WordPress 4.3-scripts
[autoinstalls/wordpress.git] / wp-includes / class-wp-customize-widgets.php
index 40663f29379c575ae1d489098bb1a7045d66ca49..8569228e4670eafd9d92a16bb86b30cf0bd30ef7 100644 (file)
@@ -1,13 +1,21 @@
 <?php
 /**
- * Customize Widgets Class
- *
- * Implements widget management in the Customizer.
+ * WordPress Customize Widgets classes
  *
  * @package WordPress
  * @subpackage Customize
  * @since 3.9.0
  */
+
+/**
+ * Customize Widgets class.
+ *
+ * Implements widget management in the Customizer.
+ *
+ * @since 3.9.0
+ *
+ * @see WP_Customize_Manager
+ */
 final class WP_Customize_Widgets {
 
        /**
@@ -32,40 +40,38 @@ final class WP_Customize_Widgets {
                'rss', 'search', 'tag_cloud', 'text',
        );
 
-       /**
-        * @since 3.9.0
-        * @access protected
-        * @var
-        */
-       protected $_customized;
-
        /**
         * @since 3.9.0
         * @access protected
         * @var array
         */
-       protected $_prepreview_added_filters = array();
+       protected $rendered_sidebars = array();
 
        /**
         * @since 3.9.0
         * @access protected
         * @var array
         */
-       protected $rendered_sidebars = array();
+       protected $rendered_widgets = array();
 
        /**
         * @since 3.9.0
         * @access protected
         * @var array
         */
-       protected $rendered_widgets = array();
+       protected $old_sidebars_widgets = array();
 
        /**
-        * @since 3.9.0
+        * Mapping of setting type to setting ID pattern.
+        *
+        * @since 4.2.0
         * @access protected
         * @var array
         */
-       protected $old_sidebars_widgets = array();
+       protected $setting_id_patterns = array(
+               'widget_instance' => '/^(widget_.+?)(?:\[(\d+)\])?$/',
+               'sidebar_widgets' => '/^sidebars_widgets\[(.+?)\]$/',
+       );
 
        /**
         * Initial loader.
@@ -78,7 +84,8 @@ final class WP_Customize_Widgets {
        public function __construct( $manager ) {
                $this->manager = $manager;
 
-               add_action( 'after_setup_theme',                       array( $this, 'setup_widget_addition_previews' ) );
+               add_filter( 'customize_dynamic_setting_args',          array( $this, 'filter_customize_dynamic_setting_args' ), 10, 2 );
+               add_action( 'after_setup_theme',                       array( $this, 'register_settings' ) );
                add_action( 'wp_loaded',                               array( $this, 'override_sidebars_widgets_for_theme_switch' ) );
                add_action( 'customize_controls_init',                 array( $this, 'customize_controls_init' ) );
                add_action( 'customize_register',                      array( $this, 'schedule_customize_register' ), 1 );
@@ -88,6 +95,7 @@ final class WP_Customize_Widgets {
                add_action( 'customize_controls_print_footer_scripts', array( $this, 'print_footer_scripts' ) );
                add_action( 'customize_controls_print_footer_scripts', array( $this, 'output_widget_control_templates' ) );
                add_action( 'customize_preview_init',                  array( $this, 'customize_preview_init' ) );
+               add_filter( 'customize_refresh_nonces',                array( $this, 'refresh_nonces' ) );
 
                add_action( 'dynamic_sidebar',                         array( $this, 'tally_rendered_widgets' ) );
                add_filter( 'is_active_sidebar',                       array( $this, 'tally_sidebars_via_is_active_sidebar_calls' ), 10, 2 );
@@ -95,199 +103,101 @@ final class WP_Customize_Widgets {
        }
 
        /**
-        * Get an unslashed post value or return a default.
-        *
-        * @since 3.9.0
+        * Get the widget setting type given a setting ID.
         *
+        * @since 4.2.0
         * @access protected
         *
-        * @param string $name    Post value.
-        * @param mixed  $default Default post value.
-        * @return mixed Unslashed post value or default value.
+        * @staticvar array $cache
+        *
+        * @param $setting_id Setting ID.
+        * @return string|void Setting type.
         */
-       protected function get_post_value( $name, $default = null ) {
-               if ( ! isset( $_POST[ $name ] ) ) {
-                       return $default;
+       protected function get_setting_type( $setting_id ) {
+               static $cache = array();
+               if ( isset( $cache[ $setting_id ] ) ) {
+                       return $cache[ $setting_id ];
+               }
+               foreach ( $this->setting_id_patterns as $type => $pattern ) {
+                       if ( preg_match( $pattern, $setting_id ) ) {
+                               $cache[ $setting_id ] = $type;
+                               return $type;
+                       }
                }
-
-               return wp_unslash( $_POST[$name] );
        }
 
