1 files changed, 121 insertions, 0 deletions
diff --git a/library/Icinga/Util/Color.php b/library/Icinga/Util/Color.php
new file mode 100644
index 0000000..cf88f41
--- /dev/null
+++ b/library/Icinga/Util/Color.php
@@ -0,0 +1,121 @@
+<?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;
+    }
+}