Bug-fix.

Changelog excerpt:
- PDF files were sometimes being flagged as images; Fixed.

Also slightly refactored some regex.

Author: Maikuolan

Changelog.md

@@ -99,3 +99,5 @@ __*Why "v3.0.0" instead of "v1.0.0?"*__ Prior to phpMussel v3, the "phpMussel Co
 ### v3.3.4
 
 [2022.11.30; Maikuolan]: Adjusted minimum value for some port directives from 1 to 0.
+
+[2022.12.26; Bug-fix; Maikuolan]: PDF files were sometimes being flagged as images; Fixed.

src/Scanner.php

@@ -8,7 +8,7 @@
  * License: GNU/GPLv2
  * @see LICENSE.txt
  *
- * This file: The scanner (last modified: 2022.08.20).
+ * This file: The scanner (last modified: 2022.12.26).
  */
 
 namespace phpMussel\Core;
@@ -3125,12 +3125,13 @@ private function imageIndicators(string $Ext, string $Head): bool
     {
         return (
             preg_match(
-                '/^(?:bm[2p]|c(d5|gm)|d(ib|w[fg]|xf)|ecw|fits|gif|img|j(f?if?|p[2s]|pe?g?2?|xr)|p(bm|cx|dd|gm|ic|n[gms]|' .
-                'pm|s[dp])|s(id|v[ag])|tga|w(bmp?|ebp|mp)|x(cf|bmp))$/',
+                '/^(?:bm[2p]|cd5|cgm|d(?:ib|w[fg]|xf)|ecw|fits|gif|img|j(?:f?if?|p[2s' .
+                ']|pe?g?2?|xr)|p(?:bm|cx|dd|gm|ic|n[gms]|pm|s[dp])|s(?:id|v[ag])|tga|' .
+                'w(?:bmp?|ebp|mp)|xcf|xbmp)$/',
                 $Ext
             ) ||
             preg_match(
-                '/^(?:0000000c6a502020|25504446|38425053|424d|474946383[79]61|57454250|67696d7020786366|89504e47|ffd8ff)/',
+                '/^(?:0000000c6a502020|38425053|424d|474946383[79]61|57454250|67696d7020786366|89504e47|ffd8ff)/',
                 $Head
             )
         );