/**
  * Calculate the left and top offset of the barcode in the
  * rendering support
  *
  * @param float $supportHeight
  * @param float $supportWidth
  * @return void
  */
 protected function _adjustPosition($supportHeight, $supportWidth)
 {
     $barcodeHeight = $this->_barcode->getHeight(true) * $this->_moduleSize;
     if ($barcodeHeight != $supportHeight && $this->_topOffset == 0) {
         switch ($this->_verticalPosition) {
             case 'middle':
                 $this->_topOffset = floor(($supportHeight - $barcodeHeight) / 2);
                 break;
             case 'bottom':
                 $this->_topOffset = $supportHeight - $barcodeHeight;
                 break;
             case 'top':
             default:
                 $this->_topOffset = 0;
                 break;
         }
     }
     $barcodeWidth = $this->_barcode->getWidth(true) * $this->_moduleSize;
     if ($barcodeWidth != $supportWidth && $this->_leftOffset == 0) {
         switch ($this->_horizontalPosition) {
             case 'center':
                 $this->_leftOffset = floor(($supportWidth - $barcodeWidth) / 2);
                 break;
             case 'right':
                 $this->_leftOffset = $supportWidth - $barcodeWidth;
                 break;
             case 'left':
             default:
                 $this->_leftOffset = 0;
                 break;
         }
     }
 }