        /**
-        * Set up widget addition previews.
-        *
-        * Since the widgets get registered on 'widgets_init' before the customizer
-        * settings are set up on 'customize_register', we have to filter the options
-        * similarly to how the setting previewer will filter the options later.
-        *
-        * @since 3.9.0
+        * Inspect the incoming customized data for any widget settings, and dynamically add them up-front so widgets will be initialized properly.
         *
+        * @since 4.2.0
         * @access public
         */
-       public function setup_widget_addition_previews() {
-               $is_customize_preview = false;
-
-               if ( ! empty( $this->manager ) && ! is_admin() && 'on' === $this->get_post_value( 'wp_customize' ) ) {
-                       $is_customize_preview = check_ajax_referer( 'preview-customize_' . $this->manager->get_stylesheet(), 'nonce', false );
-               }
-
-               $is_ajax_widget_update = false;
-               if ( $this->manager->doing_ajax() && 'update-widget' === $this->get_post_value( 'action' ) ) {
-                       $is_ajax_widget_update = check_ajax_referer( 'update-widget', 'nonce', false );
-               }
-
-               $is_ajax_customize_save = false;
-               if ( $this->manager->doing_ajax() && 'customize_save' === $this->get_post_value( 'action' ) ) {
-                       $is_ajax_customize_save = check_ajax_referer( 'save-customize_' . $this->manager->get_stylesheet(), 'nonce', false );
-               }
-
-               $is_valid_request = ( $is_ajax_widget_update || $is_customize_preview || $is_ajax_customize_save );
-               if ( ! $is_valid_request ) {
-                       return;
-               }
-
-               // Input from customizer preview.
-               if ( isset( $_POST['customized'] ) ) {
-                       $this->_customized = json_decode( $this->get_post_value( 'customized' ), true );
-               } else { // Input from ajax widget update request.
-                       $this->_customized = array();
-                       $id_base = $this->get_post_value( 'id_base' );
-                       $widget_number = $this->get_post_value( 'widget_number', false );
-                       $option_name = 'widget_' . $id_base;
-                       $this->_customized[ $option_name ] = array();
-                       if ( preg_match( '/^[0-9]+$/', $widget_number ) ) {
-                               $option_name .= '[' . $widget_number . ']';
-                               $this->_customized[ $option_name ][ $widget_number ] = array();
+       public function register_settings() {
+               $widget_setting_ids = array();
+               $incoming_setting_ids = array_keys( $this->manager->unsanitized_post_values() );
+               foreach ( $incoming_setting_ids as $setting_id ) {
+                       if ( ! is_null( $this->get_setting_type( $setting_id ) ) ) {
+                               $widget_setting_ids[] = $setting_id;
                        }
                }
+               if ( $this->manager->doing_ajax( 'update-widget' ) && isset( $_REQUEST['widget-id'] ) ) {
+                       $widget_setting_ids[] = $this->get_setting_id( wp_unslash( $_REQUEST['widget-id'] ) );
+               }
 
-               $function = array( $this, 'prepreview_added_sidebars_widgets' );
-
-               $hook = 'option_sidebars_widgets';
-               add_filter( $hook, $function );
-               $this->_prepreview_added_filters[] = compact( 'hook', 'function' );
-
-               $hook = 'default_option_sidebars_widgets';
-               add_filter( $hook, $function );
-               $this->_prepreview_added_filters[] = compact( 'hook', 'function' );
-
-               $function = array( $this, 'prepreview_added_widget_instance' );
-               foreach ( $this->_customized as $setting_id => $value ) {
-                       if ( preg_match( '/^(widget_.+?)(?:\[(\d+)\])?$/', $setting_id, $matches ) ) {
-                               $option = $matches[1];
-
-                               $hook = sprintf( 'option_%s', $option );
-                               if ( ! has_filter( $hook, $function ) ) {
-                                       add_filter( $hook, $function );
-                                       $this->_prepreview_added_filters[] = compact( 'hook', 'function' );
-                               }
-
-                               $hook = sprintf( 'default_option_%s', $option );
-                               if ( ! has_filter( $hook, $function ) ) {
-                                       add_filter( $hook, $function );
-                                       $this->_prepreview_added_filters[] = compact( 'hook', 'function' );
-                               }
+               $settings = $this->manager->add_dynamic_settings( array_unique( $widget_setting_ids ) );
 
-                               /*
-                                * Make sure the option is registered so that the update_option()
-                                * won't fail due to the filters providing a default value, which
-                                * causes the update_option() to get confused.
-                                */
-                               add_option( $option, array() );
+               /*
+                * Preview settings right away so that widgets and sidebars will get registered properly.
+                * But don't do this if a customize_save because this will cause WP to think there is nothing
+                * changed that needs to be saved.
+                */
+               if ( ! $this->manager->doing_ajax( 'customize_save' ) ) {
+                       foreach ( $settings as $setting ) {
+                               $setting->preview();
                        }
                }
        }
 
        /**
-        * Ensure that newly-added widgets will appear in the widgets_sidebars.
-        *
-        * This is necessary because the customizer's setting preview filters
-        * are added after the widgets_init action, which is too late for the
-        * widgets to be set up properly.
+        * Determine the arguments for a dynamically-created setting.
         *
-        * @since 3.9.0
+        * @since 4.2.0
         * @access public
         *
-        * @param array $sidebars_widgets Associative array of sidebars and their widgets.
-        * @return array Filtered array of sidebars and their widgets.
+        * @param false|array $setting_args The arguments to the WP_Customize_Setting constructor.
+        * @param string      $setting_id   ID for dynamic setting, usually coming from `$_POST['customized']`.
+        * @return false|array Setting arguments, false otherwise.
         */
-       public function prepreview_added_sidebars_widgets( $sidebars_widgets ) {
-               foreach ( $this->_customized as $setting_id => $value ) {
-                       if ( preg_match( '/^sidebars_widgets\[(.+?)\]$/', $setting_id, $matches ) ) {
-                               $sidebar_id = $matches[1];
-                               $sidebars_widgets[ $sidebar_id ] = $value;
-                       }
+       public function filter_customize_dynamic_setting_args( $args, $setting_id ) {
+               if ( $this->get_setting_type( $setting_id ) ) {
+                       $args = $this->get_setting_args( $setting_id );
                }
-               return $sidebars_widgets;
+               return $args;
        }
 
