Trait Renderer 

pub trait Renderer {
    type Scene: RenderScene;
    type Error;

    // Required methods
    fn scene(&self) -> &Self::Scene;
    fn scene_mut(&mut self) -> &mut Self::Scene;
    fn rebuild_scene(
        &mut self,
        layout_tree: &LayoutTree,
        viewport: Size,
    ) -> Result<(), Self::Error>;
    fn rebuild_scene_from_applier(
        &mut self,
        applier: &mut MemoryApplier,
        root: NodeId,
        viewport: Size,
    ) -> Result<(), Self::Error>;

    // Provided methods
    fn attach_app_context_services(&mut self, _app_context: &AppContext) { ... }
    fn update_scene_from_applier(
        &mut self,
        applier: &mut MemoryApplier,
        root: NodeId,
        viewport: Size,
        dirty_nodes: &[NodeId],
    ) -> Result<(), Self::Error> { ... }
    fn update_visual_scene_from_applier(
        &mut self,
        applier: &mut MemoryApplier,
        root: NodeId,
        viewport: Size,
        dirty_nodes: &[NodeId],
    ) -> Result<(), Self::Error> { ... }
    fn draw_dev_overlay(&mut self, _text: &str, _viewport: Size) { ... }
    fn needs_frame_warmup(&self) -> bool { ... }
}

Abstraction implemented by concrete renderer backends.

Required Associated Types

type Scene: RenderScene

type Error

Required Methods

fn scene(&self) -> &Self::Scene

fn scene_mut(&mut self) -> &mut Self::Scene

fn rebuild_scene( &mut self, layout_tree: &LayoutTree, viewport: Size, ) -> Result<(), Self::Error>

fn rebuild_scene_from_applier( &mut self, applier: &mut MemoryApplier, root: NodeId, viewport: Size, ) -> Result<(), Self::Error>

Rebuilds the scene by traversing the LayoutNode tree directly via Applier.

This is the new architecture that eliminates per-frame LayoutTree reconstruction. Implementors must read layout state from LayoutNode.layout_state() directly.

Provided Methods

fn attach_app_context_services(&mut self, _app_context: &AppContext)

Installs renderer-provided app services into the target AppContext.

AppShell calls this before the first composition pass. Renderers that provide text measurement or other per-app services should install them here rather than as constructor side effects.

fn update_scene_from_applier( &mut self, applier: &mut MemoryApplier, root: NodeId, viewport: Size, dirty_nodes: &[NodeId], ) -> Result<(), Self::Error>

fn update_visual_scene_from_applier( &mut self, applier: &mut MemoryApplier, root: NodeId, viewport: Size, dirty_nodes: &[NodeId], ) -> Result<(), Self::Error>

fn draw_dev_overlay(&mut self, _text: &str, _viewport: Size)

Draw a development overlay (e.g., FPS counter) on top of the scene.

This is called after rebuild_scene when dev options are enabled. The text is drawn directly by the renderer without affecting composition.

Default implementation does nothing.

fn needs_frame_warmup(&self) -> bool

Returns whether renderer-side cache materialization needs a visible follow-up frame.

Dyn Compatibility

This trait is dyn compatible.

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

Implementors