.</p> |
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* |
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* @param int $startI ; row where a finder pattern was detected |
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* @param int $centerJ ; center of the section that appears to cross a finder pattern |
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* @param int $maxCount ; maximum reasonable number of modules that should be |
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* observed in any reading state, based on the results of the horizontal scan |
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* @param int $originalStateCountTotal |
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* |
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* @return float|null vertical center of finder pattern, or null if not found |
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*/ |
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private function crossCheckVertical(int $startI, int $centerJ, int $maxCount, int $originalStateCountTotal):?float{ |
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$maxI = $this->bitMatrix->getDimension(); |
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$stateCount = $this->getCrossCheckStateCount(); |
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// Start counting up from center |
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$i = $startI; |
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while($i >= 0 && $this->bitMatrix->get($centerJ, $i)){ |
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$stateCount[2]++; |
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$i--; |
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} |
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if($i < 0){ |
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return null; |
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} |
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while($i >= 0 && !$this->bitMatrix->get($centerJ, $i) && $stateCount[1] <= $maxCount){ |
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$stateCount[1]++; |
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$i--; |
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} |
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// If already too many modules in this state or ran off the edge: |
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if($i < 0 || $stateCount[1] > $maxCount){ |
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return null; |
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} |
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|
|
while($i >= 0 && $this->bitMatrix->get($centerJ, $i) && $stateCount[0] <= $maxCount){ |
368
|
|
|
$stateCount[0]++; |
369
|
|
|
$i--; |
370
|
|
|
} |
371
|
|
|
|
372
|
|
|
if($stateCount[0] > $maxCount){ |
373
|
|
|
return null; |
374
|
|
|
} |
375
|
|
|
|
376
|
|
|
// Now also count down from center |
377
|
|
|
$i = $startI + 1; |
378
|
|
|
while($i < $maxI && $this->bitMatrix->get($centerJ, $i)){ |
379
|
|
|
$stateCount[2]++; |
