A simplification for Wordpress gallery shortcode output

functions.php

<?php

// Thumbnails
  add_theme_support( 'post-thumbnails' );
  add_image_size( 'image_1024', 1024, 1024 );

// Gallery
  function simplier_gallery($attr) {
     $post = get_post();
    static $instance = 0;
    $instance++;

    if ( ! empty( $attr['ids'] ) ) {
        if ( empty( $attr['orderby'] ) )
            $attr['orderby'] = 'post__in';
        $attr['include'] = $attr['ids'];
    }

    $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'] );
    }

    extract(shortcode_atts(array(
      'order'      => 'ASC',
      'orderby'    => 'menu_order ID',
      'id'         => $post->ID,
      'itemtag'    => 'li',
      'icontag'    => '',
      'captiontag' => '',
      'columns'    => 3,
      'size'       => 'image_1024',
      'zoomsize'       => 'large',
      'include'    => '',
      'exclude'    => ''
    ), $attr));

    $id = intval($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;
    }

    $output = "<ul class='gallery'>";
    $output .= "";
    foreach ( $attachments as $id => $attachment )  {
      $src = wp_get_attachment_image_src($id, $size);
      $zoom = wp_get_attachment_image_src($id, $zoomsize);
      $link = get_attachment_link($id);
      $title = $attachment->post_title;
      $caption = $attachment->post_excerpt;
      $description = $attachment->post_content;
      $ratio = 'regular';

      if ($src[1] == '1024'){
        $ratio = 'landscape';
      }
      if ($src[2] == '1024'){
        $ratio = 'portrait';
      }

      $itemtag = 'li id="image_'.$id.'" class="'.$ratio.'"';

      if ($caption=='') {
        $imagetag = '<figure><img src="'.$src[0].'" alt="'.$title.'" /></figure>';
      }else {
        $imagetag = '<figure><img src="'.$src[0].'" alt="'.$title.'" /><figcaption>'.$caption.'</figcaption></figure>';
      }

      $output .= "<$itemtag>";
      $output .= "\n\t\t\t";
      $output .= "$imagetag";
      $output .= "\n\t\t";
      $output .= "</$itemtag>";
      $output .= "\n\t\t";
    }
    $output .= "</ul>";
    return $output;
  }
add_shortcode('gallery', 'simplier_gallery');

?>