From: Alexander Ebert <ebert@woltlab.com>
Date: Sun, 25 Sep 2016 10:30:15 +0000 (+0200)
Subject: Approximate color using a Delta E (CIE 1994) diff
X-Git-Tag: 3.0.0_Beta_2~151
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=701517480b29d182649664f166ffc4728c99408a;p=GitHub%2FWoltLab%2FWCF.git

Approximate color using a Delta E (CIE 1994) diff
---

diff --git a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeWoltlabColor.class.php b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeWoltlabColor.class.php
new file mode 100644
index 0000000000..f0f0b640d7
--- /dev/null
+++ b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeWoltlabColor.class.php
@@ -0,0 +1,207 @@
+<?php
+namespace wcf\system\html\input\node;
+use wcf\data\bbcode\BBCodeCache;
+use wcf\system\bbcode\BBCodeHandler;
+use wcf\system\html\metacode\converter\IMetacodeConverter;
+use wcf\system\html\node\AbstractHtmlNodeProcessor;
+use wcf\util\DOMUtil;
+use wcf\util\StringUtil;
+
+/**
+ * Processes `<woltlab-color>` to check for valid color arguments.
+ *
+ * @author      Alexander Ebert
+ * @copyright   2001-2016 WoltLab GmbH
+ * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @package     WoltLabSuite\Core\System\Html\Input\Node
+ * @since       3.0
+ */
+class HtmlInputNodeWoltlabColor extends AbstractHtmlInputNode {
+	/**
+	 * @inheritDoc
+	 */
+	protected $tagName = 'woltlab-color';
+	
+	public static $validColors = [
+		'000000', '000080', '0000CD', '0000FF', '006400', '008000', '008080', '00FF00',
+		'00FFFF', '2F4F4F', '40E0D0', '4B0082', '696969', '800000', '800080', '808080',
+		'8B4513', 'A52A2A', 'A9A9A9', 'ADD8E6', 'AFEEEE', 'B22222', 'D3D3D3', 'DAA520',
+		'DDA0DD', 'E6E6FA', 'EE82EE', 'F0F8FF', 'F0FFF0', 'F0FFFF', 'FAEBD7', 'FF0000',
+		'FF8C00', 'FFA07A', 'FFA500', 'FFD700', 'FFF0F5', 'FFFF00', 'FFFFE0', 'FFFFFF'
+	];
+	
+	protected static $colorsToLab = [];
+	
+	/**
+	 * @inheritDoc
+	 */
+	public function isAllowed(AbstractHtmlNodeProcessor $htmlNodeProcessor) {
+		if (BBCodeHandler::getInstance()->isAvailableBBCode('color')) {
+			return [];
+		}
+		
+		if (!$htmlNodeProcessor->getDocument()->getElementsByTagName('woltlab-color')->length) {
+			return [];
+		}
+		
+		return ['color'];
+	}
+	
+	/**
+	 * @inheritDoc
+	 */
+	public function process(array $elements, AbstractHtmlNodeProcessor $htmlNodeProcessor) {
+		/** @var \DOMElement $element */
+		foreach ($elements as $element) {
+			if (preg_match('~\bwoltlab-color-([a-z0-9]{6})\b~i', $element->getAttribute('class'), $matches)) {
+				$color = strtoupper($matches[1]);
+				if (!in_array($color, self::$validColors)) {
+					$color = $this->getClosestColor($color);
+				}
+				
+				$element->setAttribute('class', 'woltlab-color-'.$color);
+			}
+			else {
+				DOMUtil::removeNode($element, true);
+			}
+		}
+	}
+	
+	protected function getClosestColor($hex) {
