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<?php |
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|
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/** |
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* Class Detector |
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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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namespace WCPOS\Vendor\chillerlan\QRCode\Detector; |
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|
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use WCPOS\Vendor\chillerlan\QRCode\Common\LuminanceSourceInterface; |
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use WCPOS\Vendor\chillerlan\QRCode\Common\Version; |
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use WCPOS\Vendor\chillerlan\QRCode\Decoder\Binarizer; |
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use WCPOS\Vendor\chillerlan\QRCode\Decoder\BitMatrix; |
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use function abs, intdiv, is_nan, max, min, round; |
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use const NAN; |
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/** |
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* Encapsulates logic that can detect a QR Code in an image, even if the QR Code |
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* is rotated or skewed, or partially obscured. |
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* |
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* @author Sean Owen |
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*/ |
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final class Detector |
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{ |
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private BitMatrix $matrix; |
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/** @var \chillerlan\QRCode\Detector\FinderPattern[] */ |
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private array $finderPatterns = []; |
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/** |
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* Detector constructor. |
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*/ |
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public function __construct(LuminanceSourceInterface $source) |
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{ |
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$this->matrix = (new Binarizer($source))->getBlackMatrix(); |
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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 getFinderPatterns() : array |
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{ |
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return $this->finderPatterns; |
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} |
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/** |
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* Detects a QR Code in an image. |
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*/ |
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public function detect() : BitMatrix |
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{ |
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$this->finderPatterns = (new FinderPatternFinder($this->matrix))->find(); |
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[$bottomLeft, $topLeft, $topRight] = $this->finderPatterns; |
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$moduleSize = $this->calculateModuleSize($topLeft, $topRight, $bottomLeft); |
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$dimension = $this->computeDimension($topLeft, $topRight, $bottomLeft, $moduleSize); |
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$provisionalVersion = new Version(intdiv($dimension - 17, 4)); |
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$alignmentPattern = null; |
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// Anything above version 1 has an alignment pattern |
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if ($provisionalVersion->getAlignmentPattern() !== []) { |
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// Guess where a "bottom right" finder pattern would have been |
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$bottomRightX = $topRight->getX() - $topLeft->getX() + $bottomLeft->getX(); |
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$bottomRightY = $topRight->getY() - $topLeft->getY() + $bottomLeft->getY(); |
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// Estimate that alignment pattern is closer by 3 modules |
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// from "bottom right" to known top left location |
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$correctionToTopLeft = 1.0 - 3.0 / (float) ($provisionalVersion->getDimension() - 7); |
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$estAlignmentX = (int) ($topLeft->getX() + $correctionToTopLeft * ($bottomRightX - $topLeft->getX())); |
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$estAlignmentY = (int) ($topLeft->getY() + $correctionToTopLeft * ($bottomRightY - $topLeft->getY())); |
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// Kind of arbitrary -- expand search radius before giving up |
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for ($i = 4; $i <= 16; $i <<= 1) { |
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//?????????? |
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$alignmentPattern = $this->findAlignmentInRegion($moduleSize, $estAlignmentX, $estAlignmentY, (float) $i); |
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if ($alignmentPattern !== null) { |
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break; |
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} |
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} |
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// If we didn't find alignment pattern... well try anyway without it |
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} |
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$transform = $this->createTransform($topLeft, $topRight, $bottomLeft, $dimension, $alignmentPattern); |
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return (new GridSampler())->sampleGrid($this->matrix, $dimension, $transform); |
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} |
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/** |
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* Computes an average estimated module size based on estimated derived from the positions |
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* of the three finder patterns. |
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* |
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* @throws \chillerlan\QRCode\Detector\QRCodeDetectorException |
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*/ |
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private function calculateModuleSize(FinderPattern $topLeft, FinderPattern $topRight, FinderPattern $bottomLeft) : float |
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{ |
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// Take the average |
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$moduleSize = ($this->calculateModuleSizeOneWay($topLeft, $topRight) + $this->calculateModuleSizeOneWay($topLeft, $bottomLeft)) / 2.0; |
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if ($moduleSize < 1.0) { |
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throw new QRCodeDetectorException('module size < 1.0'); |
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} |
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return $moduleSize; |
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} |
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/** |
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* Estimates module size based on two finder patterns -- it uses |
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* #sizeOfBlackWhiteBlackRunBothWays(int, int, int, int) to figure the |
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* width of each, measuring along the axis between their centers. |
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*/ |
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private function calculateModuleSizeOneWay(FinderPattern $a, FinderPattern $b) : float |
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{ |
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$moduleSizeEst1 = $this->sizeOfBlackWhiteBlackRunBothWays($a->getX(), $a->getY(), $b->getX(), $b->getY()); |
