Testing wordpress gallery filter and image attachment template

Start with wordpress 2.5, media managing has been significantly improved. However, there is just not enough document available online correctly address it.

I found a web page saying pass customized function to post_gallery to modify the output of gallery display. Here is the sample code.

add_filter('post_gallery', 'kg_gallery_shortcode');
function kg_gallery_shortcode($attr) {
	global $post;
	extract(shortcode_atts(array(
		'id' => $post->ID,
		'ex' => ''
	), $attr));

/* ... */
}

The default gallery display called by gallery_shortcode (in wp-includes/media.php, code attached at the end of this post) is not bad. As you can see

When I clicked any image thumbnail and the linked pages were really bad. Base on this page from wordpress, I started looking for a file called attachment.php. I could not! However, in the default theme, there is a file called image.php (Image Attachment Template). I merged it with code from my single.php. All good now.

image attachment template image.php in the default wordpress theme

<?php
/**
 * <a href="http://twitter.com/package" target="_blank" class="litwitter">@package</a> WordPress
 * <a href="http://twitter.com/subpackage" target="_blank" class="litwitter">@subpackage</a> Default_Theme
 */
 get_header();
?>
	<div id="content" class="widecolumn">
  <?php if (have_posts()) : while (have_posts()) : the_post(); ?>
		<div class="post" id="post-<?php the_ID(); ?>">
			<h2><a href="<?php echo get_permalink($post->post_parent); ?>" rev="attachment"><?php echo get_the_title($post->post_parent); ?></a> &raquo; <?php the_title(); ?></h2>
			<div class="entry">
				<p class="attachment"><a href="<?php echo wp_get_attachment_url($post->ID); ?>"><?php echo wp_get_attachment_image( $post->ID, 'medium' ); ?></a>
				<div class="caption"><?php if ( !empty($post->post_excerpt) ) the_excerpt(); // this is the "caption" ?></div>
				<?php the_content('<p class="serif">Read the rest of this entry &raquo;'); ?>
				<div class="navigation">
					<div class="alignleft"><?php previous_image_link() ?></div>
					<div class="alignright"><?php next_image_link() ?></div>
				</div>
				<br class="clear" />
				<p class="postmetadata alt">
					<small>
						This entry was posted on <?php the_time('l, F jS, Y') ?> at <?php the_time() ?>
						and is filed under <?php the_category(', ') ?>.
						<?php the_taxonomies(); ?>
						You can follow any responses to this entry through the <?php post_comments_feed_link('RSS 2.0'); ?> feed.
						<?php if ( comments_open() && pings_open() ) {
							// Both Comments and Pings are open ?>
							You can <a href="#respond">leave a response</a>, or <a href="<?php trackback_url(); ?>" rel="trackback">trackback</a> from your own site.
						<?php } elseif ( !comments_open() && pings_open() ) {
							// Only Pings are Open ?>
							Responses are currently closed, but you can <a href="<?php trackback_url(); ?> " rel="trackback">trackback</a> from your own site.
						<?php } elseif ( comments_open() && !pings_open() ) {
							// Comments are open, Pings are not ?>
							You can skip to the end and leave a response. Pinging is currently not allowed.
						<?php } elseif ( !comments_open() && !pings_open() ) {
							// Neither Comments, nor Pings are open ?>
							Both comments and pings are currently closed.
						<?php } edit_post_link('Edit this entry.','',''); ?>
					</small>
				
			</div>
		</div>
	<?php comments_template(); ?>
	<?php endwhile; else: ?>
		
Sorry, no attachments matched your criteria.
<?php endif; ?>
	</div>
<?php get_footer(); ?>

wp-includes/media.php containing gallery_shortcode

add_shortcode('gallery', 'gallery_shortcode');
/**
 * The Gallery shortcode.
 *
 * This implements the functionality of the Gallery Shortcode for displaying
 * WordPress images on a post.
 *
 * <a href="http://twitter.com/since" target="_blank" class="litwitter">@since</a> 2.5.0
 *
 * <a href="http://twitter.com/param" target="_blank" class="litwitter">@param</a> array $attr Attributes attributed to the shortcode.
 * <a href="http://twitter.com/return" target="_blank" class="litwitter">@return</a> string HTML content to display gallery.
 */
function gallery_shortcode($attr) {
	global $post, $wp_locale;
	static $instance = 0;
	$instance++;
	// Allow plugins/themes to override the default gallery template.
	$output = apply_filters('post_gallery', '', $attr);
	if ( $output != '' )
		return $output;
	// We're trusting author input, so let's at least make sure it looks like a valid orderby statement
	if ( isset( $attr['orderby'] ) ) {
		$attr['orderby'] = sanitize_sql_orderby( $attr['orderby'] );
		if ( !$attr['orderby'] )
			unset( $attr['orderby'] );
	}
	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'    => ''
	), $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 = $wp_locale->text_direction == 'rtl' ? 'right' : 'left'; 
	$selector = "gallery-{$instance}";
	$output = apply_filters('gallery_style', "
		<style type='text/css'>
			#{$selector} {
				margin: auto;
			}
			#{$selector} .gallery-item {
				float: {$float};
				margin-top: 10px;
				text-align: center;
				width: {$itemwidth}%;			}
			#{$selector} img {
				border: 2px solid #cfcfcf;
			}
			#{$selector} .gallery-caption {
				margin-left: 0;
			}
		</style>
		<!-- see gallery_shortcode() in wp-includes/media.php -->
		<div id='$selector' class='gallery galleryid-{$id}'>");
	$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}>";
		if ( $captiontag && trim($attachment->post_excerpt) ) {
			$output .= "
				<{$captiontag} class='gallery-caption'>
				" . wptexturize($attachment->post_excerpt) . "
				</{$captiontag}>";
		}
		$output .= "</{$itemtag}>";
		if ( $columns > 0 && ++$i % $columns == 0 )
			$output .= '<br style="clear: both" />';
	}
	$output .= "
			<br style='clear: both;' />
		</div>\n";
	return $output;
}

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