380
|
|
|
$i++; |
381
|
|
|
} |
382
|
|
|
|
383
|
|
|
if($i === $maxI){ |
384
|
|
|
return null; |
385
|
|
|
} |
386
|
|
|
|
387
|
|
|
while($i < $maxI && !$this->bitMatrix->get($centerJ, $i) && $stateCount[3] < $maxCount){ |
388
|
|
|
$stateCount[3]++; |
389
|
|
|
$i++; |
390
|
|
|
} |
391
|
|
|
|
392
|
|
|
if($i === $maxI || $stateCount[3] >= $maxCount){ |
393
|
|
|
return null; |
394
|
|
|
} |
395
|
|
|
|
396
|
|
|
while($i < $maxI && $this->bitMatrix->get($centerJ, $i) && $stateCount[4] < $maxCount){ |
397
|
|
|
$stateCount[4]++; |
398
|
|
|
$i++; |
399
|
|
|
} |
400
|
|
|
|
401
|
|
|
if($stateCount[4] >= $maxCount){ |
402
|
|
|
return null; |
403
|
|
|
} |
404
|
|
|
|
405
|
|
|
// If we found a finder-pattern-like section, but its size is more than 40% different than |
406
|
|
|
// the original, assume it's a false positive |
407
|
|
|
$stateCountTotal = $stateCount[0] + $stateCount[1] + $stateCount[2] + $stateCount[3] + $stateCount[4]; |
408
|
|
|
|
409
|
|
|
if(5 * abs($stateCountTotal - $originalStateCountTotal) >= 2 * $originalStateCountTotal){ |
410
|
|
|
return null; |
411
|
|
|
} |
412
|
|
|
|
413
|
|
|
if(!$this->foundPatternCross($stateCount)){ |
414
|
|
|
return null; |
415
|
|
|
} |
416
|
|
|
|
417
|
|
|
return $this->centerFromEnd($stateCount, $i); |
418
|
|
|
} |
419
|
|
|
|
420
|
|
|
/** |
421
|
|
|
* <p>Like {@link #crossCheckVertical(int, int, int, int)}, and in fact is basically identical, |
422
|
|
|
* except it reads horizontally instead of vertically. This is used to cross-cross |
423
|
|
|
* check a vertical cross check and locate the real center of the alignment pattern.</p> |
424
|
|
|
*/ |
425
|
|
|
private function crossCheckHorizontal(int $startJ, int $centerI, int $maxCount, int $originalStateCountTotal):?float{ |
426
|
|
|
$maxJ = $this->bitMatrix->getDimension(); |
427
|
|
|
$stateCount = $this->getCrossCheckStateCount(); |
428
|
|
|
|
429
|
|
|
$j = $startJ; |
430
|
|
|
while($j >= 0 && $this->bitMatrix->get($j, $centerI)){ |
431
|
|
|
$stateCount[2]++; |
432
|
|
|
$j--; |
433
|
|
|
} |
434
|
|
|
|
435
|
|
|
if($j < 0){ |
436
|
|
|
return null; |
437
|
|
|
} |
438
|
|
|
|
439
|
|
|
while($j >= 0 && !$this->bitMatrix->get($j, $centerI) && $stateCount[1] <= $maxCount){ |
440
|
|
|
$stateCount[1]++; |
441
|
|
|
$j--; |
442
|
|
|
} |
443
|
|
|
|
444
|
|
|
if($j < 0 || $stateCount[1] > $maxCount){ |
445
|
|
|
return null; |
446
|
|
|
} |
447
|
|
|
|
448
|
|
|
while($j >= 0 && $this->bitMatrix->get($j, $centerI) && $stateCount[0] <= $maxCount){ |
449
|
|
|
$stateCount[0]++; |
450
|
|
|
$j--; |
451
|
|
|
} |
452
|
|
|
|
453
|
|
|
if($stateCount[0] > $maxCount){ |
454
|
|
|
return null; |
455
|
|
|
} |
456
|
|
|
|
457
|
|
|
$j = $startJ + 1; |
458
|
|
|
while($j < $maxJ && $this->bitMatrix->get($j, $centerI)){ |
459
|
|
|
$stateCount[2]++; |
460
|
|
|
$j++; |
461
|
|
|
} |
462
|
|
|
|
463
|
|
|
if($j === $maxJ){ |
464
|
|
|
return null; |
465
|
|
|
} |
466
|
|
|
|
467
|
|
|
while($j < $maxJ && !$this->bitMatrix->get($j, $centerI) && $stateCount[3] < $maxCount){ |
468
|
|
|
$stateCount[3]++; |
469
|
|
|
$j++; |
470
|
|
|
