wp_get_global_styles_svg_filters

wp_get_global_styles_svg_filters: 这个函数返回svg-filters.css文件的内容，该文件用于WordPress管理界面中SVG过滤器的样式。

返回一个包含SVG的字符串，作为过滤器被引用（双色调）。

function wp_get_global_styles_svg_filters() {
	// Return cached value if it can be used and exists.
	// It's cached by theme to make sure that theme switching clears the cache.
	$can_use_cached = (
		( ! defined( 'WP_DEBUG' ) || ! WP_DEBUG ) &&
		( ! defined( 'SCRIPT_DEBUG' ) || ! SCRIPT_DEBUG ) &&
		( ! defined( 'REST_REQUEST' ) || ! REST_REQUEST ) &&
		! is_admin()
	);
	$transient_name = 'global_styles_svg_filters_' . get_stylesheet();
	if ( $can_use_cached ) {
		$cached = get_transient( $transient_name );
		if ( $cached ) {
			return $cached;
		}
	}

	$supports_theme_json = WP_Theme_JSON_Resolver::theme_has_support();

	$origins = array( 'default', 'theme', 'custom' );
	if ( ! $supports_theme_json ) {
		$origins = array( 'default' );
	}

	$tree = WP_Theme_JSON_Resolver::get_merged_data();
	$svgs = $tree->get_svg_filters( $origins );

	if ( $can_use_cached ) {
		// Cache for a minute, same as wp_get_global_stylesheet.
		set_transient( $transient_name, $svgs, MINUTE_IN_SECONDS );
	}

	return $svgs;
}