Note that the diagram in section 6.8.1 is misleading since it indicates that i is column position * and j is row position. In fact, as the text says, i is row position and j is column position.
* * @author Sean Owen */ abstract class DataMask { /** * See ISO 18004:2006 6.8.1 */ private static $DATA_MASKS = array(); static function Init() { self::$DATA_MASKS = array( new DataMask000(), new DataMask001(), new DataMask010(), new DataMask011(), new DataMask100(), new DataMask101(), new DataMask110(), new DataMask111(), ); } function __construct() { } /** *Implementations of this method reverse the data masking process applied to a QR Code and * make its bits ready to read.
* * @param bits representation of QR Code bits * @param dimension dimension of QR Code, represented by bits, being unmasked */ final function unmaskBitMatrix($bits, $dimension) { for ($i = 0; $i < $dimension; $i++) { for ($j = 0; $j < $dimension; $j++) { if ($this->isMasked($i, $j)) { $bits->flip($j, $i); } } } } abstract function isMasked($i, $j); /** * @param reference a value between 0 and 7 indicating one of the eight possible * data mask patterns a QR Code may use * @return DataMask encapsulating the data mask pattern */ static function forReference($reference) { if ($reference < 0 || $reference > 7) { throw new \InvalidArgumentException(); } return self::$DATA_MASKS[$reference]; } } DataMask::Init(); /** * 000: mask bits for which (x + y) mod 2 == 0 */ final class DataMask000 extends DataMask { // @Override function isMasked($i, $j) { return (($i + $j) & 0x01) == 0; } } /** * 001: mask bits for which x mod 2 == 0 */ final class DataMask001 extends DataMask { //@Override function isMasked($i, $j) { return ($i & 0x01) == 0; } } /** * 010: mask bits for which y mod 3 == 0 */ final class DataMask010 extends DataMask { //@Override function isMasked($i, $j) { return $j % 3 == 0; } } /** * 011: mask bits for which (x + y) mod 3 == 0 */ final class DataMask011 extends DataMask { //@Override function isMasked($i, $j) { return ($i + $j) % 3 == 0; } } /** * 100: mask bits for which (x/2 + y/3) mod 2 == 0 */ final class DataMask100 extends DataMask { //@Override function isMasked($i, $j) { return intval((intval($i / 2) + intval($j /3)) & 0x01) == 0; } } /** * 101: mask bits for which xy mod 2 + xy mod 3 == 0 */ final class DataMask101 extends DataMask { //@Override function isMasked($i, $j) { $temp = $i * $j; return ($temp & 0x01) + ($temp % 3) == 0; } } /** * 110: mask bits for which (xy mod 2 + xy mod 3) mod 2 == 0 */ final class DataMask110 extends DataMask { //@Override function isMasked($i, $j) { $temp = $i * $j; return ((($temp & 0x01) + ($temp % 3)) & 0x01) == 0; } } /** * 111: mask bits for which ((x+y)mod 2 + xy mod 3) mod 2 == 0 */ final class DataMask111 extends DataMask { //@Override function isMasked($i, $j) { return (((($i + $j) & 0x01) + (($i * $j) % 3)) & 0x01) == 0; } }