Warn on non-opaque colors for problems

Author: vmcj

webapp/src/Service/CheckConfigService.php

@@ -474,6 +474,9 @@ public function checkContestsValidate(): ConfigCheckItem
                 if (empty($cp->getColor())) {
                     $result = ($result === 'E' ? 'E' : 'W');
                     $cperrors[$cid] .= "  - No color for problem `" . $cp->getShortname() . "` in contest c" . $cid . "\n";
+                } elseif (Utils::parseHexColor($cp->getColor())[3] !== 255) {
+                    $result = ($result === 'E' ? 'E' : 'W');
+                    $cperrors[$cid] .= "  - Semi-transparent color for problem `" . $cp->getShortname() . "` in contest c" . $cid . "\n";
                 }
             }
         }

webapp/src/Utils/Utils.php

@@ -343,19 +343,24 @@ public static function convertToColor(string $hex): ?string
     }
 
     /**
-     * Parse a hex color into it's three RGB values.
+     * Parse a hex color into it's four RGBA values.
      *
-     * @return array{int, int, int}
+     * @return array{int, int, int, int}
      */
     public static function parseHexColor(string $hex): array
     {
         // Source: https://stackoverflow.com/a/21966100
-        $length = (strlen($hex) - 1) / 3;
+        $length = (strlen($hex) - 1) / 4;
+        if (((strlen($hex) - 1) % 3) == 0) {
+            $length = (strlen($hex) - 1) / 3;
+            $hex .= str_repeat('F', $length);
+        }
         $fact = [17, 1, 0.062272][$length - 1];
         return [
             (int)round(hexdec(substr($hex, 1, $length)) * $fact),
             (int)round(hexdec(substr($hex, 1 + $length, $length)) * $fact),
-            (int)round(hexdec(substr($hex, 1 + 2 * $length, $length)) * $fact)
+            (int)round(hexdec(substr($hex, 1 + 2 * $length, $length)) * $fact),
+            (int)round(hexdec(substr($hex, 1 + 3 * $length, $length)))
         ];
     }
 

webapp/tests/Unit/Utils/UtilsTest.php

@@ -321,10 +321,10 @@ public function testConvertToHexConvert(): void
 
     public function testParseHexColor(): void
     {
-        self::assertEquals([255, 255, 255], Utils::parseHexColor('#ffffff'));
-        self::assertEquals([0, 0, 0], Utils::parseHexColor('#000000'));
-        self::assertEquals([171, 205, 239], Utils::parseHexColor('#abcdef'));
-        self::assertEquals([254, 220, 186], Utils::parseHexColor('#FEDCBA'));
+        self::assertEquals([255, 255, 255, 255], Utils::parseHexColor('#ffffff'));
+        self::assertEquals([0, 0, 0, 255], Utils::parseHexColor('#000000'));
+        self::assertEquals([171, 205, 239, 255], Utils::parseHexColor('#abcdef'));
+        self::assertEquals([254, 220, 186, 255], Utils::parseHexColor('#FEDCBA'));
     }
 
     public function testComponentToHex(): void