+ /**
+ * Checks if a string contains multibyte characters.
+ * @access private
+ * @param string $str multi-byte text to wrap encode
+ * @return bool
+ */
+ function HasMultiBytes($str) {
+ if (function_exists('mb_strlen')) {
+ return (strlen($str) > mb_strlen($str, $this->CharSet));
+ } else { // Assume no multibytes (we can't handle without mbstring functions anyway)
+ return False;
+ }
+ }
+
+ /**
+ * Correctly encodes and wraps long multibyte strings for mail headers
+ * without breaking lines within a character.
+ * Adapted from a function by paravoid at http://uk.php.net/manual/en/function.mb-encode-mimeheader.php
+ * @access private
+ * @param string $str multi-byte text to wrap encode
+ * @return string
+ */
+ function Base64EncodeWrapMB($str) {
+ $start = "=?".$this->CharSet."?B?";
+ $end = "?=";
+ $encoded = "";
+
+ $mb_length = mb_strlen($str, $this->CharSet);
+ // Each line must have length <= 75, including $start and $end
+ $length = 75 - strlen($start) - strlen($end);
+ // Average multi-byte ratio
+ $ratio = $mb_length / strlen($str);
+ // Base64 has a 4:3 ratio
+ $offset = $avgLength = floor($length * $ratio * .75);
+
+ for ($i = 0; $i < $mb_length; $i += $offset) {
+ $lookBack = 0;
+
+ do {
+ $offset = $avgLength - $lookBack;
+ $chunk = mb_substr($str, $i, $offset, $this->CharSet);
+ $chunk = base64_encode($chunk);
+ $lookBack++;
+ }
+ while (strlen($chunk) > $length);
+
+ $encoded .= $chunk . $this->LE;
+ }
+
+ // Chomp the last linefeed
+ $encoded = substr($encoded, 0, -strlen($this->LE));
+ return $encoded;
+ }
+