WP_Customize_Setting::preview() – Add filters to supply the setting’s value when accessed.

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Description

Add filters to supply the setting's value when accessed.

If the setting already has a pre-existing value and there is no incoming post value for the setting, then this method will short-circuit since there is no change to preview.

Usage

$bool = WP_Customize_Setting::preview();

Parameters

Returns

bool False when preview short-circuits due no change needing to be previewed.

Source

File name: wordpress/wp-includes/class-wp-customize-setting.php
Lines:

1 to 100 of 100
  public function preview() {
    if ( ! isset( $this->_previewed_blog_id ) ) {
      $this->_previewed_blog_id = get_current_blog_id();
    }

    // Prevent re-previewing an already-previewed setting.
    if ( $this->is_previewed ) {
      return true;
    }

    $id_base                 = $this->WP_Customize_Setting::id_data['base'];
    $is_multidimensional     = ! empty( $this->WP_Customize_Setting::id_data['keys'] );
    $multidimensional_filter = array( $this, '_multidimensional_preview_filter' );

    /*
		 * Check if the setting has a pre-existing value (an isset check),
		 * and if doesn't have any incoming post value. If both checks are true,
		 * then the preview short-circuits because there is nothing that needs
		 * to be previewed.
		 */
    $undefined     = new stdClass();
    $needs_preview = ( $undefined !== $this->WP_Customize_Setting::post_value( $undefined ) );
    $value         = null;

    // Since no post value was defined, check if we have an initial value set.
    if ( ! $needs_preview ) {
      if ( $this->is_multidimensional_aggregated ) {
        $root  = self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['root_value'];
        $value = $this->WP_Customize_Setting::multidimensional_get( $root, $this->WP_Customize_Setting::id_data['keys'], $undefined );
      } else {
        $default       = $this->default;
        $this->default = $undefined; // Temporarily set default to undefined so we can detect if existing value is set.
        $value         = $this->WP_Customize_Setting::value();
        $this->default = $default;
      }
      $needs_preview = ( $undefined === $value ); // Because the default needs to be supplied.
    }

    // If the setting does not need previewing now, defer to when it has a value to preview.
    if ( ! $needs_preview ) {
      if ( ! has_action( "customize_post_value_set_{$this->id}", array( $this, 'preview' ) ) ) {
        add_action( "customize_post_value_set_{$this->id}", array( $this, 'preview' )  < );
      }
      return false;
    }

    switch ( $this->type ) {
      case 'theme_mod':
        if ( ! $is_multidimensional ) {
          add_filter( "theme_mod_{$id_base}", array( $this, '_preview_filter' )  < );
        } else {
          if ( empty( self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['previewed_instances'] ) ) {
            // Only add this filter once for this ID base.
            add_filter( "theme_mod_{$id_base}", $multidimensional_filter )  <;
          }
          self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['previewed_instances'][ $this->id ] = $this;
        }
        break;
      case 'option':
        if ( ! $is_multidimensional ) {
          add_filter( "pre_option_{$id_base}", array( $this, '_preview_filter' )  < );
        } else {
          if ( empty( self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['previewed_instances'] ) ) {
            // Only add these filters once for this ID base.
            add_filter( "option_{$id_base}", $multidimensional_filter )  <;
            add_filter( "default_option_{$id_base}", $multidimensional_filter )  <;
          }
          self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['previewed_instances'][ $this->id ] = $this;
        }
        break;
      default:
        
/**
 * Fires when the WP_Customize_Setting::preview() method is called for settings
 * not handled as theme_mods or options.
 *
 * The dynamic portion of the hook name, `$this->id`, refers to the setting ID.
 *
 * @since 3.4.0
 *
 * @param WP_Customize_Setting $setting WP_Customize_Setting instance.
 */
        do_action( "customize_preview_{$this->id}", $this );

        
/**
 * Fires when the WP_Customize_Setting::preview() method is called for settings
 * not handled as theme_mods or options.
 *
 * The dynamic portion of the hook name, `$this->type`, refers to the setting type.
 *
 * @since 4.1.0
 *
 * @param WP_Customize_Setting $setting WP_Customize_Setting instance.
 */
        do_action( "customize_preview_{$this->type}", $this );
    }

    $this->is_previewed = true;

    return true;
  }
 

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