The DevExpress ASP.NET MVC HTML Editor provides you with an ability to process an uploaded file before it is saved to the server. You can process image, audio, video, and flash files in controller actions specified using the following properties: SettingsImageUpload.UploadCallbackRouteValues, SettingsAudioUpload.UploadCallbackRouteValues, SettingsVideoUpload.UploadCallbackRouteValues, and SettingsFlashUpload.UploadCallbackRouteValues.
In this demo, image file saving callback is handled by a controller action specified using the SettingsImageUpload.UploadCallbackRouteValues property. In this action, an uploaded image is overplayed with the watermark text and resized to fit the specified size limitation.