PHPMailer\PHPMailer\PHPMailer::utf8CharBoundary PHP Method

utf8CharBoundary() public method

Original written by Colin Brown.
public utf8CharBoundary ( string $encodedText, integer $maxLength ) : integer
$encodedText string utf-8 QP text
$maxLength integer Find the last character boundary prior to this length
return integer
    public function utf8CharBoundary($encodedText, $maxLength)
    {
        $foundSplitPos = false;
        $lookBack = 3;
        while (!$foundSplitPos) {
            $lastChunk = substr($encodedText, $maxLength - $lookBack, $lookBack);
            $encodedCharPos = strpos($lastChunk, '=');
            if (false !== $encodedCharPos) {
                // Found start of encoded character byte within $lookBack block.
                // Check the encoded byte value (the 2 chars after the '=')
                $hex = substr($encodedText, $maxLength - $lookBack + $encodedCharPos + 1, 2);
                $dec = hexdec($hex);
                if ($dec < 128) {
                    // Single byte character.
                    // If the encoded char was found at pos 0, it will fit
                    // otherwise reduce maxLength to start of the encoded char
                    if ($encodedCharPos > 0) {
                        $maxLength = $maxLength - ($lookBack - $encodedCharPos);
                    }
                    $foundSplitPos = true;
                } elseif ($dec >= 192) {
                    // First byte of a multi byte character
                    // Reduce maxLength to split at start of character
                    $maxLength = $maxLength - ($lookBack - $encodedCharPos);
                    $foundSplitPos = true;
                } elseif ($dec < 192) {
                    // Middle byte of a multi byte character, look further back
                    $lookBack += 3;
                }
            } else {
                // No encoded character found
                $foundSplitPos = true;
            }
        }
        return $maxLength;
    }