How to make a slideshow shortcode based on the Wordpress gallery shortcode? [closed]

Question

This is the wordpress function for the gallery shortcode, i would like to understand how this works so i can implement a slideshow shortcode and adding the img id only as gallery shortcode does.

    function gallery_shortcode($attr) {
$post = get_post();

static $instance = 0;
$instance++;

if ( ! empty( $attr['ids'] ) ) {
    // 'ids' is explicitly ordered, unless you specify otherwise.
    if ( empty( $attr['orderby'] ) )
        $attr['orderby'] = 'post__in';
    $attr['include'] = $attr['ids'];
}

// 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 ? $post->ID : 0,
    'itemtag'    => 'dl',
    'icontag'    => 'dt',
    'captiontag' => 'dd',
    'columns'    => 3,
    'size'       => 'thumbnail',
    'include'    => '',
    'exclude'    => '',
    'link'       => ''
), $attr, 'gallery'));

$id = intval($id);
if ( 'RAND' == $order )
    $orderby = 'none';

if ( !empty($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) ) {
    $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);
$icontag = tag_escape($icontag);
$valid_tags = wp_kses_allowed_html( 'post' );
if ( ! isset( $valid_tags[ $itemtag ] ) )
    $itemtag = 'dl';
if ( ! isset( $valid_tags[ $captiontag ] ) )
    $captiontag = 'dd';
if ( ! isset( $valid_tags[ $icontag ] ) )
    $icontag = 'dt';

$columns = intval($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;
        }
        /* see gallery_shortcode() in wp-includes/media.php */
    </style>";
$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 ) {
    if ( ! empty( $link ) && 'file' === $link )
        $image_output = wp_get_attachment_link( $id, $size, false, false );
    elseif ( ! empty( $link ) && 'none' === $link )
        $image_output = wp_get_attachment_image( $id, $size, false );
    else
        $image_output = wp_get_attachment_link( $id, $size, true, false );

    $image_meta  = wp_get_attachment_metadata( $id );

    $orientation = '';
    if ( isset( $image_meta['height'], $image_meta['width'] ) )
        $orientation = ( $image_meta['height'] > $image_meta['width'] ) ? 'portrait' : 'landscape';

    $output .= "<{$itemtag} class='gallery-item'>";
    $output .= "
        <{$icontag} class='gallery-icon {$orientation}'>
            $image_output
        </{$icontag}>";
    if ( $captiontag && trim($attachment->post_excerpt) ) {
        $output .= "
            <{$captiontag} class='wp-caption-text 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;

Answer 1

I would do something similar to this:

return '<div class="slideshow">'.do_shortcode( '[gallery ids="'.$attr['ids'].'"]' ).'</div>';

In other words, wrap around the existing short code instead of ending up with a frankenstein version of it. You can then use the slideshow div to select against using jquery and whichever javascript gallery you want to use. How you would do that is beyond the scope of this site