        /**
-        * Ensure newly-added widgets have empty instances so they
-        * will be recognized.
-        *
-        * This is necessary because the customizer's setting preview
-        * filters are added after the widgets_init action, which is
-        * too late for the widgets to be set up properly.
+        * Get an unslashed post value or return a default.
         *
         * @since 3.9.0
-        * @access public
         *
-        * @param array|bool|mixed $value Widget instance(s), false if open was empty.
-        * @return array|mixed Widget instance(s) with additions.
-        */
-       public function prepreview_added_widget_instance( $value = false ) {
-               if ( ! preg_match( '/^(?:default_)?option_(widget_(.+))/', current_filter(), $matches ) ) {
-                       return $value;
-               }
-               $id_base = $matches[2];
-
-               foreach ( $this->_customized as $setting_id => $setting ) {
-                       $parsed_setting_id = $this->parse_widget_setting_id( $setting_id );
-                       if ( is_wp_error( $parsed_setting_id ) || $id_base !== $parsed_setting_id['id_base'] ) {
-                               continue;
-                       }
-                       $widget_number = $parsed_setting_id['number'];
-
-                       if ( is_null( $widget_number ) ) {
-                               // Single widget.
-                               if ( false === $value ) {
-                                       $value = array();
-                               }
-                       } else {
-                               // Multi widget.
-                               if ( empty( $value ) ) {
-                                       $value = array( '_multiwidget' => 1 );
-                               }
-                               if ( ! isset( $value[ $widget_number ] ) ) {
-                                       $value[ $widget_number ] = array();
-                               }
-                       }
-               }
-
-               return $value;
-       }
-
-       /**
-        * Remove pre-preview filters.
-        *
-        * Removes filters added in setup_widget_addition_previews()
-        * to ensure widgets are populating the options during
-        * 'widgets_init'.
+        * @access protected
         *
-        * @since 3.9.0
-        * @access public
+        * @param string $name    Post value.
+        * @param mixed  $default Default post value.
+        * @return mixed Unslashed post value or default value.
         */
-       public function remove_prepreview_filters() {
-               foreach ( $this->_prepreview_added_filters as $prepreview_added_filter ) {
-                       remove_filter( $prepreview_added_filter['hook'], $prepreview_added_filter['function'] );
+       protected function get_post_value( $name, $default = null ) {
+               if ( ! isset( $_POST[ $name ] ) ) {
+                       return $default;
                }
-               $this->_prepreview_added_filters = array();
+
+               return wp_unslash( $_POST[ $name ] );
        }
 
        /**
         * Override sidebars_widgets for theme switch.
         *
-        * When switching a theme via the customizer, supply any previously-configured
+        * When switching a theme via the Customizer, supply any previously-configured
         * sidebars_widgets from the target theme as the initial sidebars_widgets
         * setting. Also store the old theme's existing settings so that they can
         * be passed along for storing in the sidebars_widgets theme_mod when the
@@ -295,6 +205,9 @@ final class WP_Customize_Widgets {
         *
         * @since 3.9.0
         * @access public
+        *
+        * @global array $sidebars_widgets
+        * @global array $_wp_sidebars_widgets
         */
        public function override_sidebars_widgets_for_theme_switch() {
                global $sidebars_widgets;
@@ -310,10 +223,12 @@ final class WP_Customize_Widgets {
                $sidebars_widgets = $this->old_sidebars_widgets;
                $sidebars_widgets = retrieve_widgets( 'customize' );
                add_filter( 'option_sidebars_widgets', array( $this, 'filter_option_sidebars_widgets_for_theme_switch' ), 1 );
+               // reset global cache var used by wp_get_sidebars_widgets()
+               unset( $GLOBALS['_wp_sidebars_widgets'] );
        }
 
        /**
-        * Filter old_sidebars_widgets_data customizer setting.
+        * Filter old_sidebars_widgets_data Customizer setting.
         *
         * When switching themes, filter the Customizer setting
         * old_sidebars_widgets_data to supply initial $sidebars_widgets before they
@@ -325,7 +240,8 @@ final class WP_Customize_Widgets {
         * @since 3.9.0
         * @access public
         *
-        * @param array $sidebars_widgets
+        * @param array $old_sidebars_widgets
+        * @return array
         */
        public function filter_customize_value_old_sidebars_widgets_data( $old_sidebars_widgets ) {
                return $this->old_sidebars_widgets;
@@ -342,7 +258,10 @@ final class WP_Customize_Widgets {
         * @since 3.9.0
         * @access public
         *
+        * @global array $sidebars_widgets
+        *
         * @param array $sidebars_widgets
+        * @return array
         */
        public function filter_option_sidebars_widgets_for_theme_switch( $sidebars_widgets ) {
                $sidebars_widgets = $GLOBALS['sidebars_widgets'];
@@ -380,7 +299,7 @@ final class WP_Customize_Widgets {
         * @access public
         */
        public function schedule_customize_register() {
-               if ( is_admin() ) { // @todo for some reason, $wp_customize->is_preview() is true here?
+               if ( is_admin() ) {
                        $this->customize_register();
                } else {
                        add_action( 'wp', array( $this, 'customize_register' ) );
@@ -388,17 +307,21 @@ final class WP_Customize_Widgets {
        }
 
        /**
-        * Register customizer settings and controls for all sidebars and widgets.
+        * Register Customizer settings and controls for all sidebars and widgets.
         *
         * @since 3.9.0
         * @access public
+        *
+        * @global array $wp_registered_widgets
+        * @global array $wp_registered_widget_controls
+        * @global array $wp_registered_sidebars
         */
        public function customize_register() {
                global $wp_registered_widgets, $wp_registered_widget_controls, $wp_registered_sidebars;
 
                $sidebars_widgets = array_merge(
                        array( 'wp_inactive_widgets' => array() ),
-                       array_fill_keys( array_keys( $GLOBALS['wp_registered_sidebars'] ), array() ),
+                       array_fill_keys( array_keys( $wp_registered_sidebars ), array() ),
                        wp_get_sidebars_widgets()
                );
 
@@ -412,12 +335,9 @@ final class WP_Customize_Widgets {
                foreach ( array_keys( $wp_registered_widgets ) as $widget_id ) {
                        $setting_id   = $this->get_setting_id( $widget_id );
                        $setting_args = $this->get_setting_args( $setting_id );
-
-                       $setting_args['sanitize_callback']    = array( $this, 'sanitize_widget_instance' );
-                       $setting_args['sanitize_js_callback'] = array( $this, 'sanitize_widget_js_instance' );
-
-                       $this->manager->add_setting( $setting_id, $setting_args );
-
+                       if ( ! $this->manager->get_setting( $setting_id ) ) {
+                               $this->manager->add_setting( $setting_id, $setting_args );
+                       }
                        $new_setting_ids[] = $setting_id;
                }
 
