Piwik RSS feed tracking via blind pixels

functions.php

// Add this to the functions.php of your wordpress Theme. Get the URL for the tracking pixel from your Piwik instance.

function feedFilter($query) {
    if ($query->is_feed) {
        add_filter('the_content','feedContentFilter');
    }
    return $query;
}
add_filter('pre_get_posts','feedFilter');


function feedContentFilter($content) {
	return $content.'<img src="http://xxx.org/piwik.php?idsite=x&rec=1&action_name='.get_the_title().'" style="border:0" alt="" />';
}