How to: Customize Built-in Command Using Service Substitution

  • 3 minutes to read

To change the actions performed when the built-in command is executed, use the service substitution technique. Create the IRichEditCommandFactoryService descendant which generates custom commands and use the RichEditControl.ReplaceService<T> method (or the GetService -> RemoveService -> AddService method sequence) to replace default service with a newly created service.

The following code replaces the IRichEditCommandFactoryService service with its customized descendant.

richEditControl.Text = "A message box is displayed after saving a document using the 'Save' or 'Save As' button click since custom commands.";
var myCommandFactory = new CustomRichEditCommandFactoryService(richEditControl, richEditControl.GetService<IRichEditCommandFactoryService>());
richEditControl.ReplaceService<IRichEditCommandFactoryService>(myCommandFactory);

The following code implements the IRichEditCommandFactoryService descendant which generates customized SaveDocumentCommand and SaveDocumentAsCommand commands. The command descendants override the ExecuteCore methods to display a message after a document has been saved. The IsModified internal property indicates unsaved changes in the document. If this property is not changed to false after saving a document, it signals that the save action failed.

public class CustomRichEditCommandFactoryService : IRichEditCommandFactoryService {
    readonly IRichEditCommandFactoryService service;
    readonly RichEditControl control;

    public CustomRichEditCommandFactoryService(RichEditControl control, IRichEditCommandFactoryService service) {
        DevExpress.Utils.Guard.ArgumentNotNull(control, "control");
        DevExpress.Utils.Guard.ArgumentNotNull(service, "service");
        this.control = control;
        this.service = service;
    }

    public RichEditCommand CreateCommand(RichEditCommandId id) {
        if(id == RichEditCommandId.FileSaveAs) {
            return new CustomSaveDocumentAsCommand(control);
        }
        if(id == RichEditCommandId.FileSave) {
            return new CustomSaveDocumentCommand(control);
        }
        return service.CreateCommand(id);
    }
}

public class CustomSaveDocumentCommand : SaveDocumentCommand {
    public CustomSaveDocumentCommand(IRichEditControl richEdit) : base(richEdit) { }

    protected override void ExecuteCore() {
        base.ExecuteCore();
        if(!DocumentServer.Modified) {
            MessageBox.Show("Document is saved successfully");
        }
    }
}


public class CustomSaveDocumentAsCommand : SaveDocumentAsCommand {
    public CustomSaveDocumentAsCommand(IRichEditControl richEdit) : base(richEdit) { }

    protected override void ExecuteCore() {
        DocumentServer.Modified = true;
        base.ExecuteCore();
        if(!DocumentServer.Modified) {
            MessageBox.Show("Document is saved successfully");    
        }                
    }
}