@@ -429,16 +349,23 @@ final class WP_Customize_Widgets {
                        $setting_id = 'old_sidebars_widgets_data';
                        $setting_args = $this->get_setting_args( $setting_id, array(
                                'type' => 'global_variable',
+                               'dirty' => true,
                        ) );
                        $this->manager->add_setting( $setting_id, $setting_args );
                }
 
+               $this->manager->add_panel( 'widgets', array(
+                       'title'       => __( 'Widgets' ),
+                       'description' => __( 'Widgets are independent sections of content that can be placed into widgetized areas provided by your theme (commonly called sidebars).' ),
+                       'priority'    => 110,
+               ) );
+
                foreach ( $sidebars_widgets as $sidebar_id => $sidebar_widget_ids ) {
                        if ( empty( $sidebar_widget_ids ) ) {
                                $sidebar_widget_ids = array();
                        }
 
-                       $is_registered_sidebar = isset( $GLOBALS['wp_registered_sidebars'][$sidebar_id] );
+                       $is_registered_sidebar = isset( $wp_registered_sidebars[ $sidebar_id ] );
                        $is_inactive_widgets   = ( 'wp_inactive_widgets' === $sidebar_id );
                        $is_active_sidebar     = ( $is_registered_sidebar && ! $is_inactive_widgets );
 
@@ -446,11 +373,12 @@ final class WP_Customize_Widgets {
                        if ( $is_registered_sidebar || $is_inactive_widgets ) {
                                $setting_id   = sprintf( 'sidebars_widgets[%s]', $sidebar_id );
                                $setting_args = $this->get_setting_args( $setting_id );
-
-                               $setting_args['sanitize_callback']    = array( $this, 'sanitize_sidebar_widgets' );
-                               $setting_args['sanitize_js_callback'] = array( $this, 'sanitize_sidebar_widgets_js_instance' );
-
-                               $this->manager->add_setting( $setting_id, $setting_args );
+                               if ( ! $this->manager->get_setting( $setting_id ) ) {
+                                       if ( ! $this->manager->is_theme_active() ) {
+                                               $setting_args['dirty'] = true;
+                                       }
+                                       $this->manager->add_setting( $setting_id, $setting_args );
+                               }
                                $new_setting_ids[] = $setting_id;
 
                                // Add section to contain controls.
@@ -458,10 +386,11 @@ final class WP_Customize_Widgets {
                                if ( $is_active_sidebar ) {
 
                                        $section_args = array(
-                                               /* translators: %s: sidebar name */
-                                               'title' => sprintf( __( 'Widgets: %s' ), $GLOBALS['wp_registered_sidebars'][$sidebar_id]['name'] ),
-                                               'description' => $GLOBALS['wp_registered_sidebars'][$sidebar_id]['description'],
-                                               'priority' => 1000 + array_search( $sidebar_id, array_keys( $wp_registered_sidebars ) ),
+                                               'title' => $wp_registered_sidebars[ $sidebar_id ]['name'],
+                                               'description' => $wp_registered_sidebars[ $sidebar_id ]['description'],
+                                               'priority' => array_search( $sidebar_id, array_keys( $wp_registered_sidebars ) ),
+                                               'panel' => 'widgets',
+                                               'sidebar_id' => $sidebar_id,
                                        );
 
                                        /**
@@ -475,7 +404,8 @@ final class WP_Customize_Widgets {
                                         */
                                        $section_args = apply_filters( 'customizer_widgets_section_args', $section_args, $section_id, $sidebar_id );
 
-                                       $this->manager->add_section( $section_id, $section_args );
+                                       $section = new WP_Customize_Sidebar_Section( $this->manager, $section_id, $section_args );
+                                       $this->manager->add_section( $section );
 
                                        $control = new WP_Widget_Area_Customize_Control( $this->manager, $setting_id, array(
                                                'section'    => $section_id,
@@ -492,13 +422,13 @@ final class WP_Customize_Widgets {
                        foreach ( $sidebar_widget_ids as $i => $widget_id ) {
 
                                // Skip widgets that may have gone away due to a plugin being deactivated.
-                               if ( ! $is_active_sidebar || ! isset( $GLOBALS['wp_registered_widgets'][$widget_id] ) ) {
+                               if ( ! $is_active_sidebar || ! isset( $wp_registered_widgets[$widget_id] ) ) {
                                        continue;
                                }
 
-                               $registered_widget = $GLOBALS['wp_registered_widgets'][$widget_id];
+                               $registered_widget = $wp_registered_widgets[$widget_id];
                                $setting_id        = $this->get_setting_id( $widget_id );
-                               $id_base           = $GLOBALS['wp_registered_widget_controls'][$widget_id]['id_base'];
+                               $id_base           = $wp_registered_widget_controls[$widget_id]['id_base'];
 
                                $control = new WP_Widget_Form_Customize_Control( $this->manager, $setting_id, array(
                                        'label'          => $registered_widget['name'],
@@ -515,20 +445,17 @@ final class WP_Customize_Widgets {
                        }
                }
 
-               /*
-                * We have to register these settings later than customize_preview_init
-                * so that other filters have had a chance to run.
-                */
-               if ( did_action( 'customize_preview_init' ) ) {
+               if ( ! $this->manager->doing_ajax( 'customize_save' ) ) {
                        foreach ( $new_setting_ids as $new_setting_id ) {
                                $this->manager->get_setting( $new_setting_id )->preview();
                        }
                }
-               $this->remove_prepreview_filters();
+
+               add_filter( 'sidebars_widgets', array( $this, 'preview_sidebars_widgets' ), 1 );
        }
 
