Detects a QR Code in an image.
* * @return {@link DetectorResult} encapsulating results of detecting a QR Code * @throws NotFoundException if QR Code cannot be found * @throws FormatException if a QR Code cannot be decoded */ /** *Detects a QR Code in an image.
* * @param hints optional hints to detector * @return {@link DetectorResult} encapsulating results of detecting a QR Code * @throws NotFoundException if QR Code cannot be found * @throws FormatException if a QR Code cannot be decoded */ public final function detect($hints=null){/*MapComputes the dimension (number of modules on a size) of the QR Code based on the position * of the finder patterns and estimated module size.
*/ private static function computeDimension($topLeft, $topRight, $bottomLeft, $moduleSize) { $tltrCentersDimension = MathUtils::round(ResultPoint::distance($topLeft, $topRight) / $moduleSize); $tlblCentersDimension = MathUtils::round(ResultPoint::distance($topLeft, $bottomLeft) / $moduleSize); $dimension = (($tltrCentersDimension + $tlblCentersDimension) / 2) + 7; switch ($dimension & 0x03) { // mod 4 case 0: $dimension++; break; // 1? do nothing case 2: $dimension--; break; case 3: throw NotFoundException::getNotFoundInstance(); } return $dimension; } /** *Computes an average estimated module size based on estimated derived from the positions * of the three finder patterns.
* * @param topLeft detected top-left finder pattern center * @param topRight detected top-right finder pattern center * @param bottomLeft detected bottom-left finder pattern center * @return estimated module size */ protected final function calculateModuleSize($topLeft, $topRight, $bottomLeft) { // Take the average return ($this->calculateModuleSizeOneWay($topLeft, $topRight) + $this->calculateModuleSizeOneWay($topLeft, $bottomLeft)) / 2.0; } /** *Estimates module size based on two finder patterns -- it uses * {@link #sizeOfBlackWhiteBlackRunBothWays(int, int, int, int)} to figure the * width of each, measuring along the axis between their centers.
*/ private function calculateModuleSizeOneWay($pattern, $otherPattern) { $moduleSizeEst1 = $this->sizeOfBlackWhiteBlackRunBothWays($pattern->getX(), (int) $pattern->getY(), (int) $otherPattern->getX(), (int) $otherPattern->getY()); $moduleSizeEst2 = $this->sizeOfBlackWhiteBlackRunBothWays((int) $otherPattern->getX(), (int) $otherPattern->getY(), (int) $pattern->getX(), (int) $pattern->getY()); if (is_nan($moduleSizeEst1)) { return $moduleSizeEst2 / 7.0; } if (is_nan($moduleSizeEst2)) { return $moduleSizeEst1 / 7.0; } // Average them, and divide by 7 since we've counted the width of 3 black modules, // and 1 white and 1 black module on either side. Ergo, divide sum by 14. return ($moduleSizeEst1 + $moduleSizeEst2) / 14.0; } /** * See {@link #sizeOfBlackWhiteBlackRun(int, int, int, int)}; computes the total width of * a finder pattern by looking for a black-white-black run from the center in the direction * of another po$(another finder pattern center), and in the opposite direction too. */ private function sizeOfBlackWhiteBlackRunBothWays($fromX, $fromY, $toX, $toY) { $result = $this->sizeOfBlackWhiteBlackRun($fromX, $fromY, $toX, $toY); // Now count other way -- don't run off image though of course $scale = 1.0; $otherToX = $fromX - ($toX - $fromX); if ($otherToX < 0) { $scale = (float) $fromX / (float) ($fromX - $otherToX); $otherToX = 0; } else if ($otherToX >= $this->image->getWidth()) { $scale = (float) ($this->image->getWidth() - 1 - $fromX) / (float) ($otherToX - $fromX); $otherToX = $this->image->getWidth() - 1; } $otherToY = (int) ($fromY - ($toY - $fromY) * $scale); $scale = 1.0; if ($otherToY < 0) { $scale = (float) $fromY / (float) ($fromY - $otherToY); $otherToY = 0; } else if ($otherToY >= $this->image->getHeight()) { $scale = (float) ($this->image->getHeight() - 1 - $fromY) / (float) ($otherToY - $fromY); $otherToY = $this->image->getHeight() - 1; } $otherToX = (int) ($fromX + ($otherToX - $fromX) * $scale); $result += $this->sizeOfBlackWhiteBlackRun($fromX, $fromY, $otherToX, $otherToY); // Middle pixel is double-counted this way; subtract 1 return $result - 1.0; } /** *This method traces a line from a po$in the image, in the direction towards another point. * It begins in a black region, and keeps going until it finds white, then black, then white again. * It reports the distance from the start to this point.
