WP_Widget_Text

functions.php

<?php
/**
* HTML widget class
*
* WPINC/default-widgets.php内にある
* WP_Widget_Textを使いやすいように改変したもの
*
*/
class WP_Widget_HTML extends WP_Widget {

  function WP_Widget_HTML() {
    $widget_ops = array('classname' => 'widget_html', 'description' => '入力したHTMLを出力する');
    $control_ops = array('width' => 400, 'height' => 350);
    $this->WP_Widget('html', __('HTML'), $widget_ops, $control_ops);
  }

  function widget( $args, $instance ) {
    add_filter('widget_html', 'do_shortcode');
    extract($args);
    $html = apply_filters('widget_html', $instance['html'], $instance );
    echo $before_widget;
    echo $html;
    echo $after_widget;
  }

  function update( $new_instance, $old_instance ) {
    $instance = $old_instance;
    if ( current_user_can('unfiltered_html') )
      $instance['html'] = $new_instance['html'];
    else
      $instance['html'] = stripslashes( wp_filter_post_kses( addslashes($new_instance['html']) ) ); // wp_filter_post_kses() expects slashed
      return $instance;
  }

  function form( $instance ) {
    $instance = wp_parse_args( (array) $instance, array( 'html' => '' ) );
    $html = format_to_edit($instance['html']);
?>
<textarea class="widefat" rows="16" cols="20" id="<?php echo $this->get_field_id('html'); ?>" name="<?php echo $this->get_field_name('html'); ?>"><?php echo $html; ?></textarea>
<?php
  }
}
register_widget('WP_Widget_HTML');