} |
471
|
|
|
|
472
|
|
|
if($j === $maxJ || $stateCount[3] >= $maxCount){ |
473
|
|
|
return null; |
474
|
|
|
} |
475
|
|
|
|
476
|
|
|
while($j < $maxJ && $this->bitMatrix->get($j, $centerI) && $stateCount[4] < $maxCount){ |
477
|
|
|
$stateCount[4]++; |
478
|
|
|
$j++; |
479
|
|
|
} |
480
|
|
|
|
481
|
|
|
if($stateCount[4] >= $maxCount){ |
482
|
|
|
return null; |
483
|
|
|
} |
484
|
|
|
|
485
|
|
|
// If we found a finder-pattern-like section, but its size is significantly different than |
486
|
|
|
// the original, assume it's a false positive |
487
|
|
|
$stateCountTotal = $stateCount[0] + $stateCount[1] + $stateCount[2] + $stateCount[3] + $stateCount[4]; |
488
|
|
|
|
489
|
|
|
if(5 * abs($stateCountTotal - $originalStateCountTotal) >= $originalStateCountTotal){ |
490
|
|
|
return null; |
491
|
|
|
} |
492
|
|
|
|
493
|
|
|
if(!$this->foundPatternCross($stateCount)){ |
494
|
|
|
return null; |
495
|
|
|
} |
496
|
|
|
|
497
|
|
|
return $this->centerFromEnd($stateCount, $j); |
498
|
|
|
} |
499
|
|
|
|
500
|
|
|
/** |
501
|
|
|
* <p>This is called when a horizontal scan finds a possible alignment pattern. It will |
502
|
|
|
* cross check with a vertical scan, and if successful, will, ah, cross-cross-check |
503
|
|
|
* with another horizontal scan. This is needed primarily to locate the real horizontal |
504
|
|
|
* center of the pattern in cases of extreme skew. |
505
|
|
|
* And then we cross-cross-cross check with another diagonal scan.</p> |
506
|
|
|
* |
507
|
|
|
* <p>If that succeeds the finder pattern location is added to a list that tracks |
508
|
|
|
* the number of times each location has been nearly-matched as a finder pattern. |
509
|
|
|
* Each additional find is more evidence that the location is in fact a finder |
510
|
|
|
* pattern center |
511
|
|
|
* |
512
|
|
|
* @param int[] $stateCount reading state module counts from horizontal scan |
513
|
|
|
* @param int $i row where finder pattern may be found |
514
|
|
|
* @param int $j end of possible finder pattern in row |
515
|
|
|
* |
516
|
|
|
* @return bool if a finder pattern candidate was found this time |
517
|
|
|
*/ |
518
|
|
|
private function handlePossibleCenter(array $stateCount, int $i, int $j):bool{ |
519
|
|
|
$stateCountTotal = $stateCount[0] + $stateCount[1] + $stateCount[2] + $stateCount[3] + $stateCount[4]; |
520
|
|
|
$centerJ = $this->centerFromEnd($stateCount, $j); |
521
|
|
|
$centerI = $this->crossCheckVertical($i, (int)$centerJ, $stateCount[2], $stateCountTotal); |
522
|
|
|
|
523
|
|
|
if($centerI !== null){ |
524
|
|
|
// Re-cross check |
525
|
|
|
$centerJ = $this->crossCheckHorizontal((int)$centerJ, (int)$centerI, $stateCount[2], $stateCountTotal); |
526
|
|
|
if($centerJ !== null && ($this->crossCheckDiagonal((int)$centerI, (int)$centerJ))){ |
527
|
|
|
$estimatedModuleSize = $stateCountTotal / 7.0; |
528
|
|
|
$found = false; |
529
|
|
|
|
530
|
|
|
for($index = 0; $index < count($this->possibleCenters); $index++){ |
|
|
|
|
531
|
|
|
$center = $this->possibleCenters[$index]; |
532
|
|
|
// Look for about the same center and module size: |
533
|