* *This is used when figuring out how wide a finder pattern is, when the finder pattern * may be skewed or rotated.
*/ private function sizeOfBlackWhiteBlackRun($fromX, $fromY, $toX, $toY) { // Mild variant of Bresenham's algorithm; // see http://en.wikipedia.org/wiki/Bresenham's_line_algorithm $steep = abs($toY - $fromY) > abs($toX - $fromX); if ($steep) { $temp = $fromX; $fromX = $fromY; $fromY = $temp; $temp = $toX; $toX = $toY; $toY = $temp; } $dx = abs($toX - $fromX); $dy = abs($toY - $fromY); $error = -$dx / 2; $xstep = $fromX < $toX ? 1 : -1; $ystep = $fromY < $toY ? 1 : -1; // In black pixels, looking for white, first or second time. $state = 0; // Loop up until x == toX, but not beyond $xLimit = $toX + $xstep; for ($x = $fromX, $y = $fromY; $x != $xLimit; $x += $xstep) { $realX = $steep ? $y : $x; $realY = $steep ? $x : $y; // Does current pixel mean we have moved white to black or vice versa? // Scanning black in state 0,2 and white in state 1, so if we find the wrong // color, advance to next state or end if we are in state 2 already if (($state == 1) == $this->image->get($realX, $realY)) { if ($state == 2) { return MathUtils::distance($x, $y, $fromX, $fromY); } $state++; } $error += $dy; if ($error > 0) { if ($y == $toY) { break; } $y += $ystep; $error -= $dx; } } // Found black-white-black; give the benefit of the doubt that the next pixel outside the image // is "white" so this last po$at (toX+xStep,toY) is the right ending. This is really a // small approximation; (toX+xStep,toY+yStep) might be really correct. Ignore this. if ($state == 2) { return MathUtils::distance($toX + $xstep, $toY, $fromX, $fromY); } // else we didn't find even black-white-black; no estimate is really possible return NAN; } /** *Attempts to locate an alignment pattern in a limited region of the image, which is * guessed to contain it. This method uses {@link AlignmentPattern}.
* * @param overallEstModuleSize estimated module size so far * @param estAlignmentX x coordinate of center of area probably containing alignment pattern * @param estAlignmentY y coordinate of above * @param allowanceFactor number of pixels in all directions to search from the center * @return {@link AlignmentPattern} if found, or null otherwise * @throws NotFoundException if an unexpected error occurs during detection */ protected final function findAlignmentInRegion($overallEstModuleSize, $estAlignmentX, $estAlignmentY, $allowanceFactor) { // Look for an alignment pattern (3 modules in size) around where it // should be $allowance = (int) ($allowanceFactor * $overallEstModuleSize); $alignmentAreaLeftX = max(0, $estAlignmentX - $allowance); $alignmentAreaRightX = min($this->image->getWidth() - 1, $estAlignmentX + $allowance); if ($alignmentAreaRightX - $alignmentAreaLeftX < $overallEstModuleSize * 3) { throw NotFoundException::getNotFoundInstance(); } $alignmentAreaTopY = max(0, $estAlignmentY - $allowance); $alignmentAreaBottomY = min($this->image->getHeight() - 1, $estAlignmentY + $allowance); if ($alignmentAreaBottomY - $alignmentAreaTopY < $overallEstModuleSize * 3) { throw NotFoundException::getNotFoundInstance(); } $alignmentFinder = new AlignmentPatternFinder( $this->image, $alignmentAreaLeftX, $alignmentAreaTopY, $alignmentAreaRightX - $alignmentAreaLeftX, $alignmentAreaBottomY - $alignmentAreaTopY, $overallEstModuleSize, $this->resultPointCallback); return $alignmentFinder->find(); } }