<?php
/**
* Class MaskPattern
*
* @created 19.01.2021
* @author ZXing Authors
* @author Smiley <smiley@chillerlan.net>
* @copyright 2021 Smiley
* @license Apache-2.0
*/
namespace chillerlan\QRCode\Common;
use chillerlan\QRCode\Data\QRData;
use chillerlan\QRCode\QRCodeException;
use Closure;
use function abs, array_search, count, min;
/**
* ISO/IEC 18004:2000 Section 8.8.1
* ISO/IEC 18004:2000 Section 8.8.2 - Evaluation of masking results
*
* @see http://www.thonky.com/qr-code-tutorial/data-masking
* @see https://github.com/zxing/zxing/blob/e9e2bd280bcaeabd59d0f955798384fe6c018a6c/core/src/main/java/com/google/zxing/qrcode/encoder/MaskUtil.java
*/
final class MaskPattern{
/**
* @see \chillerlan\QRCode\QROptionsTrait::$maskPattern
*
* @var int
*/
public const AUTO = -1;
public const PATTERN_000 = 0b000;
public const PATTERN_001 = 0b001;
public const PATTERN_010 = 0b010;
public const PATTERN_011 = 0b011;
public const PATTERN_100 = 0b100;
public const PATTERN_101 = 0b101;
public const PATTERN_110 = 0b110;
public const PATTERN_111 = 0b111;
/**
* @var int[]
*/
public const PATTERNS = [
self::PATTERN_000,
self::PATTERN_001,
self::PATTERN_010,
self::PATTERN_011,
self::PATTERN_100,
self::PATTERN_101,
self::PATTERN_110,
self::PATTERN_111,
];
/**
* The current mask pattern value (0-7)
*/
private int $maskPattern;
/**
* MaskPattern constructor.
*
* @throws \chillerlan\QRCode\QRCodeException
*/
public function __construct(int $maskPattern){
if((0b111 & $maskPattern) !== $maskPattern){
throw new QRCodeException('invalid mask pattern');
}
$this->maskPattern = $maskPattern;
}
/**
* Returns the current mask pattern
*/
public function getPattern():int{
return $this->maskPattern;
}
/**
* Returns a closure that applies the mask for the chosen mask pattern.
*
* Encapsulates data masks for the data bits in a QR code, per ISO 18004:2006 6.8. Implementations
* of this class can un-mask a raw BitMatrix. For simplicity, they will unmask the entire BitMatrix,
* including areas used for finder patterns, timing patterns, etc. These areas should be unused
* after the point they are unmasked anyway.
*
* 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.
*
* @see https://www.thonky.com/qr-code-tutorial/mask-patterns
* @see https://github.com/zxing/zxing/blob/e9e2bd280bcaeabd59d0f955798384fe6c018a6c/core/src/main/java/com/google/zxing/qrcode/decoder/DataMask.java#L32-L117
*/
public function getMask():Closure{
// $x = column (width), $y = row (height)
return [
self::PATTERN_000 => fn(int $x, int $y):bool => (($x + $y) % 2) === 0,
self::PATTERN_001 => fn(int $x, int $y):bool => ($y % 2) === 0,
self::PATTERN_010 => fn(int $x, int $y):bool => ($x % 3) === 0,
self::PATTERN_011 => fn(int $x, int $y):bool => (($x + $y) % 3) === 0,
self::PATTERN_100 => fn(int $x, int $y):bool => (((int)($y / 2) + (int)($x / 3)) % 2) === 0,
self::PATTERN_101 => fn(int $x, int $y):bool => (($x * $y) % 6) === 0, // ((($x * $y) % 2) + (($x * $y) % 3)) === 0,
self::PATTERN_110 => fn(int $x, int $y):bool => (($x * $y) % 6) < 3, // (((($x * $y) % 2) + (($x * $y) % 3)) % 2) === 0,
self::PATTERN_111 => fn(int $x, int $y):bool => (($x + $y + (($x * $y) % 3)) % 2) === 0, // (((($x * $y) % 3) + (($x + $y) % 2)) % 2) === 0,
][$this->maskPattern];
}
/**
* Evaluates the matrix of the given data interface and returns a new mask pattern instance for the best result
*/
public static function getBestPattern(QRData $dataInterface):self{
$penalties = [];
foreach(self::PATTERNS as $pattern){
$matrix = $dataInterface->writeMatrix(new self($pattern))->matrix(true);
$penalty = 0;
for($level = 1; $level <= 4; $level++){
$penalty += self::{'testRule'.$level}($matrix, count($matrix), count($matrix[0]));
}
$penalties[$pattern] = (int)$penalty;
}
return new self(array_search(min($penalties), $penalties, true));
}
/**
* Apply mask penalty rule 1 and return the penalty. Find repetitive cells with the same color and
* give penalty to them. Example: 00000 or 11111.