|
|
if($center->aboutEquals($estimatedModuleSize, $centerI, $centerJ)){ |
534
|
|
|
$this->possibleCenters[$index] = $center->combineEstimate($centerI, $centerJ, $estimatedModuleSize); |
535
|
|
|
$found = true; |
536
|
|
|
break; |
537
|
|
|
} |
538
|
|
|
} |
539
|
|
|
|
540
|
|
|
if(!$found){ |
541
|
|
|
$point = new FinderPattern($centerJ, $centerI, $estimatedModuleSize); |
542
|
|
|
$this->possibleCenters[] = $point; |
543
|
|
|
} |
544
|
|
|
|
545
|
|
|
return true; |
546
|
|
|
} |
547
|
|
|
} |
548
|
|
|
|
549
|
|
|
return false; |
550
|
|
|
} |
551
|
|
|
|
552
|
|
|
/** |
553
|
|
|
* @return int number of rows we could safely skip during scanning, based on the first |
554
|
|
|
* two finder patterns that have been located. In some cases their position will |
555
|
|
|
* allow us to infer that the third pattern must lie below a certain point farther |
556
|
|
|
* down in the image. |
557
|
|
|
*/ |
558
|
|
|
private function findRowSkip():int{ |
559
|
|
|
$max = count($this->possibleCenters); |
560
|
|
|
|
561
|
|
|
if($max <= 1){ |
562
|
|
|
return 0; |
563
|
|
|
} |
564
|
|
|
|
565
|
|
|
$firstConfirmedCenter = null; |
566
|
|
|
|
567
|
|
|
foreach($this->possibleCenters as $center){ |
568
|
|
|
|
569
|
|
|
if($center->getCount() >= self::CENTER_QUORUM){ |
570
|
|
|
|
571
|
|
|
if($firstConfirmedCenter === null){ |
572
|
|
|
$firstConfirmedCenter = $center; |
573
|
|
|
} |
574
|
|
|
else{ |
575
|
|
|
// We have two confirmed centers |
576
|
|
|
// How far down can we skip before resuming looking for the next |
577
|
|
|
// pattern? In the worst case, only the difference between the |
578
|
|
|
// difference in the x / y coordinates of the two centers. |
579
|
|
|
// This is the case where you find top left last. |
580
|
|
|
$this->hasSkipped = true; |
581
|
|
|
|
582
|
|
|
return (int)((abs($firstConfirmedCenter->getX() - $center->getX()) - |
|
|
|
|
583
|
|
|
abs($firstConfirmedCenter->getY() - $center->getY())) / 2); |
584
|
|
|
} |
585
|
|
|
} |
586
|
|
|
} |
587
|
|
|
|
588
|
|
|
return 0; |
589
|
|
|
} |
590
|
|
|
|
591
|
|
|
/** |
592
|
|
|
* @return bool true if we have found at least 3 finder patterns that have been detected |
593
|
|
|
* at least {@link #CENTER_QUORUM} times each, and, the estimated module size of the |
594
|
|
|
* candidates is "pretty similar" |
595
|
|
|
*/ |
596
|
|
|
private function haveMultiplyConfirmedCenters():bool{ |
597
|
|
|
$confirmedCount = 0; |
598
|
|
|
$totalModuleSize = 0.0; |
599
|
|
|
$max = count($this->possibleCenters); |
600
|
|
|
|
601
|
|
|
foreach($this->possibleCenters as $pattern){ |
602
|
|
|
if($pattern->getCount() >= self::CENTER_QUORUM){ |
603
|
|
|
$confirmedCount++; |
604
|
|
|
$totalModuleSize += $pattern->getEstimatedModuleSize(); |
605
|
|
|
} |
606
|
|
|
} |
607
|
|
|
|
608
|
|
|
if($confirmedCount < 3){ |
609
|
|
|
return false; |
610
|
|
|
} |
611
|
|
|
// OK, we have at least 3 confirmed centers, but, it's possible that one is a "false positive" |
612
|
|
|
// and that we need to keep looking. We detect this by asking if the estimated module sizes |
613
|
|
|
