incular-config

Architecture and support

Renderer-independent configuration values shared across Incular layers.

This crate owns box constraints, physical edge insets, axis and direction values, and alignment/flex/wrap policy enums. It depends only on incular-core geometry, so layout, widgets, runtime, and platform adapters can exchange these values without depending on one another. It deliberately owns no layout algorithms, widget state, renderer state, or platform handles. RuntimeEnvironment keeps ordered locale preferences as ICU4X Locale values, not raw strings. Platform adapters must parse external locale input before publishing an environment update; widgets receive the parsed values through the runtime.

ICU4X uses its compiled_data strategy for Incular's direct Unicode services. That keeps the initial runtime self-contained; custom data providers remain an advanced future integration point rather than framework infrastructure.

LocaleResolver applies ICU4X locale fallback and script directionality to application-declared LocalizationCatalog resources. It also provides framework-neutral integer/date formatting and ICU cardinal-plural selection through PluralForms. The catalog owns messages and any message-template syntax; Incular does not impose a translation file format or load application resources at runtime.

ApplicationDefaults and WidgetDefaults are the shared default contract. Window/environment constructors, plain text, and sliver-backed widgets consume these values rather than maintaining independent copies. A base container does not acquire a background from this contract: transparent/no-paint is the neutral widget default, and visible surfaces belong to an explicit root widget or design-system theme.

TransparencyMode is the renderer-independent native presentation intent. It is intentionally separate from background_color: framebuffer alpha determines how the operating-system compositor treats a window, while the background color is the base color underneath the rendered scene. Either value can be changed without implying the other. Platform and renderer crates carry the same typed transparency value instead of maintaining parallel booleans or renderer-specific forms.

WindowSizePolicy makes native size ownership explicit. Viewport keeps the ordinary desktop contract where native metrics tightly constrain the retained root. Content is opt-in for compact utility/popup-style windows: the declared initial size remains a stable minimum, the retained root layout can request a larger native host, and the host shrinks back when primary content becomes smaller. Paint-only overflow, shadows, filters, and transient portals do not participate in top-level sizing. Decoration is deliberately unrelated to this policy; an undecorated window is not implicitly content-sized.

TransientPresentation is orthogonal again: Auto lets a capable platform host lift menus/popovers/tooltips into a transient surface and otherwise keeps them in the owning view's overlay, while Overlay explicitly requests the in-view representation. This policy never implies a top-level resize.