Optimizely comes with default editing previews for image and video typed content data. However, you may need to customize the editing preview for images or video, or perhaps add an editing preview for a media type. You can add or change a preview in the templating system in Optimizely.
## Customize a preview template
Sites often have a specific design for media content, such as displaying a caption with each image, or displaying a document as a link with size and format information. To add a useful preview for editors in edit mode. add a new template with a `
TemplateDescriptor` attribute that is tagged as preview. Then extend the `
IRenderTemplate<T>` class where T is the content type to preview as shown in the following example that register a MVC controller as a preview template for Document.
## Enable on-page edit
For media that is not an image or a video, the on-page edit mode is disabled by default because there is nothing to display in the editing preview. However, if you add an editing preview for a new type, then it follows that you may want to have on-page edit mode enabled for that type. Add a `
UIDescriptor` for your media content type to override the default settings for media content. Then, you can specify which edit view is the default and, if required, disable particular edit views.
The following example creates a `
UIDescriptor` for a document content type and set the default edit view to all properties mode.