+		if (empty(self::$colorsToLab)) {
+			// build static lookup table
+			foreach (self::$validColors as $color) {
+				self::$colorsToLab[$color] = $this->hexToLab($color);
+			}
+		}
+		
+		$lab1 = $this->hexToLab($hex);
+		
+		$diff = 0;
+		$newColor = '';
+		
+		foreach (self::$colorsToLab as $color => $lab2) {
+			$newDiff = $this->deltaE_cie1994($lab1, $lab2);
+			
+			if ($newColor === '' || $diff > $newDiff) {
+				$diff = $newDiff;
+				$newColor = $color;
+			}
+		}
+		
+		return $newColor;
+	}
+	
+	protected function hexToLab($hex) {
+		return $this->xyzToLab(
+			$this->rgbToXyz(
+				$this->hexToRgb($hex)
+			)
+		);
+	}
+	
+	protected function hexToRgb($hex) {
+		// [r, g, b]
+		return [
+			hexdec($hex{0}.$hex{1}),
+			hexdec($hex{2}.$hex{3}),
+			hexdec($hex{4}.$hex{5})
+		];
+	}
+	
+	protected function rgbToXyz($rgb) {
+		// convert into values between 0 and 1
+		$red = $rgb[0] / 255;
+		$green = $rgb[1] / 255;
+		$blue = $rgb[2] / 255;
+		
+		if ($red > 0.04045) {
+			$red = ($red + 0.055) / 1.055;
+			$red = pow($red, 2.4);
+		}
+		else {
+			$red = $red / 12.92;
+		}
+		
+		if ($green > 0.04045) {
+			$green = ($green + 0.055) / 1.055;
+			$green = pow($green, 2.4);
+		}
+		else {
+			$green = $green / 12.92;
+		}
+		
+		if ($blue > 0.04045) {
+			$blue = ($blue + 0.055) / 1.055;
+			$blue = pow($blue, 2.4);
+		}
+		else {
+			$blue = $blue / 12.92;
+		}
+		
+		$red *= 100;
+		$green *= 100;
+		$blue *= 100;
+		
+		// [x, y, z]
+		return [
+			$red * 0.4124 + $green * 0.3576 + $blue * 0.1805,
+			$red * 0.2126 + $green * 0.7152 + $blue * 0.0722,
+			$red * 0.0193 + $green * 0.1192 + $blue * 0.9505
+		];
+	}
+	
+	protected function xyzToLab($xyz) {
+		$x = $xyz[0] / 95.047;
+		$y = $xyz[1] / 100;
+		$z = $xyz[2] / 108.883;
+		
+		if ($x > 0.008856) {
+			$x = pow($x, 1 / 3);
+		}
+		else {
+			$x = 7.787 * $x + 16 / 116;
+		}
+		
+		if ($y > 0.008856) {
+			$y = pow($y, 1 / 3);
+		}
+		else {
+			$y = (7.787 * $y) + (16 / 116);
+		}
+		
+		if ($z > 0.008856) {
+			$z = pow($z, 1 / 3);
+		}
+		else {
+			$z = 7.787 * $z + 16 / 116;
+		}
+		
+		// [l, a, b]
+		return [
+			116 * $y - 16,
+			500 * ($x - $y),
+			200 * ($y - $z)
+		];
+	}
+	
+	protected function deltaE_cie1994($lab1, $lab2) {
+		// Delta E (CIE 1994) difference of two colors
+		// http://www.brucelindbloom.com/index.html?Eqn_DeltaE_CIE94.html
+		$c1 = sqrt($lab1[1] * $lab1[1] + $lab1[2] * $lab1[2]);
+		$c2 = sqrt($lab2[1] * $lab2[1] + $lab2[2] * $lab2[2]);
+		
+		$dc = $c1 - $c2;
+		$dl = $lab1[0] - $lab2[0];
+		$da = $lab1[1] - $lab2[1];
+		$db = $lab1[2] - $lab2[2];
+		$dh = ($da * $da) + ($db * $db) - ($dc * $dc);
+		$dh = ($dh < 0) ? 0 : sqrt($dh);
+		
+		$first = $dl;
+		$second = $dc / (1 + 0.045 * $c1);
+		$third = $dh / (1 + 0.015 * $c1);
+		
+		return sqrt($first * $first + $second * $second + $third * $third);
+	}
+}