        /**
-        * Covert a widget_id into its corresponding customizer setting ID (option name).
+        * Covert a widget_id into its corresponding Customizer setting ID (option name).
         *
         * @since 3.9.0
         * @access public
@@ -550,15 +477,17 @@ final class WP_Customize_Widgets {
         * Determine whether the widget is considered "wide".
         *
         * Core widgets which may have controls wider than 250, but can
-        * still be shown in the narrow customizer panel. The RSS and Text
+        * still be shown in the narrow Customizer panel. The RSS and Text
         * widgets in Core, for example, have widths of 400 and yet they
-        * still render fine in the customizer panel. This method will
+        * still render fine in the Customizer panel. This method will
         * return all Core widgets as being not wide, but this can be
         * overridden with the is_wide_widget_in_customizer filter.
         *
         * @since 3.9.0
         * @access public
         *
+        * @global $wp_registered_widget_controls
+        *
         * @param string $widget_id Widget ID.
         * @return bool Whether or not the widget is a "wide" widget.
         */
@@ -658,12 +587,18 @@ final class WP_Customize_Widgets {
        }
 
        /**
-        * Enqueue scripts and styles for customizer panel and export data to JavaScript.
+        * Enqueue scripts and styles for Customizer panel and export data to JavaScript.
         *
         * @since 3.9.0
         * @access public
+        *
+        * @global WP_Scripts $wp_scripts
+        * @global array $wp_registered_sidebars
+        * @global array $wp_registered_widgets
         */
        public function enqueue_scripts() {
+               global $wp_scripts, $wp_registered_sidebars, $wp_registered_widgets;
+
                wp_enqueue_style( 'customize-widgets' );
                wp_enqueue_script( 'customize-widgets' );
 
@@ -707,12 +642,10 @@ final class WP_Customize_Widgets {
                        </div>'
                );
 
-               global $wp_scripts;
-
                $settings = array(
                        'nonce'                => wp_create_nonce( 'update-widget' ),
-                       'registeredSidebars'   => array_values( $GLOBALS['wp_registered_sidebars'] ),
-                       'registeredWidgets'    => $GLOBALS['wp_registered_widgets'],
+                       'registeredSidebars'   => array_values( $wp_registered_sidebars ),
+                       'registeredWidgets'    => $wp_registered_widgets,
                        'availableWidgets'     => $available_widgets, // @todo Merge this with registered_widgets
                        'l10n' => array(
                                'saveBtnLabel'     => __( 'Apply' ),
@@ -720,6 +653,8 @@ final class WP_Customize_Widgets {
                                'removeBtnLabel'   => __( 'Remove' ),
                                'removeBtnTooltip' => __( 'Trash widget by moving it to the inactive widgets sidebar.' ),
                                'error'            => __( 'An error has occurred. Please reload the page and try again.' ),
+                               'widgetMovedUp'    => __( 'Widget moved up' ),
+                               'widgetMovedDown'  => __( 'Widget moved down' ),
                        ),
                        'tpl' => array(
                                'widgetReorderNav' => $widget_reorder_nav_tpl,
@@ -734,7 +669,7 @@ final class WP_Customize_Widgets {
                $wp_scripts->add_data(
                        'customize-widgets',
                        'data',
-                       sprintf( 'var _wpCustomizeWidgetsSettings = %s;', json_encode( $settings ) )
+                       sprintf( 'var _wpCustomizeWidgetsSettings = %s;', wp_json_encode( $settings ) )
                );
        }
 
@@ -748,15 +683,29 @@ final class WP_Customize_Widgets {
                ?>
                <div id="widgets-left"><!-- compatibility with JS which looks for widget templates here -->
                <div id="available-widgets">
+                       <div class="customize-section-title">
+                               <button class="customize-section-back" tabindex="-1">
+                                       <span class="screen-reader-text"><?php _e( 'Back' ); ?></span>
+                               </button>
+                               <h3>
+                                       <span class="customize-action"><?php
+                                               /* translators: &#9656; is the unicode right-pointing triangle, and %s is the section title in the Customizer */
+                                               echo sprintf( __( 'Customizing &#9656; %s' ), esc_html( $this->manager->get_panel( 'widgets' )->title ) );
+                                       ?></span>
+                                       <?php _e( 'Add a Widget' ); ?>
+                               </h3>
+                       </div>
                        <div id="available-widgets-filter">
                                <label class="screen-reader-text" for="widgets-search"><?php _e( 'Search Widgets' ); ?></label>
                                <input type="search" id="widgets-search" placeholder="<?php esc_attr_e( 'Search widgets&hellip;' ) ?>" />
                        </div>
+                       <div id="available-widgets-list">
                        <?php foreach ( $this->get_available_widgets() as $available_widget ): ?>
                                <div id="widget-tpl-<?php echo esc_attr( $available_widget['id'] ) ?>" data-widget-id="<?php echo esc_attr( $available_widget['id'] ) ?>" class="widget-tpl <?php echo esc_attr( $available_widget['id'] ) ?>" tabindex="0">
                                        <?php echo $available_widget['control_tpl']; ?>
                                </div>
                        <?php endforeach; ?>
+                       </div><!-- #available-widgets-list -->
                </div><!-- #available-widgets -->
                </div><!-- #widgets-left -->
                <?php
@@ -794,6 +743,15 @@ final class WP_Customize_Widgets {
                        'transport'  => 'refresh',
                        'default'    => array(),
                );
+
+               if ( preg_match( $this->setting_id_patterns['sidebar_widgets'], $id, $matches ) ) {
+                       $args['sanitize_callback'] = array( $this, 'sanitize_sidebar_widgets' );
+                       $args['sanitize_js_callback'] = array( $this, 'sanitize_sidebar_widgets_js_instance' );
+               } elseif ( preg_match( $this->setting_id_patterns['widget_instance'], $id, $matches ) ) {
+                       $args['sanitize_callback'] = array( $this, 'sanitize_widget_instance' );
+                       $args['sanitize_js_callback'] = array( $this, 'sanitize_widget_js_instance' );
+               }
+
                $args = array_merge( $args, $overrides );
 
