Overlayi

Overlayi is a cross-platform software library that provides a declarative framework for creating and rendering overlay elements that appear above primary content. It is designed for web, desktop, and mobile applications, and is commonly used to implement tooltips, modals, banners, heads-up displays, and video overlays without requiring low-level manual layering.

The library organizes overlays into a layered composition model. Overlayi describes each overlay in terms of its content, position, z-order, visibility, and transitions. It includes a lightweight scene graph of overlay nodes, supports animated show and hide, adaptive layouts, focus management, and accessibility hooks. Overlays can be anchored to elements or coordinates, can respond to events from the underlying content, and can be dynamically added or removed during runtime.

Implementation and usage: Overlayi provides a runtime that integrates with existing rendering pipelines and supports theming and custom renderers. It uses a reactive update model so state changes propagate efficiently, and it offers stacking contexts to prevent visual conflicts with the base UI. Bindings exist for common web and mobile frameworks through adapters, making it possible to reuse overlays across platforms.

History and reception: Overlayi originated in UI tooling communities to address the challenges of managing multiple overlay layers. It has been adopted in several projects for prototyping and production interfaces, and is noted for simplifying overlay coordination and improving performance by isolating overlay rendering from core content.

See also: overlay, z-index, compositing, heads-up display, tooltips.