Editor Documentation

you can do custom documentation on classes and properties by using .udn files. This is what is used when in the tooltip you see “Hold (Ctrl + Alt) for more”.

Resources

• See FDocumentationModule

When is it displayed ?

As far I saw:

• For Types
  • Displays when you hover a class in the class picker when you create a Blueprint
  • Displays when you hover a class in the component class picker inside an actor.
• For nodes
  • Displays when you hover a node in graph editor.

How to use

(Thanks to Hojo)

Not working?

• Be sure to have a “default” tooltip set on your class/struct/property! In some cases the documentation tooltip widget will not be used if there isn’t a default tooltip text set (see FDocumentation::CreateToolTip for the default behavior).
• Only works on “item” properties (if you are doing a property tooltip). So you cannot have a udn tooltip on Arrays, Maps or Sets properties.

1. Get a template from UE_5.X\Engine\Documentation\Source\Shared. For example UE_5.X\Engine\Documentation\Source\Shared\Types\UActorComponent\UActorComponent.INT.udn
2. Use a toll such a VSCode to have a live markdown preview.
3. Put the file in your project/plugin Documentation/Source/XXX folder, if its a type the path is Documentation/Source/Shared/Types/UMyTypeName/UMyTypeName.INT.udn
4. Set the content inside (use the various engine .udn files for examples)

This also works for structs and individual class/struct properties. See Documentation\Source\Shared\Types\FBodyInstance for an example.

To add images
Use ![](MyImage.png), the file must be in a Images folder next to your .udn file.

How it works

The FDocumentationModule has a private var of type IDocumentation which seems to keep track of the SourcePaths as well as the LoadedPages.

See also GetDocumentationLink and GetEnumDocumentationLink in PropertyEditorHelpers. See also FUDNParser. For property tooltips see FPropertyEditor::GetDocumentationLink and FPropertyEditor::GetDocumentationExcerptName and SDocumentationToolTip.

Miscs

For images FSlateRenderer::GenerateDynamicImageResource is what is used to get the desired size (which should point to FSlateRHIRenderer::GenerateDynamicImageResource).