_mce_set_direction() │ WP 2.1.0

Sets the localized direction for MCE plugin.

Will only set the direction to 'rtl', if the WordPress locale has the text direction set to 'rtl'.

Fills in the 'directionality' setting, enables the 'directionality' plugin, and adds the 'ltr' button to 'toolbar1', formerly 'theme_advanced_buttons1' array keys. These keys are then returned in the $mce_init (TinyMCE settings) array.

Internal function — this function is designed to be used by the kernel itself. It is not recommended to use this function in your code.

No Hooks.

Returns

Array. Direction set for 'rtl', if needed by locale.

Usage

_mce_set_direction( $mce_init );
$mce_init(array) (required)
MCE settings array.

Changelog

Since 2.1.0 Introduced.

_mce_set_direction() code WP 6.8.1

wp-includes/functions.php 
function _mce_set_direction( $mce_init ) {
	if ( is_rtl() ) {
		$mce_init['directionality'] = 'rtl';
		$mce_init['rtl_ui']         = true;

		if ( ! empty( $mce_init['plugins'] ) && ! str_contains( $mce_init['plugins'], 'directionality' ) ) {
			$mce_init['plugins'] .= ',directionality';
		}

		if ( ! empty( $mce_init['toolbar1'] ) && ! preg_match( '/\bltr\b/', $mce_init['toolbar1'] ) ) {
			$mce_init['toolbar1'] .= ',ltr';
		}
	}

	return $mce_init;
}