UI Module

The UI module is still incipient, but its direction is clear: Byte Engine is building a retained, async-friendly UI layer that can live inside the engine render loop.

The current surface is centered on async component functions that receive a layout Context. Those functions create elements through stable named slots, wait for events, and can mount child components that return values to their caller. The runtime keeps retained state between evaluations so application code does not have to rebuild every interaction from scratch.

Main pieces

• layout::engine::Engine evaluates retained UI and produces render data.
• Context and ContainerContext are the component-facing construction and event APIs.
• Container, Text, TextField, Image, Curve, and Shape are the current built-in primitives.
• UiRenderPass turns evaluated UI render data into GPU draw work.
• ConcreteStyle, ConcreteLayer, Transform, and Visual hold styling, animation-oriented transforms, and opacity.

The layout layer is intentionally small. Containers own sizing, positioning, flow, clipping, style, and visual data. Flow functions such as row, column, grid, and centered variants place children. Transforms are best treated as animation and presentation state, while position and sizing describe stable layout.

Events and focus

UI events are exposed as futures. A component can wait for pointer-style events, keys, text edits, timers, or render ticks. Text input is app-owned: TextField emits edit deltas such as inserted and deleted characters, and application state decides how to apply them.

Focus is explicit. Components can request or release focus, and focused elements are the ones that should receive key and text-edit events.

Current limitations

The module is not a full widget toolkit yet. It is better understood as a retained primitive layer plus async interaction model. Higher-level widgets should stay small and should prefer normal composition over new runtime machinery.

When adding UI features, keep the existing route in mind:

• build or update a primitive
• let layout evaluate geometry, clipping, and retained identity
• let UiRenderPass consume the render data

That path keeps UI code testable and avoids coupling application widgets directly to renderer resource ownership.