124 lines
4.5 KiB
PHP
124 lines
4.5 KiB
PHP
<?php
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class ColorGradient
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{
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public $pct;
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public $color;
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public static function RGB2HSV($R, $G, $B) // RGB values: 0-255, 0-255, 0-255
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{ // HSV values: 0-360, 0-100, 0-100
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// Convert the RGB byte-values to percentages
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$R = ($R / 255);
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$G = ($G / 255);
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$B = ($B / 255);
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// Calculate a few basic values, the maximum value of R,G,B, the
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// minimum value, and the difference of the two (chroma).
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$maxRGB = max($R, $G, $B);
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$minRGB = min($R, $G, $B);
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$chroma = $maxRGB - $minRGB;
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// Value (also called Brightness) is the easiest component to calculate,
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// and is simply the highest value among the R,G,B components.
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// We multiply by 100 to turn the decimal into a readable percent value.
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$computedV = 100 * $maxRGB;
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// Special case if hueless (equal parts RGB make black, white, or grays)
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// Note that Hue is technically undefined when chroma is zero, as
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// attempting to calculate it would cause division by zero (see
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// below), so most applications simply substitute a Hue of zero.
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// Saturation will always be zero in this case, see below for details.
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if ($chroma == 0)
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return array(0, 0, $computedV);
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// Saturation is also simple to compute, and is simply the chroma
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// over the Value (or Brightness)
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// Again, multiplied by 100 to get a percentage.
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$computedS = 100 * ($chroma / $maxRGB);
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// Calculate Hue component
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// Hue is calculated on the "chromacity plane", which is represented
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// as a 2D hexagon, divided into six 60-degree sectors. We calculate
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// the bisecting angle as a value 0 <= x < 6, that represents which
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// portion of which sector the line falls on.
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if ($R == $minRGB)
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$h = 3 - (($G - $B) / $chroma);
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elseif ($B == $minRGB)
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$h = 1 - (($R - $G) / $chroma);
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else // $G == $minRGB
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$h = 5 - (($B - $R) / $chroma);
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// After we have the sector position, we multiply it by the size of
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// each sector's arc (60 degrees) to obtain the angle in degrees.
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$computedH = 60 * $h;
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return array($computedH, $computedS, $computedV);
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}
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public static function HSV2RGB($h, $s, $v)
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{
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$s /= 256.0;
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if ($s == 0.0) return array($v,$v,$v);
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$h /= (256.0 / 6.0);
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$i = floor($h);
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$f = $h - $i;
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$p = (integer)($v * (1.0 - $s));
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$q = (integer)($v * (1.0 - $s * $f));
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$t = (integer)($v * (1.0 - $s * (1.0 - $f)));
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switch($i) {
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case 0: return array($v,$t,$p);
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case 1: return array($q,$v,$p);
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case 2: return array($p,$v,$t);
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case 3: return array($p,$q,$v);
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case 4: return array($t,$p,$v);
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default: return array($v,$p,$q);
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}
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}
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public static function gradient($from_color, $to_color, $graduations = 10)
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{
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$graduations--;
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$startcol = str_replace("#", "", $from_color);
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$endcol = str_replace("#", "", $to_color);
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$RedOrigin = hexdec(substr($startcol, 0, 2));
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$GrnOrigin = hexdec(substr($startcol, 2, 2));
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$BluOrigin = hexdec(substr($startcol, 4, 2));
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if ($graduations >= 2) { // for at least 3 colors
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$GradientSizeRed = (hexdec(substr($endcol, 0, 2)) - $RedOrigin) / $graduations; //Graduation Size Red
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$GradientSizeGrn = (hexdec(substr($endcol, 2, 2)) - $GrnOrigin) / $graduations;
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$GradientSizeBlu = (hexdec(substr($endcol, 4, 2)) - $BluOrigin) / $graduations;
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for ($i = 0; $i <= $graduations; $i++) {
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$RetVal[$i] = strtoupper("#" . str_pad(dechex($RedOrigin + ($GradientSizeRed * $i)), 2, '0', STR_PAD_LEFT) .
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str_pad(dechex($GrnOrigin + ($GradientSizeGrn * $i)), 2, '0', STR_PAD_LEFT) .
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str_pad(dechex($BluOrigin + ($GradientSizeBlu * $i)), 2, '0', STR_PAD_LEFT));
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}
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} elseif ($graduations == 1) { // exactlly 2 colors
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$RetVal[] = $from_color;
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$RetVal[] = $to_color;
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} else { // one color
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$RetVal[] = $from_color;
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}
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return $RetVal;
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}
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public static function hex2rgb($hex)
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{
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return sscanf($hex, "#%02x%02x%02x");
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}
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// ---
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// --- Local fonctions
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// ---
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public static function rgb2hex($rgb)
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{
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$hex = "#";
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$hex .= str_pad(dechex($rgb[0]), 2, "0", STR_PAD_LEFT);
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$hex .= str_pad(dechex($rgb[1]), 2, "0", STR_PAD_LEFT);
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$hex .= str_pad(dechex($rgb[2]), 2, "0", STR_PAD_LEFT);
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return $hex; // returns the hex value including the number sign (#)
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}
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}
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?>
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