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$moduleSizeEst2 = $this->sizeOfBlackWhiteBlackRunBothWays($b->getX(), $b->getY(), $a->getX(), $a->getY()); |
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if (is_nan($moduleSizeEst1)) { |
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return $moduleSizeEst2 / 7.0; |
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} |
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if (is_nan($moduleSizeEst2)) { |
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return $moduleSizeEst1 / 7.0; |
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} |
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// Average them, and divide by 7 since we've counted the width of 3 black modules, |
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// and 1 white and 1 black module on either side. Ergo, divide sum by 14. |
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return ($moduleSizeEst1 + $moduleSizeEst2) / 14.0; |
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} |
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/** |
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* See #sizeOfBlackWhiteBlackRun(int, int, int, int); computes the total width of |
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* a finder pattern by looking for a black-white-black run from the center in the direction |
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* of another po$(another finder pattern center), and in the opposite direction too. |
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* |
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* @noinspection DuplicatedCode |
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*/ |
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private function sizeOfBlackWhiteBlackRunBothWays(float $fromX, float $fromY, float $toX, float $toY) : float |
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{ |
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$result = $this->sizeOfBlackWhiteBlackRun((int) $fromX, (int) $fromY, (int) $toX, (int) $toY); |
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$dimension = $this->matrix->getSize(); |
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// Now count other way -- don't run off image though of course |
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$scale = 1.0; |
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$otherToX = $fromX - ($toX - $fromX); |
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if ($otherToX < 0) { |
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$scale = $fromX / ($fromX - $otherToX); |
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$otherToX = 0; |
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} elseif ($otherToX >= $dimension) { |
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$scale = ($dimension - 1 - $fromX) / ($otherToX - $fromX); |
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$otherToX = $dimension - 1; |
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} |
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$otherToY = (int) ($fromY - ($toY - $fromY) * $scale); |
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$scale = 1.0; |
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if ($otherToY < 0) { |
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$scale = $fromY / ($fromY - $otherToY); |
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$otherToY = 0; |
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} elseif ($otherToY >= $dimension) { |
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$scale = ($dimension - 1 - $fromY) / ($otherToY - $fromY); |
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$otherToY = $dimension - 1; |
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} |
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$otherToX = (int) ($fromX + ($otherToX - $fromX) * $scale); |
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$result += $this->sizeOfBlackWhiteBlackRun((int) $fromX, (int) $fromY, $otherToX, $otherToY); |
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// Middle pixel is double-counted this way; subtract 1 |
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return $result - 1.0; |
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} |
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/** |
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* This method traces a line from a po$in the image, in the direction towards another point. |
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* It begins in a black region, and keeps going until it finds white, then black, then white again. |
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* It reports the distance from the start to this point. |
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* |
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* This is used when figuring out how wide a finder pattern is, when the finder pattern |
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* may be skewed or rotated. |
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*/ |
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private function sizeOfBlackWhiteBlackRun(int $fromX, int $fromY, int $toX, int $toY) : float |
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{ |
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// Mild variant of Bresenham's algorithm; |
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// @see https://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm |
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$steep = abs($toY - $fromY) > abs($toX - $fromX); |
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if ($steep) { |
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$temp = $fromX; |
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$fromX = $fromY; |
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$fromY = $temp; |
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$temp = $toX; |
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$toX = $toY; |
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$toY = $temp; |
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} |
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$dx = abs($toX - $fromX); |
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$dy = abs($toY - $fromY); |
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$error = -$dx / 2; |
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$xstep = $fromX < $toX ? 1 : -1; |
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$ystep = $fromY < $toY ? 1 : -1; |
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// In black pixels, looking for white, first or second time. |
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$state = 0; |
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// Loop up until x == toX, but not beyond |
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$xLimit = $toX + $xstep; |
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for ($x = $fromX, $y = $fromY; $x !== $xLimit; $x += $xstep) { |
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$realX = $steep ? $y : $x; |
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$realY = $steep ? $x : $y; |
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// Does current pixel mean we have moved white to black or vice versa? |
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// Scanning black in state 0,2 and white in state 1, so if we find the wrong |
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// color, advance to next state or end if we are in state 2 already |
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if (($state === 1) === $this->matrix->check($realX, $realY)) { |
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if ($state === 2) { |
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return FinderPattern::distance($x, $y, $fromX, $fromY); |
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} |
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$state++; |
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} |
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$error += $dy; |
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if ($error > 0) { |
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if ($y === $toY) { |
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break; |
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} |
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$y += $ystep; |
