caption on featured image

// 27/01/2012 alchymyth
// show thumbnail with caption, if available, wrapped with '.wp-caption thumb-caption' div;
// show just the thumbnail otherwise
// for featured images in the loop
add_filter('post_thumbnail_html','add_post_thumbnail_caption',10,5);
function add_post_thumbnail_caption($html, $post_id, $post_thumbnail_id, $size, $attr) {

if( $html == '' || !in_the_loop() ) {

    return $html;

} else {

    $out = '';

  $thumbnail_image = get_posts(array('p' => $post_thumbnail_id, 'post_type' => 'attachment'));

  if ($thumbnail_image && isset($thumbnail_image[0])) {

  $image = wp_get_attachment_image_src($post_thumbnail_id, $size);
  $t_width = $image[1] +10; // +10 here for extra padding, needs to be considered in writing css - the default image caption uses +10;
  $class = $attr['class'];
    if($thumbnail_image[0]->post_excerpt) $out .= '<div class="wp-caption thumb-caption '.$class.'" style="width:'.$t_width.'px; ">';

    $out .= $html;

    if($thumbnail_image[0]->post_excerpt) $out .= '<p class="wp-caption-text">'.$thumbnail_image[0]->post_excerpt.'</p></div>';
  }
return $out;
}
/*css classes for this:
.wp-caption.thumb-caption { ... }
.wp-caption.thumb-caption img { ... }
.wp-caption.thumb-caption .wp-caption-text { ... }
*/
}