// vary too much. We arbitrarily say that when the total deviation from average exceeds |
614
|
|
|
// 5% of the total module size estimates, it's too much. |
615
|
|
|
$average = $totalModuleSize / (float)$max; |
616
|
|
|
$totalDeviation = 0.0; |
617
|
|
|
|
618
|
|
|
foreach($this->possibleCenters as $pattern){ |
619
|
|
|
$totalDeviation += abs($pattern->getEstimatedModuleSize() - $average); |
620
|
|
|
} |
621
|
|
|
|
622
|
|
|
return $totalDeviation <= 0.05 * $totalModuleSize; |
623
|
|
|
} |
624
|
|
|
|
625
|
|
|
/** |
626
|
|
|
* @return \chillerlan\QRCode\Detector\FinderPattern[] the 3 best {@link FinderPattern}s from our list of candidates. The "best" are |
627
|
|
|
* those that have been detected at least {@link #CENTER_QUORUM} times, and whose module |
628
|
|
|
* size differs from the average among those patterns the least |
629
|
|
|
* @throws \RuntimeException if 3 such finder patterns do not exist |
630
|
|
|
*/ |
631
|
|
|
private function selectBestPatterns():array{ |
632
|
|
|
$startSize = count($this->possibleCenters); |
633
|
|
|
|
634
|
|
|
if($startSize < 3){ |
635
|
|
|
throw new RuntimeException('could not find enough finder patterns'); |
636
|
|
|
} |
637
|
|
|
|
638
|
|
|
usort( |
639
|
|
|
$this->possibleCenters, |
640
|
|
|
fn(FinderPattern $a, FinderPattern $b) => $a->getEstimatedModuleSize() <=> $b->getEstimatedModuleSize() |
641
|
|
|
); |
642
|
|
|
|
643
|
|
|
$distortion = PHP_FLOAT_MAX; |
644
|
|
|
$bestPatterns = []; |
645
|
|
|
|
646
|
|
|
for($i = 0; $i < $startSize - 2; $i++){ |
647
|
|
|
$fpi = $this->possibleCenters[$i]; |
648
|
|
|
$minModuleSize = $fpi->getEstimatedModuleSize(); |
649
|
|
|
|
650
|
|
|
for($j = $i + 1; $j < $startSize - 1; $j++){ |
651
|
|
|
$fpj = $this->possibleCenters[$j]; |
652
|
|
|
$squares0 = $fpi->squaredDistance($fpj); |
653
|
|
|
|
654
|
|
|
for($k = $j + 1; $k < $startSize; $k++){ |
655
|
|
|
$fpk = $this->possibleCenters[$k]; |
656
|
|
|
$maxModuleSize = $fpk->getEstimatedModuleSize(); |
657
|
|
|
|
658
|
|
|
// module size is not similar |
659
|
|
|
if($maxModuleSize > $minModuleSize * 1.4){ |
660
|
|
|
continue; |
661
|
|
|
} |
662
|
|
|
|
663
|
|
|
$a = $squares0; |
664
|
|
|
$b = $fpj->squaredDistance($fpk); |
665
|
|
|
$c = $fpi->squaredDistance($fpk); |
666
|
|
|
|
667
|
|
|
// sorts ascending - inlined |
668
|
|
|
if($a < $b){ |
669
|
|
|
if($b > $c){ |
670
|
|
|
if($a < $c){ |
671
|
|
|
$temp = $b; |
672
|
|
|
$b = $c; |
673
|
|
|
$c = $temp; |
674
|
|
|
} |
675
|
|
|
else{ |
676
|
|
|
$temp = $a; |
677
|
|
|
$a = $c; |
678
|
|
|
$c = $b; |
679
|
|
|
$b = $temp; |
680
|
|
|
} |
681
|
|
|
} |
682
|
|
|
} |
683
|
|
|
else{ |
684
|
|
|
if($b < $c){ |
685
|
|
|
if($a < $c){ |
686
|
|
|
$temp = $a; |
687
|
|
|
$a = $b; |
688
|
|
|
$b = $temp; |
689
|
|
|
} |
690
|
|
|
else{ |
691
|
|
|
$temp = $a; |
692
|
|
|
$a = $b; |
693
|
|
|
$b = $c; |
694
|
|
|
$c = $temp; |
695
|
|
|
} |
696
|
|
|
} |
697
|
|
|
else{ |
698
|
|
|
$temp = $a; |
699
|
|
|
$a = $c; |
700
|
|
|
$c = $temp; |
701
|
|
|
} |
702
|
|
|
} |
703
|
|
|
|
704
|
|
|
// a^2 + b^2 = c^2 (Pythagorean theorem), and a = b (isosceles triangle). |
