Crate cotis_layout 

Reference layout engine for Cotis element trees.

cotis-layout implements Cotis’s LayoutManager and LayoutFrameManager traits. It runs a flexbox-like sizing and positioning pass over a configured element tree and produces a stream of RenderCommandOutput values for downstream pipes (typically cotis-pipes) and renderers.

Frame lifecycle

1. Create a CotisLayoutManager with the viewport Dimensions.
2. Wire it into a CotisApp with a renderer. The renderer supplies a text measurer and window dimensions via LayoutManagerCompatible.
3. Each frame: begin_frame() returns a CotisLayoutRun.
4. UI code opens elements through ConfigureElements (open_new_element, set_config, close_element).
5. Text leaves use ConfigureLeafElements with TextElementConfig.
6. end() runs layout (fit/grow/shrink, text wrap, positioning) and yields an iterator of RenderCommandOutput.
7. A pipe such as CotisLayoutToRenderListPipeForGenerics converts those commands into renderer-specific draw lists.

Quick start

For a runnable desktop demo, use a renderer backend such as cotis-wgpu or cotis-raylib. Local examples under examples/ mirror the same wiring once ecosystem crates are on crates.io. A minimal setup looks like:

use cotis::cotis_app::CotisApp;
use cotis_layout::preamble::CotisLayoutManager;
use cotis_pipes::cotis_layout_pipes::CotisLayoutToRenderListPipeForGenerics;
use cotis_utils::math::Dimensions;

let dimensions = Dimensions::new(800.0, 600.0);
let manager = CotisLayoutManager::new(dimensions);
// let app = CotisApp::new(renderer, manager, CotisLayoutToRenderListPipeForGenerics);

Modules

• preamble — convenience re-exports: CotisLayoutManager, CotisLayoutRun, TextConfigurable.
• layout_traits — CotisLayoutCompatible, the bridge trait for custom config types.
• layout_struct — layout output types (RenderCommandOutput, clip markers, TextDrawPayload).
• cotis_traits — Cotis trait implementations for the default ElementConfig integration path and element-state query hooks.

Generic config types

To use a config type other than ElementConfig, implement CotisLayoutCompatible to map your type into the internal layout style representation, and TextConfigurable if your type supports text leaves. Built-in wiring for ElementConfig lives in cotis_traits.

Inspecting layout state

After a frame completes, CotisLayoutManager::get_cache_element exposes a snapshot of the last layout tree for debugging and hit-testing. cotis_traits::secondary_traits implements cotis_utils::element_state query traits on that cache.

Cargo features

Feature	Effect
serialization	Enables serde on render output types and serialization in cotis, cotis-defaults, and cotis-utils.

Modules

cotis_traits

Cotis trait implementations wiring CotisLayoutManager into the standard frame and element configuration API.

layout_struct

Layout output types consumed by pipes and renderers.

layout_traits

Bridge trait connecting custom element config types to the layout engine.

preamble

Entry-point re-exports for the layout manager and frame configurator.