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$error -= $dx; |
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} |
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} |
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// Found black-white-black; give the benefit of the doubt that the next pixel outside the image |
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// is "white" so this last po$at (toX+xStep,toY) is the right ending. This is really a |
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// small approximation; (toX+xStep,toY+yStep) might be really correct. Ignore this. |
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if ($state === 2) { |
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return FinderPattern::distance($toX + $xstep, $toY, $fromX, $fromY); |
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} |
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// else we didn't find even black-white-black; no estimate is really possible |
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return NAN; |
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} |
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/** |
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* Computes the dimension (number of modules on a size) of the QR Code based on the position |
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* of the finder patterns and estimated module size. |
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* |
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* @throws \chillerlan\QRCode\Detector\QRCodeDetectorException |
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*/ |
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private function computeDimension(FinderPattern $nw, FinderPattern $ne, FinderPattern $sw, float $size) : int |
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{ |
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$tltrCentersDimension = (int) round($nw->getDistance($ne) / $size); |
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$tlblCentersDimension = (int) round($nw->getDistance($sw) / $size); |
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$dimension = (int) (($tltrCentersDimension + $tlblCentersDimension) / 2 + 7); |
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switch ($dimension % 4) { |
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case 0: |
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$dimension++; |
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break; |
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// 1? do nothing |
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case 2: |
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$dimension--; |
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break; |
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case 3: |
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throw new QRCodeDetectorException('estimated dimension: ' . $dimension); |
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} |
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if ($dimension % 4 !== 1) { |
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throw new QRCodeDetectorException('dimension mod 4 is not 1'); |
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} |
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return $dimension; |
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} |
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/** |
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* Attempts to locate an alignment pattern in a limited region of the image, which is |
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* guessed to contain it. |
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* |
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* @param float $overallEstModuleSize estimated module size so far |
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* @param int $estAlignmentX x coordinate of center of area probably containing alignment pattern |
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* @param int $estAlignmentY y coordinate of above |
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* @param float $allowanceFactor number of pixels in all directions to search from the center |
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* |
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* @return \chillerlan\QRCode\Detector\AlignmentPattern|null if found, or null otherwise |
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*/ |
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private function findAlignmentInRegion(float $overallEstModuleSize, int $estAlignmentX, int $estAlignmentY, float $allowanceFactor) : ?AlignmentPattern |
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{ |
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// Look for an alignment pattern (3 modules in size) around where it should be |
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$dimension = $this->matrix->getSize(); |
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$allowance = (int) ($allowanceFactor * $overallEstModuleSize); |
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$alignmentAreaLeftX = max(0, $estAlignmentX - $allowance); |
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$alignmentAreaRightX = min($dimension - 1, $estAlignmentX + $allowance); |
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if ($alignmentAreaRightX - $alignmentAreaLeftX < $overallEstModuleSize * 3) { |
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return null; |
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} |
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$alignmentAreaTopY = max(0, $estAlignmentY - $allowance); |
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$alignmentAreaBottomY = min($dimension - 1, $estAlignmentY + $allowance); |
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if ($alignmentAreaBottomY - $alignmentAreaTopY < $overallEstModuleSize * 3) { |
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return null; |
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} |
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return (new AlignmentPatternFinder($this->matrix, $overallEstModuleSize))->find($alignmentAreaLeftX, $alignmentAreaTopY, $alignmentAreaRightX - $alignmentAreaLeftX, $alignmentAreaBottomY - $alignmentAreaTopY); |
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} |
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/** |
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* |
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*/ |
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private function createTransform(FinderPattern $nw, FinderPattern $ne, FinderPattern $sw, int $size, ?AlignmentPattern $ap = null) : PerspectiveTransform |
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{ |
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$dimMinusThree = $size - 3.5; |
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if ($ap instanceof AlignmentPattern) { |
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$bottomRightX = $ap->getX(); |
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$bottomRightY = $ap->getY(); |
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$sourceBottomRightX = $dimMinusThree - 3.0; |
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$sourceBottomRightY = $sourceBottomRightX; |
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} else { |
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// Don't have an alignment pattern, just make up the bottom-right point |
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$bottomRightX = $ne->getX() - $nw->getX() + $sw->getX(); |
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$bottomRightY = $ne->getY() - $nw->getY() + $sw->getY(); |
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$sourceBottomRightX = $dimMinusThree; |
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$sourceBottomRightY = $dimMinusThree; |
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} |
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return (new PerspectiveTransform())->quadrilateralToQuadrilateral(3.5, 3.5, $dimMinusThree, 3.5, $sourceBottomRightX, $sourceBottomRightY, 3.5, $dimMinusThree, $nw->getX(), $nw->getY(), $ne->getX(), $ne->getY(), $bottomRightX, $bottomRightY, $sw->getX(), $sw->getY()); |
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} |
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} |
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|
