Merge pull request #42 from felixhahnweilheim/fix-41

Fix division by zero

docs/CHANGELOG.md

@@ -1,3 +1,6 @@
+## TBA
+- Fix #42: Division by zero (when trying to lighten white color)
+
 ## 0.3.0 (14 february 2024)
 **NOTE** Files in themes/FlexTheme/css now need to be writable by the PHP process (see https://docs.humhub.org/docs/admin/installation/#file-permissions)
 

helpers/ColorHelper.php

@@ -10,7 +10,6 @@ class ColorHelper
      */
     public static function lighten(string $color, int $amount, bool $relative = false): string
     {
-
         /*
          * $color is expected to be a hexadecimal color code (including '#')
          * and has to be splitted into its components
@@ -29,9 +28,15 @@ public static function lighten(string $color, int $amount, bool $relative = fals
              */
             $max = hexdec(max($color_parts));
             $min = hexdec(min($color_parts));
-            if ($max != 0) {
-                $percentage = $percentage / (1 - ($max + $min) / (2 * 255));
+
+            /*
+             * if $min is 255, we would divide by zero below
+             * and white #ffffff does not need lightening anyways
+             */
+            if ($min == 255) {
+                return $color;
             }
+            $percentage = $percentage / (1 - ($max + $min) / (2 * 255));
         }
 
         $return = '#';
@@ -81,7 +86,6 @@ public static function darken(string $color, int $amount, bool $relative = false
 
     public static function fade(string $color, int $amount): string
     {
-
         // $amount is expected to be between 0 and 100
         $opacity = ($amount / 100) * 255;
         $opacity = max(min($opacity, 255), 0); // keep between 0 and 255