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<?php
/* Icinga Web 2 | (c) 2014 Icinga Development Team | GPLv2+ */
namespace Icinga\Util;
/**
* Provide functions to change and convert colors.
*/
class Color
{
/**
* Convert a given color string to an rgb-array containing
* each color as a decimal value.
*
* @param $color The color-string #RRGGBB
*
* @return array The converted rgb-array.
*/
public static function rgbAsArray($color)
{
if (substr($color, 0, 1) !== '#') {
$color = '#' . $color;
}
if (strlen($color) !== 7) {
return;
}
$r = (float)intval(substr($color, 1, 2), 16);
$g = (float)intval(substr($color, 3, 2), 16);
$b = (float)intval(substr($color, 5, 2), 16);
return array($r, $g, $b);
}
/**
* Convert a rgb array to a color-string
*
* @param array $rgb The rgb-array
*
* @return string The color string #RRGGBB
*/
public static function arrayToRgb(array $rgb)
{
$r = (string)dechex($rgb[0]);
$g = (string)dechex($rgb[1]);
$b = (string)dechex($rgb[2]);
return '#'
. (strlen($r) > 1 ? $r : '0' . $r)
. (strlen($g) > 1 ? $g : '0' . $g)
. (strlen($b) > 1 ? $b : '0' . $b);
}
/**
* Change the saturation for a given color.
*
* @param $color string The color to change
* @param $change float The change.
* 0.0 creates a black-and-white image.
* 0.5 reduces the color saturation by half.
* 1.0 causes no change.
* 2.0 doubles the color saturation.
* @return string
*/
public static function changeSaturation($color, $change)
{
return self::arrayToRgb(self::changeRgbSaturation(self::rgbAsArray($color), $change));
}
/**
* Change the brightness for a given color
*
* @param $color string The color to change
* @param $change float The change in percent
*
* @return string
*/
public static function changeBrightness($color, $change)
{
return self::arrayToRgb(self::changeRgbBrightness(self::rgbAsArray($color), $change));
}
/**
* @param $rgb array The rgb-array to change
* @param $change float The factor
*
* @return array The updated rgb-array
*/
private static function changeRgbSaturation(array $rgb, $change)
{
$pr = 0.499; // 0.299
$pg = 0.387; // 0.587
$pb = 0.114; // 0.114
$r = $rgb[0];
$g = $rgb[1];
$b = $rgb[2];
$p = sqrt(
$r * $r * $pr +
$g * $g * $pg +
$b * $b * $pb
);
$rgb[0] = (int)($p + ($r - $p) * $change);
$rgb[1] = (int)($p + ($g - $p) * $change);
$rgb[2] = (int)($p + ($b - $p) * $change);
return $rgb;
}
/**
* @param $rgb array The rgb-array to change
* @param $change float The factor
*
* @return array The updated rgb-array
*/
private static function changeRgbBrightness(array $rgb, $change)
{
$red = $rgb[0] + ($rgb[0] * $change);
$green = $rgb[1] + ($rgb[1] * $change);
$blue = $rgb[2] + ($rgb[2] * $change);
$rgb[0] = $red < 255 ? (int) $red : 255;
$rgb[1] = $green < 255 ? (int) $green : 255;
$rgb[2] = $blue < 255 ? (int) $blue : 255;
return $rgb;
}
}
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