Extensibility

Extending the Library from Other Mods

The library provides a Widget Transformer Pipeline that allows third-party mods to modify widgets inside existing GUI screens without Harmony patches or copying source code.

How it works

Before any widget is inflated into an element, the library checks whether any transformers are registered for that widget's Key. If yes, the widget passes through the transformer chain and the result is used instead of the original.

Only widgets with an explicit Key are eligible. Keyless widgets are never intercepted.

Registering a transformer

Call WidgetTransformerRegistry.Register in your ModSystem.Start():

public class MyMod : ModSystem
{
  public override void Start(ICoreAPI api)
  {
    WidgetTransformerRegistry.Register(
      new ValueKey<string>("hud.status_bars"),
      new MyStatusBarTransformer()
    );
  }
}

Implement IWidgetTransformer to define what changes to make:

class MyStatusBarTransformer : IWidgetTransformer
{
  public Widget Transform(Widget widget)
  {
    var row = (Row)widget;
    return new Row(
      key: row.Key,
      children: [..row.Children, new MyStatusBar()]
    );
  }
}

The transformer receives the widget produced by the library (or by the previous transformer), and must return a valid replacement of the same type and key.

Priority

Multiple mods can transform the same widget. Use priority to control order — lower value runs first (default: 0):

WidgetTransformerRegistry.Register(key, transformer, priority: 10);

Each transformer receives the output of the previous one, so they compose cleanly.