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<?php
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// $Id: color.algorithms.inc,v 1.2.2.2 2008/08/20 16:45:41 skiquel Exp $
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/**
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* @file
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* Color manipulation functions
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*/
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/**
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* Convert a hex triplet into a GD color.
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*
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* @param $img
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* GD Image
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* @param $hex
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* String of hex
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* @return
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* GD Color
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*/
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function _color_gd($img, $hex) {
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$c = array_merge(array($img), _color_unpack($hex));
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return call_user_func_array('imagecolorallocate', $c);
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}
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/**
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* Blend two hex colors and return the GD color.
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*
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* @param $img
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* GD Image
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* @param $hex1
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* String of first value.
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* @param $hex2
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* String of second value.
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* @param $alpha
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* Integer of alpha
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* @return
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* GD Color
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*/
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function _color_blend($img, $hex1, $hex2, $alpha) {
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$in1 = _color_unpack($hex1);
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$in2 = _color_unpack($hex2);
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$out = array($img);
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for ($i = 0; $i < 3; ++$i) {
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$out[] = $in1[$i] + ($in2[$i] - $in1[$i]) * $alpha;
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}
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return call_user_func_array('imagecolorallocate', $out);
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}
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/**
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* Convert a hex color into an RGB triplet.
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*
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* @param $hex
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* String of hex value
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* @param $normalize
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* Normalize RGB
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* @return
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* Array of RGB triplet
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*/
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function _color_unpack($hex, $normalize = FALSE) {
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if (strlen($hex) == 4) {
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$hex = $hex[1] . $hex[1] . $hex[2] . $hex[2] . $hex[3] . $hex[3];
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}
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$c = hexdec($hex);
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for ($i = 16; $i >= 0; $i -= 8) {
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$out[] = (($c >> $i) & 0xFF) / ($normalize ? 255 : 1);
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}
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return $out;
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}
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/**
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* Convert an RGB triplet to a hex color.
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*
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* @param $rgb
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* Array of RGB integers
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* @param $normalize
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* Boolean
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* @return
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* String of full hex. (i.e. #ffffff)
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*/
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function _color_pack($rgb, $normalize = FALSE) {
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$out = 0;
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foreach ($rgb as $k => $v) {
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$out |= (($v * ($normalize ? 255 : 1)) << (16 - $k * 8));
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}
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return '#'. str_pad(dechex($out), 6, 0, STR_PAD_LEFT);
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}
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/**
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* Convert a HSL triplet into RGB
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*
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* @param $hsl
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* Array of 3 integers, 0-1. HSL Value.
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* @return
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* Array, the RGB value
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*/
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function _color_hsl2rgb($hsl) {
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$h = $hsl[0];
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$s = $hsl[1];
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$l = $hsl[2];
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$m2 = ($l <= 0.5) ? $l * ($s + 1) : $l + $s - $l*$s;
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$m1 = $l * 2 - $m2;
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return array(
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_color_hue2rgb($m1, $m2, $h + 0.33333),
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_color_hue2rgb($m1, $m2, $h),
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_color_hue2rgb($m1, $m2, $h - 0.33333),
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);
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}
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/**
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* Helper function for _color_hsl2rgb().
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*
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* @param $m1
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* Decimal, 0-1
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* @param $m2
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* Decimal, 0-1
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* @param @h
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* Decimal, 0-1
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* @return
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* Decimal, RGB value
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*/
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function _color_hue2rgb($m1, $m2, $h) {
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$h = ($h < 0) ? $h + 1 : (($h > 1) ? $h - 1 : $h);
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if ($h * 6 < 1) return $m1 + ($m2 - $m1) * $h * 6;
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if ($h * 2 < 1) return $m2;
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if ($h * 3 < 2) return $m1 + ($m2 - $m1) * (0.66666 - $h) * 6;
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return $m1;
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}
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/**
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* Convert an RGB triplet to HSL.
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*
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* @param $rgb
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* Array of RGB integer values
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* @return
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* Array of HSL integer values
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*/
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function _color_rgb2hsl($rgb) {
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$r = $rgb[0];
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$g = $rgb[1];
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$b = $rgb[2];
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$min = min($r, min($g, $b));
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$max = max($r, max($g, $b));
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$delta = $max - $min;
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$l = ($min + $max) / 2;
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$s = 0;
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if ($l > 0 && $l < 1) {
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$s = $delta / ($l < 0.5 ? (2 * $l) : (2 - 2 * $l));
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}
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$h = 0;
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if ($delta > 0) {
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if ($max == $r && $max != $g) $h += ($g - $b) / $delta;
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if ($max == $g && $max != $b) $h += (2 + ($b - $r) / $delta);
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if ($max == $b && $max != $r) $h += (4 + ($r - $g) / $delta);
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$h /= 6;
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}
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return array($h, $s, $l);
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}
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