Let's assume that your theme is NOT rolling its own gallery shortcode, and let's assume that you're using the [gallery] shortcode rather than the 'gallery' post format here. What you're looking for is the 'gallery_shortcode' function within wp-includes/media.php around line 750 (as of 3.3.1). That's where the HTML output of your gallery items is hard-coded.
Of course, we can't (well, we really shouldn't) edit or alter any of the WordPress core files, so we have to look at other ways to hook into, filter or otherwise enhance the built-in features with our own to add the 'title' and 'description' information you want for each attachment. Unfortunately the way the gallery shortcode was coded, there's no convenient filter that allows you to add to the content of each gallery item (which makes me think that it might be not a bad idea to submit an enhancement request and a patch... hmm...). So what we have to do instead is replace the entire shortcode function wholesale.
That's not as hard as it sounds, because we can just copy and paste the built-in code into our own plugin, and then add/modify/mutilate whatever we want.
Here's how you would do that. In order to make use of this code, simply create a file called 'WPSE45326_Gallery_Replacement.php" inside your plugins folder. Then you have to go into your Admin back-end and activate the new plugin. Then, just make sure the images have a Description and a Title.
Note: try this on a Vanilla WordPress install, first. If it works there, but not on your client's site, then it's because the theme you're using is rolling its own code. That would make things more complicated.
<?php
/*
Plugin Name: WPSE-45326 Gallery Replacement example
Plugin URI: http://wordpress.stackexchange.com/questions/45326
Description: A plugin to demonstrate how to replace the default 'gallery' shortcode and add additional HTML tags for more customization.
Version: 1.0
Author: Tom Auger
Author URI: http://www.tomauger.com
License: GPL2
*/
class wpse_45326_Gallery_Replacement {
function __construct(){
// Hook on the plugins-loaded action since it's the first real action hook that's available to us.
// However, if you're using a theme and want to replace that theme's `gallery` custom shortcode,
// you may need to use another action. Search through your parent theme's files for 'gallery' and see
// what hook it's using to define it's gallery shortcode, so you can make sure this code runs AFTER their code.
add_action( "init", array( __CLASS__, "init" ) );
}
function init(){
remove_shortcode( 'gallery' ); // Remove the default gallery shortcode implementation
add_shortcode( 'gallery', array( __CLASS__, "gallery_shortcode" ) ); // And replace it with our own!
}
/**
* The Gallery shortcode.
*
* This has been taken verbatim from wp-includes/media.php. There's a lot of good stuff in there.
* All you want to do is add some more HTML to it, and since (for some reason) they didn't provide more
* filters to be able to add, we have to replace the Gallery shortcode wholesale.
*
* @param array $attr Attributes of the shortcode.
* @return string HTML content to display gallery.
*/
function gallery_shortcode($attr) {
global $post;
static $instance = 0;
$instance++;
$output = apply_filters('post_gallery', '', $attr);
if ( $output != '' )
return $output;
if ( isset( $attr['orderby'] ) ) {
$attr['orderby'] = sanitize_sql_orderby( $attr['orderby'] );
if ( !$attr['orderby'] )
unset( $attr['orderby'] );
}
// NOTE: These are all the 'options' you can pass in through the shortcode definition, eg: [gallery itemtag='p']
extract(shortcode_atts(array(
'order' => 'ASC',
'orderby' => 'menu_order ID',
'id' => $post->ID,
'itemtag' => 'dl',
'icontag' => 'dt',
'captiontag' => 'dd',
'columns' => 3,
'size' => 'thumbnail',
'include' => '',
'exclude' => '',
// Here's the new options stuff we added to the shortcode defaults
'titletag' => 'p',
'descriptiontag' => 'p'
), $attr));
$id = intval($id);
if ( 'RAND' == $order )
$orderby = 'none';
if ( !empty($include) ) {
$include = preg_replace( '/[^0-9,]+/', '', $include );
$_attachments = get_posts( array('include' => $include, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => $order, 'orderby' => $orderby) );
$attachments = array();
foreach ( $_attachments as $key => $val ) {
$attachments[$val->ID] = $_attachments[$key];
}
} elseif ( !empty($exclude) ) {
$exclude = preg_replace( '/[^0-9,]+/', '', $exclude );
$attachments = get_children( array('post_parent' => $id, 'exclude' => $exclude, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => $order, 'orderby' => $orderby) );
} else {
$attachments = get_children( array('post_parent' => $id, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => $order, 'orderby' => $orderby) );
}
if ( empty($attachments) )
return '';
if ( is_feed() ) {
$output = "\n";
foreach ( $attachments as $att_id => $attachment )
$output .= wp_get_attachment_link($att_id, $size, true) . "\n";
return $output;
}
$itemtag = tag_escape($itemtag);
$captiontag = tag_escape($captiontag);
$columns = intval($columns);
$itemwidth = $columns > 0 ? floor(100/$columns) : 100;
$float = is_rtl() ? 'right' : 'left';
$selector = "gallery-{$instance}";
$gallery_style = $gallery_div = '';
if ( apply_filters( 'use_default_gallery_style', true ) )
$gallery_style = "
<style type='text/css'>
#{$selector} {
margin: auto;
}
#{$selector} .gallery-item {
float: {$float};
margin-top: 10px;
text-align: center;
width: {$itemwidth}%;
}
#{$selector} img {
border: 2px solid #cfcfcf;
}
#{$selector} .gallery-caption {
margin-left: 0;
}
</style>
<!-- see gallery_shortcode() in wp-includes/media.php -->";
$size_class = sanitize_html_class( $size );
$gallery_div = "<div id='$selector' class='gallery galleryid-{$id} gallery-columns-{$columns} gallery-size-{$size_class}'>";
$output = apply_filters( 'gallery_style', $gallery_style . "\n\t\t" . $gallery_div );
$i = 0;
foreach ( $attachments as $id => $attachment ) {
$link = isset($attr['link']) && 'file' == $attr['link'] ? wp_get_attachment_link($id, $size, false, false) : wp_get_attachment_link($id, $size, true, false);
$output .= "<{$itemtag} class='gallery-item'>";
$output .= "
<{$icontag} class='gallery-icon'>
$link
</{$icontag}>";
// MODIFICATION: include the title and description HTML if we've supplied the relevant shortcode parameters (titletag, descriptiontag)
if ( $captiontag ) {
$output .= "
<{$captiontag} class='wp-caption-text gallery-caption'>";
// The CAPTION, if there is one
if ( trim( $attachment->post_excerpt ) ) {
$output .= "
" . wptexturize($attachment->post_excerpt);
}
// The TITLE, if we've not made the 'titletag' param blank
if ( $titletag ){
$output .= "
<{$titletag} class=\"gallery-item-title\">" . $attachment->post_title . "</{$titletag}>";
}
// The DESCRIPTION, if we've not specified a blank 'descriptiontag'
if ( $descriptiontag ){
$output .= "
<{$descriptiontag} class=\"gallery-item-description\">" . wptexturize( $attachment->post_content ) . "</{$descriptiontag}>";
}
$option .= "
</{$captiontag}>";
}
$output .= "</{$itemtag}>";
if ( $columns > 0 && ++$i % $columns == 0 )
$output .= '<br style="clear: both" />';
}
$output .= "
<br style='clear: both;' />
</div>\n";
return $output;
}
}
new wpse_45326_Gallery_Replacement();
galleryshortcode. So it must be your theme that's adding that stuff in - which makes it harder for us to give you a general answer since each theme could approach it differently.