                /**
@@ -821,15 +779,10 @@ final class WP_Customize_Widgets {
         * @return array Array of sanitized widget IDs.
         */
        public function sanitize_sidebar_widgets( $widget_ids ) {
-               global $wp_registered_widgets;
-
-               $widget_ids           = array_map( 'strval', (array) $widget_ids );
+               $widget_ids = array_map( 'strval', (array) $widget_ids );
                $sanitized_widget_ids = array();
-
                foreach ( $widget_ids as $widget_id ) {
-                       if ( array_key_exists( $widget_id, $wp_registered_widgets ) ) {
-                               $sanitized_widget_ids[] = $widget_id;
-                       }
+                       $sanitized_widget_ids[] = preg_replace( '/[^a-z0-9_\-]/', '', $widget_id );
                }
                return $sanitized_widget_ids;
        }
@@ -840,6 +793,10 @@ final class WP_Customize_Widgets {
         * @since 3.9.0
         * @access public
         *
+        * @global array $wp_registered_widgets
+        * @global array $wp_registered_widget_controls
+        * @staticvar array $available_widgets
+        *
         * @see wp_list_widgets()
         *
         * @return array List of available widgets.
@@ -921,7 +878,6 @@ final class WP_Customize_Widgets {
         * Naturally order available widgets by name.
         *
         * @since 3.9.0
-        * @static
         * @access protected
         *
         * @param array $widget_a The first widget to compare.
@@ -946,7 +902,7 @@ final class WP_Customize_Widgets {
 
                call_user_func_array( 'wp_widget_control', $args );
                $replacements = array(
-                       '<form action="" method="post">' => '<div class="form">',
+                       '<form method="post">' => '<div class="form">',
                        '</form>' => '</div><!-- .form -->',
                );
 
@@ -958,31 +914,45 @@ final class WP_Customize_Widgets {
        }
 
        /**
-        * Add hooks for the customizer preview.
+        * Add hooks for the Customizer preview.
         *
         * @since 3.9.0
         * @access public
         */
        public function customize_preview_init() {
-               add_filter( 'sidebars_widgets',   array( $this, 'preview_sidebars_widgets' ), 1 );
                add_action( 'wp_enqueue_scripts', array( $this, 'customize_preview_enqueue' ) );
                add_action( 'wp_print_styles',    array( $this, 'print_preview_css' ), 1 );
                add_action( 'wp_footer',          array( $this, 'export_preview_data' ), 20 );
        }
 
+       /**
+        * Refresh nonce for widget updates.
+        *
+        * @since 4.2.0
+        * @access public
+        *
+        * @param  array $nonces Array of nonces.
+        * @return array $nonces Array of nonces.
+        */
+       public function refresh_nonces( $nonces ) {
+               $nonces['update-widget'] = wp_create_nonce( 'update-widget' );
+               return $nonces;
+       }
+
        /**
         * When previewing, make sure the proper previewing widgets are used.
         *
         * Because wp_get_sidebars_widgets() gets called early at init
         * (via wp_convert_widget_settings()) and can set global variable
         * $_wp_sidebars_widgets to the value of get_option( 'sidebars_widgets' )
-        * before the customizer preview filter is added, we have to reset
+        * before the Customizer preview filter is added, we have to reset
         * it after the filter has been added.
         *
         * @since 3.9.0
         * @access public
         *
         * @param array $sidebars_widgets List of widgets for the current sidebar.
+        * @return array
         */
        public function preview_sidebars_widgets( $sidebars_widgets ) {
                $sidebars_widgets = get_option( 'sidebars_widgets' );
@@ -1030,15 +1000,18 @@ final class WP_Customize_Widgets {
         *
         * @since 3.9.0
         * @access public
+     *
+        * @global array $wp_registered_sidebars
+        * @global array $wp_registered_widgets
         */
        public function export_preview_data() {
-
-               // Prepare customizer settings to pass to Javascript.
+               global $wp_registered_sidebars, $wp_registered_widgets;
+               // Prepare Customizer settings to pass to JavaScript.
                $settings = array(
                        'renderedSidebars'   => array_fill_keys( array_unique( $this->rendered_sidebars ), true ),
                        'renderedWidgets'    => array_fill_keys( array_keys( $this->rendered_widgets ), true ),
-                       'registeredSidebars' => array_values( $GLOBALS['wp_registered_sidebars'] ),
-                       'registeredWidgets'  => $GLOBALS['wp_registered_widgets'],
+                       'registeredSidebars' => array_values( $wp_registered_sidebars ),
+                       'registeredWidgets'  => $wp_registered_widgets,
                        'l10n'               => array(
                                'widgetTooltip' => __( 'Shift-click to edit this widget.' ),
                        ),
@@ -1049,7 +1022,7 @@ final class WP_Customize_Widgets {
 
                ?>
                <script type="text/javascript">
-                       var _wpWidgetCustomizerPreviewSettings = <?php echo json_encode( $settings ); ?>;
+                       var _wpWidgetCustomizerPreviewSettings = <?php echo wp_json_encode( $settings ); ?>;
                </script>
                <?php
        }
@@ -1063,7 +1036,33 @@ final class WP_Customize_Widgets {
         * @param array $widget Rendered widget to tally.
         */
        public function tally_rendered_widgets( $widget ) {
-               $this->rendered_widgets[$widget['id']] = true;
+               $this->rendered_widgets[ $widget['id'] ] = true;
+       }
+
+       /**
+        * Determine if a widget is rendered on the page.
+        *
+        * @since 4.0.0
+        * @access public
+        *
+        * @param string $widget_id Widget ID to check.
+        * @return bool Whether the widget is rendered.
+        */
+       public function is_widget_rendered( $widget_id ) {
+               return in_array( $widget_id, $this->rendered_widgets );
+       }
+
+       /**
+        * Determine if a sidebar is rendered on the page.
+        *
+        * @since 4.0.0
+        * @access public
+        *
+        * @param string $sidebar_id Sidebar ID to check.
+        * @return bool Whether the sidebar is rendered.
+        */
+       public function is_sidebar_rendered( $sidebar_id ) {
+               return in_array( $sidebar_id, $this->rendered_sidebars );
        }
 
