private function print_diff_content() {
        global $CFG, $OUTPUT, $PAGE;

        $pageid = $this->page->id;
        $total = wiki_count_wiki_page_versions($pageid) - 1;

        $oldversion = wiki_get_wiki_page_version($pageid, $this->compare);

        $newversion = wiki_get_wiki_page_version($pageid, $this->comparewith);

        if ($oldversion && $newversion) {

            $oldtext = format_text(file_rewrite_pluginfile_urls($oldversion->content, 'pluginfile.php', $this->modcontext->id, 'mod_wiki', 'attachments', $this->subwiki->id));
            $newtext = format_text(file_rewrite_pluginfile_urls($newversion->content, 'pluginfile.php', $this->modcontext->id, 'mod_wiki', 'attachments', $this->subwiki->id));
            list($diff1, $diff2) = ouwiki_diff_html($oldtext, $newtext);
            $oldversion->diff = $diff1;
            $oldversion->user = wiki_get_user_info($oldversion->userid);
            $newversion->diff = $diff2;
            $newversion->user = wiki_get_user_info($newversion->userid);

            echo $this->wikioutput->diff($pageid, $oldversion, $newversion, array('total' => $total));
        } else {
            print_error('versionerror', 'wiki');
        }
    }