<?php
/**
* Theme previews using the Site Editor for block themes.
*
* @package WordPress
*/
/**
* Filters the blog option to return the path for the previewed theme.
*
* @since 6.3.0
*
* @param string $current_stylesheet The current theme's stylesheet or template path.
* @return string The previewed theme's stylesheet or template path.
*/
function wp_get_theme_preview_path( $current_stylesheet = null ) {
if ( ! current_user_can( 'switch_themes' ) ) {
return $current_stylesheet;
}
$preview_stylesheet = ! empty( $_GET['wp_theme_preview'] ) ? sanitize_text_field( wp_unslash( $_GET['wp_theme_preview'] ) ) : null;
$wp_theme = wp_get_theme( $preview_stylesheet );
if ( ! is_wp_error( $wp_theme->errors() ) ) {
if ( current_filter() === 'template' ) {
$theme_path = $wp_theme->get_template();
} else {
$theme_path = $wp_theme->get_stylesheet();
}
return sanitize_text_field( $theme_path );
}
return $current_stylesheet;
}
/**
* Adds a middleware to `apiFetch` to set the theme for the preview.
* This adds a `wp_theme_preview` URL parameter to API requests from the Site Editor, so they also respond as if the theme is set to the value of the parameter.
*
* @since 6.3.0
*/
function wp_attach_theme_preview_middleware() {
// Don't allow non-admins to preview themes.
if ( ! current_user_can( 'switch_themes' ) ) {
return;
}
wp_add_inline_script(
'wp-api-fetch',
sprintf(
'wp.apiFetch.use( wp.apiFetch.createThemePreviewMiddleware( %s ) );',
wp_json_encode( sanitize_text_field( wp_unslash( $_GET['wp_theme_preview'] ) ) )
),
'after'
);
}
/**
* Set a JavaScript constant for theme activation.
*
* Sets the JavaScript global WP_BLOCK_THEME_ACTIVATE_NONCE containing the nonce
* required to activate a theme. For use within the site editor.
*
* @see https://github.com/WordPress/gutenberg/pull/41836
*
* @since 6.3.0
* @access private
*/
function wp_block_theme_activate_nonce() {
$nonce_handle = 'switch-theme_' . wp_get_theme_preview_path();
?>
<script type="text/javascript">
window.WP_BLOCK_THEME_ACTIVATE_NONCE = <?php echo wp_json_encode( wp_create_nonce( $nonce_handle ) ); ?>;
</script>
<?php
}
/**
* Add filters and actions to enable Block Theme Previews in the Site Editor.
*
* The filters and actions should be added after `pluggable.php` is included as they may
* trigger code that uses `current_user_can()` which requires functionality from `pluggable.php`.
*
* @since 6.3.2
*/
function wp_initialize_theme_preview_hooks() {
if ( ! empty( $_GET['wp_theme_preview'] ) ) {
add_filter( 'stylesheet', 'wp_get_theme_preview_path' );
add_filter( 'template', 'wp_get_theme_preview_path' );
add_action( 'init', 'wp_attach_theme_preview_middleware' );
add_action( 'admin_head', 'wp_block_theme_activate_nonce' );
}
}