A ViewController descendant that applies conditional appearance rules to specified UI elements.
NuGet Package: DevExpress.ExpressApp.ConditionalAppearance
The Appearance Controller provides members that apply conditional appearance rules to the specified UI elements. So, the AppearanceController.RefreshItemAppearance method can be invoked from any View Controller to apply appropriate conditional appearance rules to the passed UI element (View Item, Layout Item or an Action). For instance, the ListViewItemAppearanceController invokes this method to apply the appropriate conditional appearance rules to the properties displayed in the current List View. However, there are common scenarios when a conditional appearance must be refreshed for UI elements of different types at the same time. For instance, when a View’s current object is changed, the conditional appearance must be refreshed for Detail View Items, Layout Items and Actions. So, we introduced the ISupportRefreshItemsAppearance interface. The Controllers that support this interface implement the RefreshViewItemsAppearance method. In this method, they call the Appearance Controller’s RefreshItemAppearance method for each target UI element. To invoke the ISupportRefreshItemsAppearance.RefreshViewItemsAppearance method in common scenarios, these Controllers are registered in the Appearance Controller. This Controller’s AppearanceController.Refresh method calls the ISupportRefreshItemsAppearance.RefreshViewItemsAppearance method for all registered Controllers to refresh the conditional appearance for UI elements of difference types in a particular scenario.
To learn about the conditional appearance rule, refer to the Conditional Appearance Module Overview topic. To learn how to declare rules, refer to the Declare Conditional Appearance Rules in the Application Model and Declare Conditional Appearance Rules in Code topics.
You can influence the way the Appearance Controller collects and applies conditional appearance rules. For this purpose, handle the following events:
Refer to the How to: Customize the Conditional Appearance Module Behavior topic to see the examples of handling these events.