protected function extract_images_from_galleries( $richtext, $plaintext, $extra_args = array() ) {
		if ( ! isset( $extra_args['post'] ) || ! is_a( $extra_args['post'], 'WP_Post' ) ) {
			$post = new WP_Post( (object) array( 'post_content' => $richtext ) );
		} else {
			$post = $extra_args['post'];
		}

		// We're not using get_post_galleries_images() because it returns thumbnails; we want the original image.
		$galleries      = get_post_galleries( $post, false );
		$galleries_data = array();

		if ( ! empty( $galleries ) ) {
			// Validate the size of the images requested.
			if ( isset( $extra_args['width'] ) ) {

				// A width was specified but not a height, so calculate it assuming a 4:3 ratio.
				if ( ! isset( $extra_args['height'] ) && ctype_digit( $extra_args['width'] ) ) {
					$extra_args['height'] = round( ( $extra_args['width'] / 4 ) * 3 );
				}

				if ( ctype_digit( $extra_args['width'] ) ) {
					$image_size = array( $extra_args['width'], $extra_args['height'] );
				} else {
					$image_size = $extra_args['width'];  // E.g. "thumb", "medium".
				}

			} else {
				$image_size = 'full';
			}

			/**
			 * There are two variants of gallery shortcode.
			 *
			 * One kind specifies the image (post) IDs via an `ids` parameter.
			 * The other gets the image IDs from post_type=attachment and post_parent=get_the_ID().
			 */

			foreach ( $galleries as $gallery_id => $gallery ) {
				$data   = array();
				$images = array();

				// Gallery ids= variant.
				if ( isset( $gallery['ids'] ) ) {
					$images = wp_parse_id_list( $gallery['ids'] );

				// Gallery post_parent variant.
				} elseif ( isset( $extra_args['post'] ) ) {
					$images = wp_parse_id_list(
						get_children( array(
							'fields'         => 'ids',
							'order'          => 'ASC',
							'orderby'        => 'menu_order ID',
							'post_mime_type' => 'image',
							'post_parent'    => $extra_args['post']->ID,
							'post_status'    => 'inherit',
							'post_type'      => 'attachment',
						) )
					);
				}

				// Extract the data we need from each image in this gallery.
				foreach ( $images as $image_id ) {
					$image  = wp_get_attachment_image_src( $image_id, $image_size );
					$data[] = array(
						'url'    => $image[0],
						'width'  => $image[1],
						'height' => $image[2],

						'gallery_id' => 1 + $gallery_id,
					);
				}

				$galleries_data[] = $data;
			}
		}

		/**
		 * Filters image galleries extracted from text.
		 *
		 * @since 2.3.0
		 *
		 * @param array  $galleries_data Galleries. See {@link BP_Media_Extractor::extract_images_from_galleries()}.
		 * @param string $richtext       Content to parse.
		 * @param string $plaintext      Copy of $richtext without any markup.
		 * @param array  $extra_args     Bespoke data for a particular extractor.
		 */
		return apply_filters( 'bp_media_extractor_galleries', $galleries_data, $richtext, $plaintext, $extra_args );
	}