WordPress: Custom Widget

wp-custom-widget.php

add_action('widgets_init', 'create_arbitrary_sidebar');
function create_arbitrary_sidebar(){
  register_sidebar(array(
    'name' => __('Shortcode Widgets'),
    'id' => 'arbitrary',
    'description' => sprintf(__('Widgets aus diesem Bereich lassen sich über Shortcodes %1$s oder %2$s in Beiträge/Seiten einfügen.'), '[widget ID]', '[widget Name]'),
    'before_widget' => '<div class="block"><div class="block-content block-%2$s clear-block" id="instance-%1$s">',
    'after_widget' => '</div></div>',
    'before_title' => '<h3 class="title">',
    'after_title' => '</h3>'
   ));
}

add_action('in_widget_form', 'widget_shortcodes_info', 10, 3);
function widget_shortcodes_info($widget, $return, $instance){
  if(!is_numeric($widget->number)) return; // wp-save bug :( widget needs to be saved first...

  global $wp_registered_widgets;

  // get the active widgets from all sidebars
  $sidebars_widgets = wp_get_sidebars_widgets();

  // prepare matches
  $matches = array();
  foreach($wp_registered_widgets as $i => $w)
    if($w['name'] == $widget->name) $matches[] = $w['id'];

  // find out the widget position (number)
  $number = 0;
  $is_arbitrary = false;
  if(!empty($sidebars_widgets['arbitrary']))
    foreach($sidebars_widgets['arbitrary'] as $i => $value):
      if(in_array($value, $matches) && !$is_arbitrary) $number = $number +1;
      if($value == $widget->id) $is_arbitrary = true;
    endforeach;

  echo '<div style="background:#f2f2f2; padding: 12px;"><b style="display: block; margin-bottom: 5px;">Shortcodes</b>';
  echo '<code>[widget '.substr(md5($widget->id), 0, 8).']</code><br />
  		<code>[widget "'.$widget->name.'"'.(($number > 1) ? ' number='.$number : null).']</code>
  		</div>';
}

add_shortcode('widget', 'shortcode_widget');
function shortcode_widget($atts){
  global $wp_registered_widgets, $wp_registered_sidebars;
  extract(shortcode_atts(array(
    'number' => false,        // only taken in consideration if the 1st argument is the "Widget Name" (not the hashed ID)
    'title' => true,          // show titles?
    'area' => 'arbitrary'     // sidebar to search
  ), $atts));

  // get 1st parameter (assuming this is the target widget id or name)
  if (!empty($atts[0])) $widget = esc_attr($atts[0]); else return;

  $sidebar = esc_attr($area);
  $number = intval($number);

  $callback = false;
  $possible_matches = array();
  $sidebars_widgets = wp_get_sidebars_widgets();
  if((empty($sidebars_widgets[$sidebar]) || empty($wp_registered_widgets)) && (current_user_can('edit_themes')))
    return "no valid active widgets in {$sidebar}";

  // assuming we get the md5 hashed ID
  foreach ($wp_registered_widgets as $i => $w)
    if ($widget == substr(md5($w['id']), 0, 8)):
      $callback = ($w['callback']);
      $widget = $w['id']; // real widget ID

    // compare widget names as well, and build a array with the possible widget matches array
    // (which is used later if ID match fails)
    elseif($widget == $w['name']):
      $possible_matches[] = $w['id'];

    endif;

  // nothing found, assume it's the "Widget Name".
  if(!$callback):
    $valid_matches = array();
    foreach($sidebars_widgets[$sidebar] as $i => $w)
      foreach($possible_matches as $id) if($id == $w) $valid_matches[] = $w;

    if(!empty($valid_matches)) $widget = $number ? $valid_matches[$number-1] : $widget = $valid_matches[0];
    if($widget && isset($wp_registered_widgets[$widget]['callback'])) $callback = $wp_registered_widgets[$widget]['callback'];
  endif;

  // yey. we found it
  if($callback):
    ob_start();

    $params = array_merge(array(array_merge($wp_registered_sidebars[$sidebar], array('widget_id' => $widget, 'widget_name' => $wp_registered_widgets[$widget]['name']))), (array)$wp_registered_widgets[$widget]['params']);

    $classname_ = '';
    foreach ((array)$wp_registered_widgets[$widget]['classname'] as $cn)
      if (is_string($cn)) $classname_ .= '_'.$cn; elseif (is_object($cn)) $classname_ .= '_'.get_class($cn);
    $classname_ = ltrim($classname_, '_');
    $params[0]['before_widget'] = sprintf($params[0]['before_widget'], $widget, $classname_);
    $params = apply_filters('dynamic_sidebar_params', $params);

    if (is_callable($callback)) call_user_func_array($callback, $params);
    $output = ob_get_clean();

    // remove h3 if title = false
    if(!$title) $output = preg_replace('#<h3 class="title">(.*?)</h3>#', '', $output);
    return $output;
  else:
   return "widget instance not found: ".esc_attr($atts[0]);
  endif;
}