screens

Screens in FlatRedBall2

A Screen is the top-level container for a game state — a level, a menu, a game-over sequence. Each screen owns its entities, collision relationships, Gum UI, and camera. Only one screen is active at a time.

Creating a Screen

Subclass Screen and override the lifecycle hooks you need:

public class GameScreen : Screen
{
    private Factory<Player> _playerFactory = null!;

    public override void CustomInitialize()
    {
        // Create factories, entities, collision relationships, Gum UI
        _playerFactory = new Factory<Player>(this);
        _playerFactory.Create();
    }

    public override void CustomActivity(FrameTime time)
    {
        // Per-frame game logic (after physics and collision have already run)
    }

    public override void CustomDestroy()
    {
        // Optional cleanup before the screen is torn down
        // Factories and entities are destroyed automatically — only needed
        // for external resources you opened manually
    }
}

Lifecycle Order Each Frame

See engine-overview for the full 8-step frame loop. Key ordering for screens:

• Entity CustomActivity runs before Screen CustomActivity — the screen always sees post-entity, post-collision state.
• CustomInitialize runs once when the screen is activated, before the first frame.

What's Available on a Screen

Property	Type	Notes
Camera	Camera	This screen's camera — set background color, world bounds, position
Engine	FlatRedBallService	Access to Random, Input, Audio, etc.
ContentLoader	ContentLoader	Load textures, fonts, and other content
RenderList	IReadOnlyList<IRenderable>	All renderables sorted and drawn each frame; use Add/Remove to modify
Layers	List<Layer>	Named layers for render ordering

Returning Data from a Sub-Screen

When a sub-screen (e.g., a battle screen) needs to pass results back to the parent, use the configure callback on the return transition. The configure runs before the destination screen's CustomInitialize, so the data is ready immediately: