WordPress gallery Hack, Make your own styling and add your own CSS, JavaScript and spice it up

WP-Gallery-Extend

<?php

/* 

I grabbed this form WordPress Galleria Plugin, I prefer using this in functions.php rather than a plugin 

*/

remove_shortcode('gallery');
add_shortcode('gallery', 'photo_gallery_shortcode');




function photo_gallery_shortcode($attr) {

global $post;
$pid = $post->ID;
$image_size = "500px";

	// 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(
		'orderby' => 'menu_order ASC, ID ASC',
		'id' => $post->ID,
		'size' => $image_size,
	), $attr));

	$id = intval($id);
	$attachments = get_children("post_parent=$id&post_type=attachment&post_mime_type=image&orderby={$orderby}");

	if ( empty($attachments) )
		return '';

	if ( is_feed() ) {
		$output = "\n";
		foreach ( $attachments as $id => $attachment )
			$output .= wp_get_attachment_link($id, $size, true) . "\n";
		return $output;
	}

	// Build  and markup it
	$output = apply_filters('gallery_style', '<div id="gallery-' . $pid . '">');
	$output .= ('<!-- Begin -->');

	// Loop through each image
	foreach ( $attachments as $id => $attachment ) {
		
		// Attachment page ID
		$att_page = get_attachment_link($id);
		// Returns array
		$img = wp_get_attachment_image_src($id, $image_size);
		$img = $img[0];
		$thumb = wp_get_attachment_image_src($id, 'thumbnail');
		$thumb = $thumb[0];
		// Set the image titles
		$title = $attachment->post_title;
		// Get the Permalink
		$permalink = get_permalink();
		// Set the image captions
		$description = htmlspecialchars($attachment->post_content, ENT_QUOTES);
		if($description == '') $description = htmlspecialchars($attachment->post_excerpt, ENT_QUOTES);

		// Build html for each image
		$output .= '<div class="thumbnail">';
		$output .= "<a href='".$img."'>";
		$output .= "<img src='".$thumb."' longdesc='".$permalink."' alt='".$description."' title='".$description."' />";
		$output .= "</a>";

		/*
		 if you planing to add title and descriptions
		$output .= "<strong>".$title."</strong>";
		$output .= "<span>".$description."</span>";
		*/
		$output .= "</div>";
	
	// End foreach
	}
	
	// Close markup
	$output .= "</div>";
	$output .= "<!-- Ends :)  -->";
	return $output;
}