intermédiaire - no use

global/inc/colors.php

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