        /**
@@ -1077,8 +1076,11 @@ final class WP_Customize_Widgets {
         * @since 3.9.0
         * @access public
         *
-        * @param bool    $is_active  Whether the sidebar is active.
-        * @pasram string $sidebar_id Sidebar ID.
+        * @global array $wp_registered_sidebars
+        *
+        * @param bool   $is_active  Whether the sidebar is active.
+        * @param string $sidebar_id Sidebar ID.
+        * @return bool
         */
        public function tally_sidebars_via_is_active_sidebar_calls( $is_active, $sidebar_id ) {
                if ( isset( $GLOBALS['wp_registered_sidebars'][$sidebar_id] ) ) {
@@ -1102,8 +1104,11 @@ final class WP_Customize_Widgets {
         * @since 3.9.0
         * @access public
         *
+        * @global array $wp_registered_sidebars
+        *
         * @param bool   $has_widgets Whether the current sidebar has widgets.
         * @param string $sidebar_id  Sidebar ID.
+        * @return bool
         */
        public function tally_sidebars_via_dynamic_sidebar_calls( $has_widgets, $sidebar_id ) {
                if ( isset( $GLOBALS['wp_registered_sidebars'][$sidebar_id] ) ) {
@@ -1144,7 +1149,7 @@ final class WP_Customize_Widgets {
         * @access public
         *
         * @param array $value Widget instance to sanitize.
-        * @return array Sanitized widget instance.
+        * @return array|void Sanitized widget instance.
         */
        public function sanitize_widget_instance( $value ) {
                if ( $value === array() ) {
@@ -1155,21 +1160,21 @@ final class WP_Customize_Widgets {
                        || empty( $value['instance_hash_key'] )
                        || empty( $value['encoded_serialized_instance'] ) )
                {
-                       return null;
+                       return;
                }
 
                $decoded = base64_decode( $value['encoded_serialized_instance'], true );
                if ( false === $decoded ) {
-                       return null;
+                       return;
                }
 
-               if ( $this->get_instance_hash_key( $decoded ) !== $value['instance_hash_key'] ) {
-                       return null;
+               if ( ! hash_equals( $this->get_instance_hash_key( $decoded ), $value['instance_hash_key'] ) ) {
+                       return;
                }
 
                $instance = unserialize( $decoded );
                if ( false === $instance ) {
-                       return null;
+                       return;
                }
 
                return $instance;
@@ -1207,6 +1212,8 @@ final class WP_Customize_Widgets {
         * @since 3.9.0
         * @access public
         *
+        * @global array $wp_registered_widgets
+        *
         * @param array $widget_ids List of widget IDs.
         * @return array Parsed list of widget IDs.
         */
@@ -1224,6 +1231,9 @@ final class WP_Customize_Widgets {
         * @since 3.9.0
         * @access public
         *
+        * @global array $wp_registered_widget_updates
+        * @global array $wp_registered_widget_controls
+        *
         * @param  string $widget_id Widget ID.
         * @return WP_Error|array Array containing the updated widget information.
         *                        A WP_Error object, otherwise.
@@ -1231,6 +1241,20 @@ final class WP_Customize_Widgets {
        public function call_widget_update( $widget_id ) {
                global $wp_registered_widget_updates, $wp_registered_widget_controls;
 
+               $setting_id = $this->get_setting_id( $widget_id );
+
+               /*
+                * Make sure that other setting changes have previewed since this widget
+                * may depend on them (e.g. Menus being present for Custom Menu widget).
+                */
+               if ( ! did_action( 'customize_preview_init' ) ) {
+                       foreach ( $this->manager->settings() as $setting ) {
+                               if ( $setting->id !== $setting_id ) {
+                                       $setting->preview();
+                               }
+                       }
+               }
+
                $this->start_capturing_option_updates();
                $parsed_id   = $this->parse_widget_id( $widget_id );
                $option_name = 'widget_' . $parsed_id['id_base'];
@@ -1279,8 +1303,8 @@ final class WP_Customize_Widgets {
 
                // Clean up any input vars that were manually added
                foreach ( $added_input_vars as $key ) {
-                       unset( $_POST[$key] );
-                       unset( $_REQUEST[$key] );
+                       unset( $_POST[ $key ] );
+                       unset( $_REQUEST[ $key ] );
                }
 
                // Make sure the expected option was updated.
@@ -1297,25 +1321,30 @@ final class WP_Customize_Widgets {
                        }
                }
 
+               // Obtain the widget instance.
+               $option = $this->get_captured_option( $option_name );
+               if ( null !== $parsed_id['number'] ) {
+                       $instance = $option[ $parsed_id['number'] ];
+               } else {
+                       $instance = $option;
+               }
+
+               /*
+                * Override the incoming $_POST['customized'] for a newly-created widget's
+                * setting with the new $instance so that the preview filter currently
+                * in place from WP_Customize_Setting::preview() will use this value
+                * instead of the default widget instance value (an empty array).
+                */
+               $this->manager->set_post_value( $setting_id, $instance );
+
                // Obtain the widget control with the updated instance in place.
                ob_start();
-
-               $form = $wp_registered_widget_controls[$widget_id];
+               $form = $wp_registered_widget_controls[ $widget_id ];
                if ( $form ) {
                        call_user_func_array( $form['callback'], $form['params'] );
                }
-
                $form = ob_get_clean();
 
-               // Obtain the widget instance.
-               $option = get_option( $option_name );
-
-               if ( null !== $parsed_id['number'] ) {
-                       $instance = $option[$parsed_id['number']];
-               } else {
-                       $instance = $option;
-               }
-
                $this->stop_capturing_option_updates();
 
                return compact( 'instance', 'form' );
@@ -1347,8 +1376,8 @@ final class WP_Customize_Widgets {
                        wp_die( -1 );
                }
 
