Trait CustomElement 

pub trait CustomElement:
    Debug
    + Send
    + Sync {
    // Required methods
    fn element_type(&self) -> &'static str;
    fn render(
        &self,
        element: &LayoutElement,
        ctx: &DataContext,
        render_ctx: &RenderContext<'_>,
        painter: &mut dyn Painter,
    ) -> Result<(), RenderError>;

    // Provided method
    fn schema(&self) -> ComponentSchema { ... }
}

A custom layout element that can be registered from any game or plugin.

Implement this trait to provide rendering logic for a new element type (e.g. custom:monster_sprite, custom:hp_bar). Once registered via ElementRegistry::register, the layout engine will dispatch elements of that type to the implementation’s render method.

Required Methods

fn element_type(&self) -> &'static str

Returns the unique element type identifier.

This string is matched against the type field in a LayoutElement at dispatch time. Convention: use a colon-prefixed namespace, e.g. "custom:monster_sprite" or "custom:hp_bar".

fn render( &self, element: &LayoutElement, ctx: &DataContext, render_ctx: &RenderContext<'_>, painter: &mut dyn Painter, ) -> Result<(), RenderError>

Render this custom element into the framebuffer.

Arguments

• element — The layout element definition (contains id, rect, element-specific params, etc.).
• ctx — Per-frame mutable data context for template variables.
• render_ctx — Shared immutable rendering state (screen, theme, fonts, tilesets).
• painter — The painter used to draw into the framebuffer.

Provided Methods

fn schema(&self) -> ComponentSchema

The prop schema this element expects.

Used by ElementRegistry::validate_layout to check layouts at load time. The default (empty) schema accepts any props — override it to get required-prop and type checking. Keep it in sync with the component declaration in the game’s .gui prelude; a unit test deserialising a schema-shaped params object through the element’s own param struct is the cheapest drift guard.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors