121 lines
3.5 KiB
PHP
121 lines
3.5 KiB
PHP
<?php
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/* Icinga Web 2 | (c) 2013-2015 Icinga Development Team | http://www.gnu.org/licenses/gpl-2.0.txt */
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namespace Icinga\Util;
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/**
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* Provide functions to change and convert colors.
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*/
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class Color {
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/**
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* Convert a given color string to an rgb-array containing
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* each color as a decimal value.
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*
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* @param $color The color-string #RRGGBB
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*
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* @return array The converted rgb-array.
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*/
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public static function rgbAsArray($color)
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{
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if (substr($color, 0, 1) !== '#') {
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$color = '#' . $color;
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}
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if (strlen($color) !== 7) {
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return;
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}
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$r = (float)intval(substr($color, 1, 2), 16);
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$g = (float)intval(substr($color, 3, 2), 16);
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$b = (float)intval(substr($color, 5, 2), 16);
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return array($r, $g, $b);
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}
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/**
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* Convert a rgb array to a color-string
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*
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* @param array $rgb The rgb-array
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*
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* @return string The color string #RRGGBB
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*/
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public static function arrayToRgb(array $rgb)
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{
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$r = (string)dechex($rgb[0]);
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$g = (string)dechex($rgb[1]);
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$b = (string)dechex($rgb[2]);
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return '#'
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. (strlen($r) > 1 ? $r : '0' . $r)
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. (strlen($g) > 1 ? $g : '0' . $g)
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. (strlen($b) > 1 ? $b : '0' . $b);
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}
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/**
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* Change the saturation for a given color.
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*
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* @param $color string The color to change
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* @param $change float The change.
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* 0.0 creates a black-and-white image.
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* 0.5 reduces the color saturation by half.
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* 1.0 causes no change.
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* 2.0 doubles the color saturation.
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* @return string
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*/
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public static function changeSaturation($color, $change)
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{
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return self::arrayToRgb(self::changeRgbSaturation(self::rgbAsArray($color), $change));
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}
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/**
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* Change the brightness for a given color
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*
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* @param $color string The color to change
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* @param $change float The change in percent
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*
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* @return string
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*/
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public static function changeBrightness($color, $change)
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{
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return self::arrayToRgb(self::changeRgbBrightness(self::rgbAsArray($color), $change));
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}
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/**
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* @param $rgb array The rgb-array to change
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* @param $change float The factor
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*
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* @return array The updated rgb-array
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*/
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private static function changeRgbSaturation(array $rgb, $change)
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{
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$pr = 0.499; // 0.299
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$pg = 0.387; // 0.587
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$pb = 0.114; // 0.114
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$r = $rgb[0];
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$g = $rgb[1];
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$b = $rgb[2];
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$p = sqrt(
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$r * $r * $pr +
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$g * $g * $pg +
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$b * $b * $pb
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);
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$rgb[0] = (int)($p + ($r - $p) * $change);
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$rgb[1] = (int)($p + ($g - $p) * $change);
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$rgb[2] = (int)($p + ($b - $p) * $change);
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return $rgb;
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}
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/**
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* @param $rgb array The rgb-array to change
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* @param $change float The factor
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*
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* @return array The updated rgb-array
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*/
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private static function changeRgbBrightness(array $rgb, $change)
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{
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$red = $rgb[0] + ($rgb[0] * $change);
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$green = $rgb[1] + ($rgb[1] * $change);
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$blue = $rgb[2] + ($rgb[2] * $change);
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$rgb[0] = $red < 255 ? (int) $red : 255;
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$rgb[1] = $green < 255 ? (int) $green : 255;
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$rgb[2] = $blue < 255 ? (int) $blue : 255;
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return $rgb;
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}
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}
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