-               if ( ! isset( $_POST['widget-id'] ) ) {
-                       wp_send_json_error();
+               if ( empty( $_POST['widget-id'] ) ) {
+                       wp_send_json_error( 'missing_widget-id' );
                }
 
                /** This action is documented in wp-admin/includes/ajax-actions.php */
@@ -1362,15 +1391,22 @@ final class WP_Customize_Widgets {
 
                $widget_id = $this->get_post_value( 'widget-id' );
                $parsed_id = $this->parse_widget_id( $widget_id );
-               $id_base   = $parsed_id['id_base'];
-
-               if ( isset( $_POST['widget-' . $id_base] ) && is_array( $_POST['widget-' . $id_base] ) && preg_match( '/__i__|%i%/', key( $_POST['widget-' . $id_base] ) ) ) {
-                       wp_send_json_error();
+               $id_base = $parsed_id['id_base'];
+
+               $is_updating_widget_template = (
+                       isset( $_POST[ 'widget-' . $id_base ] )
+                       &&
+                       is_array( $_POST[ 'widget-' . $id_base ] )
+                       &&
+                       preg_match( '/__i__|%i%/', key( $_POST[ 'widget-' . $id_base ] ) )
+               );
+               if ( $is_updating_widget_template ) {
+                       wp_send_json_error( 'template_widget_not_updatable' );
                }
 
                $updated_widget = $this->call_widget_update( $widget_id ); // => {instance,form}
                if ( is_wp_error( $updated_widget ) ) {
-                       wp_send_json_error();
+                       wp_send_json_error( $updated_widget->get_error_code() );
                }
 
                $form = $updated_widget['form'];
@@ -1408,7 +1444,7 @@ final class WP_Customize_Widgets {
         * @access protected
         *
         * @param string $option_name Option name.
-        * @return boolean Whether the option capture is ignored.
+        * @return bool Whether the option capture is ignored.
         */
        protected function is_option_capture_ignored( $option_name ) {
                return ( 0 === strpos( $option_name, '_transient_' ) );
@@ -1426,6 +1462,25 @@ final class WP_Customize_Widgets {
                return $this->_captured_options;
        }
 
+       /**
+        * Get the option that was captured from being saved.
+        *
+        * @since 4.2.0
+        * @access protected
+        *
+        * @param string $option_name Option name.
+        * @param mixed  $default     Optional. Default value to return if the option does not exist.
+        * @return mixed Value set for the option.
+        */
+       protected function get_captured_option( $option_name, $default = false ) {
+               if ( array_key_exists( $option_name, $this->_captured_options ) ) {
+                       $value = $this->_captured_options[ $option_name ];
+               } else {
+                       $value = $default;
+               }
+               return $value;
+       }
+
        /**
         * Get the number of captured widget option updates.
         *
@@ -1460,21 +1515,21 @@ final class WP_Customize_Widgets {
         * @since 3.9.0
         * @access public
         *
-        * @param mixed $new_value
-        * @param string $option_name
-        * @param mixed $old_value
-        * @return mixed
+        * @param mixed  $new_value   The new option value.
+        * @param string $option_name Name of the option.
+        * @param mixed  $old_value   The old option value.
+        * @return mixed Filtered option value.
         */
        public function capture_filter_pre_update_option( $new_value, $option_name, $old_value ) {
                if ( $this->is_option_capture_ignored( $option_name ) ) {
                        return;
                }
 
-               if ( ! isset( $this->_captured_options[$option_name] ) ) {
+               if ( ! isset( $this->_captured_options[ $option_name ] ) ) {
                        add_filter( "pre_option_{$option_name}", array( $this, 'capture_filter_pre_get_option' ) );
                }
 
-               $this->_captured_options[$option_name] = $new_value;
+               $this->_captured_options[ $option_name ] = $new_value;
 
                return $old_value;
        }
@@ -1485,14 +1540,14 @@ final class WP_Customize_Widgets {
         * @since 3.9.0
         * @access public
         *
-        * @param mixed $value Option
-        * @return mixed
+        * @param mixed $value Value to return instead of the option value.
+        * @return mixed Filtered option value.
         */
        public function capture_filter_pre_get_option( $value ) {
                $option_name = preg_replace( '/^pre_option_/', '', current_filter() );
 
-               if ( isset( $this->_captured_options[$option_name] ) ) {
-                       $value = $this->_captured_options[$option_name];
+               if ( isset( $this->_captured_options[ $option_name ] ) ) {
+                       $value = $this->_captured_options[ $option_name ];
 
                        /** This filter is documented in wp-includes/option.php */
                        $value = apply_filters( 'option_' . $option_name, $value );
@@ -1521,4 +1576,36 @@ final class WP_Customize_Widgets {
                $this->_captured_options = array();
                $this->_is_capturing_option_updates = false;
        }
+
+       /**
+        * @since 3.9.0
+        * @deprecated 4.2.0 Deprecated in favor of customize_dynamic_setting_args filter.
+        */
+       public function setup_widget_addition_previews() {
+               _deprecated_function( __METHOD__, '4.2.0' );
+       }
+
+       /**
+        * @since 3.9.0
+        * @deprecated 4.2.0 Deprecated in favor of customize_dynamic_setting_args filter.
+        */
+       public function prepreview_added_sidebars_widgets() {
+               _deprecated_function( __METHOD__, '4.2.0' );
+       }
+
+       /**
+        * @since 3.9.0
+        * @deprecated 4.2.0 Deprecated in favor of customize_dynamic_setting_args filter.
+        */
+       public function prepreview_added_widget_instance() {
+               _deprecated_function( __METHOD__, '4.2.0' );
+       }
+
+       /**
+        * @since 3.9.0
+        * @deprecated 4.2.0 Deprecated in favor of customize_dynamic_setting_args filter.
+        */
+       public function remove_prepreview_filters() {
+               _deprecated_function( __METHOD__, '4.2.0' );
+       }
 }