Fix the UI

Author: vmcj

webapp/src/Utils/Utils.php

@@ -352,10 +352,10 @@ public static function parseHexColor(string $hex): array
         $tmp = substr($hex, 1);
         if (strlen($tmp) % 3 == 0) {
             $mult = strlen($tmp) / 3;
-            $hex += 'f' * $mult;
+            $hex .= str_repeat("f", $mult);
         }
         // Source: https://stackoverflow.com/a/21966100
-        $length = (strlen($hex) - 1) / 3;
+        $length = (strlen($hex) - 1) / 4;
         $fact = [17, 1, 0.062272][$length - 1];
         return [
             (int)round(hexdec(substr($hex, 1, $length)) * $fact),
@@ -384,28 +384,28 @@ public static function rgbToHex(array $color): string
         $result = "#";
         if (count($color) === 3) {
             $color[] = 255;
-	} elseif (count($color) !== 4) {
+        } elseif (count($color) !== 4) {
             throw Exception("Invalid RGB number.");
-	}
-        for (int $i=0; $i<count($color); $i++) {
-            $result += static::componentToHex($color[$i]);
         }
+        for ($i=0; $i<count($color); $i++) {
+            $result .= static::componentToHex($color[$i]);
+	}
         return $result;
     }
 
     /**
      * @param array{int, int, int}|array{int, int, int, int} $rgba
-     * @param array{int, int, int}                           $bg
      *
      * @return array{int, int, int}
      */
-    public static function blendAlphaBackground(array $rgba, array $bg): array
+    public static function blendAlphaBackground(array $rgba, string $bg): array
     {
         if (count($rgba) === 3) {
             return $rgba;
 	} elseif (count($rgba) === 4) {
-            $result = [];
-            for (int $i=0; $i<3; $i++) {
+	    $result = [];
+            $bg = static::parseHexColor($bg);
+            for ($i=0; $i<3; $i++) {
                 $result[] = $rgba[$i] * $rgba[3] + $bg[$i] * (1 - $rgba[3]);
             }
 	    return $result;