ThemeNegotiatorInterface
interface ThemeNegotiatorInterface (View source)
Defines an interface for classes which determine the active theme.
To set the active theme, create a new service tagged with 'theme_negotiator' (see the theme.negotiator.admin_theme service in user.services.yml for an example). Your service class needs to implement this interface.
If you are setting a theme which is closely tied to the functionality of a particular page or set of pages (such that the page might not function correctly if a different theme is used), make sure to set the priority on the service to a high number so that it is not accidentally overridden by other theme negotiators. By convention, a priority of "1000" is used in these cases; see \Drupal\Core\Theme\AjaxBasePageNegotiator and core.services.yml for an example.
Methods
Whether this theme negotiator should be used to set the theme.
Details
bool
applies(RouteMatchInterface $route_match)
Whether this theme negotiator should be used to set the theme.
string|null
determineActiveTheme(RouteMatchInterface $route_match)
Determine the active theme for the request.