Common::getImage

protected function getImage(HtmlDocument $document)
{
	$result = $document->getLinkHref('image_src');
	if($result <> '')
	{
		return $result;
	}

	foreach($this->imgElements as $imgElement)
	{
		if(isset($imgElement['rel']) && $imgElement['rel'] == 'image_src')
		{
			$result = $imgElement['src'];
			return $result;
		}
	}

	return null;
}