/**
* Calculate the width of a string:
* in case of using alignment parameter in drawText
* @param string $text
* @param Zend_Pdf_Font $font
* @param float $fontSize
* @return float
*/
public function widthForStringUsingFontSize($text, $font, $fontSize)
{
$drawingString = iconv('UTF-8', 'UTF-16BE//IGNORE', $text);
$characters = array();
for ($i = 0; $i < strlen($drawingString); $i++) {
$characters[] = ord($drawingString[$i++]) << 8 | ord($drawingString[$i]);
}
$glyphs = $font->glyphNumbersForCharacters($characters);
$widths = $font->widthsForGlyphs($glyphs);
$stringWidth = array_sum($widths) / $font->getUnitsPerEm() * $fontSize;
return $stringWidth;
}