/** * Returns a number between 0 and 1 inclusive that indicates the percentage * of characters in the string which are covered by glyphs in this font. * * Since no one font will contain glyphs for the entire Unicode character * range, this method can be used to help locate a suitable font when the * actual contents of the string are not known. * * Note that some fonts lie about the characters they support. Additionally, * fonts don't usually contain glyphs for control characters such as tabs * and line breaks, so it is rare that you will get back a full 1.0 score. * The resulting value should be considered informational only. * * @param string $string * @param string $charEncoding (optional) Character encoding of source text. * If omitted, uses 'current locale'. * @return float */ public function getCoveredPercentage($string, $charEncoding = '') { /* Convert the string to UTF-16BE encoding so we can match the string's * character codes to those found in the cmap. */ if ($charEncoding != 'UTF-16BE') { if (PHP_OS != 'AIX') { // AIX doesnt know what UTF-16BE is $string = iconv($charEncoding, 'UTF-16BE', $string); } } $charCount = PHP_OS != 'AIX' ? iconv_strlen($string, 'UTF-16BE') : strlen($string); if ($charCount == 0) { return 0; } /* Fetch the covered character code list from the font's cmap. */ $coveredCharacters = $this->_cmap->getCoveredCharacters(); /* Calculate the score by doing a lookup for each character. */ $score = 0; $maxIndex = strlen($string); for ($i = 0; $i < $maxIndex; $i++) { /** * @todo Properly handle characters encoded as surrogate pairs. */ $charCode = ord($string[$i]) << 8 | ord($string[++$i]); /* This could probably be optimized a bit with a binary search... */ if (in_array($charCode, $coveredCharacters)) { $score++; } } return $score / $charCount; }