*/
public static function testRule1(array $matrix, int $height, int $width):int{
return (self::applyRule1($matrix, $height, $width, true) + self::applyRule1($matrix, $height, $width, false));
}
/**
*
*/
private static function applyRule1(array $matrix, int $height, int $width, bool $isHorizontal):int{
$penalty = 0;
$yLimit = ($isHorizontal) ? $height : $width;
$xLimit = ($isHorizontal) ? $width : $height;
for($y = 0; $y < $yLimit; $y++){
$numSameBitCells = 0;
$prevBit = null;
for($x = 0; $x < $xLimit; $x++){
$bit = ($isHorizontal) ? $matrix[$y][$x] : $matrix[$x][$y];
if($bit === $prevBit){
$numSameBitCells++;
}
else{
if($numSameBitCells >= 5){
$penalty += (3 + ($numSameBitCells - 5));
}
$numSameBitCells = 1; // Include the cell itself.
$prevBit = $bit;
}
}
if($numSameBitCells >= 5){
$penalty += (3 + ($numSameBitCells - 5));
}
}
return $penalty;
}
/**
* Apply mask penalty rule 2 and return the penalty. Find 2x2 blocks with the same color and give
* penalty to them. This is actually equivalent to the spec's rule, which is to find MxN blocks and give a
* penalty proportional to (M-1)x(N-1), because this is the number of 2x2 blocks inside such a block.
*/
public static function testRule2(array $matrix, int $height, int $width):int{
$penalty = 0;
foreach($matrix as $y => $row){
if($y > ($height - 2)){
break;
}
foreach($row as $x => $val){
if($x > ($width - 2)){
break;
}
if(
$val === $row[($x + 1)]
&& $val === $matrix[($y + 1)][$x]
&& $val === $matrix[($y + 1)][($x + 1)]
){
$penalty++;
}
}
}
return (3 * $penalty);
}
/**
* Apply mask penalty rule 3 and return the penalty. Find consecutive runs of 1:1:3:1:1:4
* starting with black, or 4:1:1:3:1:1 starting with white, and give penalty to them. If we
* find patterns like 000010111010000, we give penalty once.
*/
public static function testRule3(array $matrix, int $height, int $width):int{
$penalties = 0;
foreach($matrix as $y => $row){
foreach($row as $x => $val){
if(
($x + 6) < $width
&& $val
&& !$row[($x + 1)]
&& $row[($x + 2)]
&& $row[($x + 3)]
&& $row[($x + 4)]
&& !$row[($x + 5)]
&& $row[($x + 6)]
&& (
self::isWhiteHorizontal($row, $width, ($x - 4), $x)
|| self::isWhiteHorizontal($row, $width, ($x + 7), ($x + 11))
)
){
$penalties++;
}
if(
($y + 6) < $height
&& $val
&& !$matrix[($y + 1)][$x]
&& $matrix[($y + 2)][$x]
&& $matrix[($y + 3)][$x]
&& $matrix[($y + 4)][$x]
&& !$matrix[($y + 5)][$x]
&& $matrix[($y + 6)][$x]
&& (
self::isWhiteVertical($matrix, $height, $x, ($y - 4), $y)
|| self::isWhiteVertical($matrix, $height, $x, ($y + 7), ($y + 11))
)
){
$penalties++;
}
}
}
return ($penalties * 40);
}
/**
*
*/
private static function isWhiteHorizontal(array $row, int $width, int $from, int $to):bool{
if($from < 0 || $width < $to){
return false;
}
for($x = $from; $x < $to; $x++){
if($row[$x]){
return false;
}
}
return true;
}
/**
*
*/
private static function isWhiteVertical(array $matrix, int $height, int $x, int $from, int $to):bool{
if($from < 0 || $height < $to){
return false;
}
for($y = $from; $y < $to; $y++){
if($matrix[$y][$x]){
return false;
}
}
return true;
}
/**
* Apply mask penalty rule 4 and return the penalty. Calculate the ratio of dark cells and give
* penalty if the ratio is far from 50%. It gives 10 penalty for 5% distance.
*/
public static function testRule4(array $matrix, int $height, int $width):int{
$darkCells = 0;
$totalCells = ($height * $width);
foreach($matrix as $row){
foreach($row as $val){
if($val){
$darkCells++;
}
}
}
return ((int)(abs($darkCells * 2 - $totalCells) * 10 / $totalCells) * 10);
}
}