705
|
|
|
// Since any right triangle satisfies the formula c^2 - b^2 - a^2 = 0, |
706
|
|
|
// we need to check both two equal sides separately. |
707
|
|
|
// The value of |c^2 - 2 * b^2| + |c^2 - 2 * a^2| increases as dissimilarity |
708
|
|
|
// from isosceles right triangle. |
709
|
|
|
$d = abs($c - 2 * $b) + abs($c - 2 * $a); |
710
|
|
|
|
711
|
|
|
if($d < $distortion){ |
712
|
|
|
$distortion = $d; |
713
|
|
|
$bestPatterns = [$fpi, $fpj, $fpk]; |
714
|
|
|
} |
715
|
|
|
} |
716
|
|
|
} |
717
|
|
|
} |
718
|
|
|
|
719
|
|
|
if($distortion === PHP_FLOAT_MAX){ |
720
|
|
|
throw new RuntimeException('finder patterns may be too distorted'); |
721
|
|
|
} |
722
|
|
|
|
723
|
|
|
return $bestPatterns; |
724
|
|
|
} |
725
|
|
|
|
726
|
|
|
/** |
727
|
|
|
* Orders an array of three ResultPoints in an order [A,B,C] such that AB is less than AC |
728
|
|
|
* and BC is less than AC, and the angle between BC and BA is less than 180 degrees. |
729
|
|
|
* |
730
|
|
|
* @param \chillerlan\QRCode\Detector\FinderPattern[] $patterns array of three FinderPattern to order |
731
|
|
|
* |
732
|
|
|
* @return \chillerlan\QRCode\Detector\FinderPattern[] |
733
|
|
|
*/ |
734
|
|
|
private function orderBestPatterns(array $patterns):array{ |
735
|
|
|
|
736
|
|
|
// Find distances between pattern centers |
737
|
|
|
$zeroOneDistance = $patterns[0]->distance($patterns[1]); |
738
|
|
|
$oneTwoDistance = $patterns[1]->distance($patterns[2]); |
739
|
|
|
$zeroTwoDistance = $patterns[0]->distance($patterns[2]); |
740
|
|
|
|
741
|
|
|
// Assume one closest to other two is B; A and C will just be guesses at first |
742
|
|
|
if($oneTwoDistance >= $zeroOneDistance && $oneTwoDistance >= $zeroTwoDistance){ |
743
|
|
|
[$pointB, $pointA, $pointC] = $patterns; |
744
|
|
|
} |
745
|
|
|
elseif($zeroTwoDistance >= $oneTwoDistance && $zeroTwoDistance >= $zeroOneDistance){ |
746
|
|
|
[$pointA, $pointB, $pointC] = $patterns; |
747
|
|
|
} |
748
|
|
|
else{ |
749
|
|
|
[$pointA, $pointC, $pointB] = $patterns; |
750
|
|
|
} |
751
|
|
|
|
752
|
|
|
// Use cross product to figure out whether A and C are correct or flipped. |
753
|
|
|
// This asks whether BC x BA has a positive z component, which is the arrangement |
754
|
|
|
// we want for A, B, C. If it's negative, then we've got it flipped around and |
755
|
|
|
// should swap A and C. |
756
|
|
|
if($this->crossProductZ($pointA, $pointB, $pointC) < 0.0){ |
757
|
|
|
$temp = $pointA; |
758
|
|
|
$pointA = $pointC; |
759
|
|
|
$pointC = $temp; |
760
|
|
|
} |
761
|
|
|
|
762
|
|
|
return [$pointA, $pointB, $pointC]; |
763
|
|
|
} |
764
|
|
|
|
765
|
|
|
/** |
766
|
|
|
* Returns the z component of the cross product between vectors BC and BA. |
767
|
|
|
*/ |
768
|
|
|
private function crossProductZ(FinderPattern $pointA, FinderPattern $pointB, FinderPattern $pointC):float{ |
769
|
|
|
$bX = $pointB->getX(); |
770
|
|
|
$bY = $pointB->getY(); |
771
|
|
|
|
772
|
|
|
return (($pointC->getX() - $bX) * ($pointA->getY() - $bY)) - (($pointC->getY() - $bY) * ($pointA->getX() - $bX)); |
773
|
|
|
} |
774
|
|
|
|
775
|
|
|
} |
776
|
|
|
|