The function will add first image from the question content to the questions list

qa_list_q_thumb.php

<?php
/**
 * Add first image to the question list
 * 
 * Declearation
 * Base code is taken from Mouseover Layer plugin
 * 
 * Than I have extracted content using preg_match_all to get first image
 * and assing that to the q_list
 * 
 * How to use it:
 * Nothing complicated, just place 'q_list' method into your theme or plugin file and done.
 * 
 * Important:
 * Make sure your theme should not have this function already. If there is than add this code
 * to that function and modify as needed
 * 
 * @param array $q_list
 * @category Hook
 * @since 1.7
 * @author Q2A Market <dev@q2amarket.com>
 * @link http://www.q2amarket.com Q2A Market
 * @license http://www.gnu.org/copyleft/gpl.html GNU General Public License
 */
public function q_list($q_list)
{

    if (!empty($q_list['qs'])) { // first check it is not an empty list and the feature is turned on
        // Collect the question ids of all items in the question list (so we can do this in one DB query)
        $postids = array();
        foreach ($q_list['qs'] as $question)
        {
            if (isset($question['raw']['postid']))
                $postids[] = $question['raw']['postid'];
        }

        if (!empty($postids)) {

            // Retrieve the content for these questions from the database and put into an array fetching
            // the minimal amount of characters needed to determine the string should be shortened or not

            $result   = qa_db_query_sub('SELECT postid, content, format FROM ^posts WHERE postid IN (#)', $postids);
            $postinfo = qa_db_read_all_assoc($result, 'postid');

            // Get the regular expression fragment to use for blocked words and the maximum length of content to show
            $blockwordspreg = qa_get_block_words_preg();

            // Now add the popup to the title for each question
            foreach ($q_list['qs'] as $index => $question)
            {
                if (isset($postinfo[$question['raw']['postid']])) {
                    $thispost = $postinfo[$question['raw']['postid']];
                    $text     = qa_viewer_html($thispost['content'], $thispost['format'], array('blockwordspreg' => $blockwordspreg));

                    // Extract image source from content
                    preg_match_all('/<img[^>]+src=[\'"]([^\'"]+)[\'"][^>]*>/i', $text, $matches);

                    // If content has image than show it!
                    if (!empty($matches[0])) {

                        // assign image to the variable
                        $image                           = '<img src="' . $matches[1][0] . '" alt="image" class="q-list-image" width="64"/>'; // change the size using attr or css
                        $q_list['qs'][$index]['content'] = $image;
                    }
                }
            }
        }
    }

    qa_html_theme_base::q_list($q_list);
}