55 lines
1.6 KiB
PHP
55 lines
1.6 KiB
PHP
<?php
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// These functions are borrowed from the colorline lib
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if ( ! function_exists( 'hex_to_rgb' ) ) {
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function hex_to_rgb( $hex ) {
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return sscanf( $hex, '%02X%02X%02X' );
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}
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}
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// RGB values: 0-255
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// LUM values: 0-1
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if ( ! function_exists( 'rgb_to_lum' ) ) {
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function rgb_to_lum( $rgb ) {
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list( $r, $g, $b ) = $rgb;
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return sqrt( 0.241 * $r * $r + 0.691 * $g * $g + 0.068 * $b * $b ) / 255;
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}
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}
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// RGB values: 0-255, 0-255, 0-255
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// HSV values: 0-360, 0-100, 0-100, 0-100
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if ( ! function_exists( 'rgb_to_hsvl' ) ) {
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function rgb_to_hsvl( $rgb ) {
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$l = rgb_to_lum( $rgb );
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list( $r, $g, $b ) = $rgb;
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$r = $r / 255;
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$g = $g / 255;
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$b = $b / 255;
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$max_rgb = max( $r, $g, $b );
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$min_rgb = min( $r, $g, $b );
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$chroma = $max_rgb - $min_rgb;
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$v = 100 * $max_rgb;
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if ( $chroma > 0 ) {
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$s = 100 * ( $chroma / $max_rgb );
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if ( $r === $min_rgb ) {
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$h = 3 - ( ( $g - $b ) / $chroma );
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} elseif ( $b === $min_rgb ) {
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$h = 1 - ( ( $r - $g ) / $chroma );
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} else { // $g === $min_rgb
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$h = 5 - ( ( $b - $r ) / $chroma );
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}
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$h = 60 * $h;
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return array( $h, $s, $v, $l );
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} else {
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return array( 0, 0, $v, $l );
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}
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}
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}
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if ( ! function_exists( 'change_color_luminescence' ) ) {
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function change_color_luminescence( $hex, $amount ) {
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$hex_without_hash = substr( $hex, 1, strlen( $hex ) );
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$rgb = hex_to_rgb( $hex_without_hash );
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$hsvl = rgb_to_hsvl( $rgb );
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return 'hsl( ' . $hsvl[0] . ',' . $hsvl[1] . '%,' . ( $hsvl[2] + $amount ) . '%)';
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}
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}
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