ฟังก์ชั่นเช็ค GIF ว่าเป็น Animation หรือไม่

function is_ani($filename) {
$filecontents = file_get_contents($filename);

$str_loc = 0;
$count = 0;
while ($count < 2) { # There is no point in continuing after we find a 2nd frame
$where1 = strpos($filecontents, “\x00\x21\xF9\x04”, $str_loc);
if ($where1 === FALSE) {
break;
} else {
$str_loc = $where1 + 1;
$where2 = strpos($filecontents, “\x00\x2C”, $str_loc);
if ($where2 === FALSE) {
break;
} else {
if ($where1 + 8 == $where2) {
$count++;
}
$str_loc = $where2 + 1;
}
}
}

if ($count > 1) {
return(true);
} else {
return(false);
}
}