Struct Theme 

pub struct Theme {
    pub light: ColorScheme,
    pub dark: ColorScheme,
    pub type_scale: TypeScale,
    pub shape: ShapeScale,
    pub elevation: Elevation,
    pub motion: MotionScheme,
    pub glass: GlassScale,
    pub brightness: Brightness,
    pub design_language: DesignLanguage,
    pub extensions: ThemeExtensions,
}

The design-token vocabulary: the Theme bundle plus its component token tables, flat-re-exported from frust-theme so app code never names that crate directly. A root component reads the active theme via use_context::<Theme>(); a widget reads it during paint/layout via PaintCtx::theme_as/LayoutCtx::theme_as (or Theme::from_paint_ctx).

Includes the glass material tokens — this crate ships the opaque recipe, and a design system authors its own translucent one over the same types:

use frust::GlassScale;

let glass = GlassScale::opaque_material();
assert_eq!(glass.chrome.blur_radius_intent, 0.0);
assert!(glass.control.is_opaque());

Also the composable-theming surface: ThemeBuilder (defineTheme/copyWith analog), the no-lock-in typed extension slot (ThemeExtensions) plus its first consumer StatusPalette/StatusColors (success/warning/info), and the motion vocabulary (MotionDurations/EasingSet) — all flat-re-exported so an app (or a design-system plugin) authors a theme against frust::* alone. A full design-token bundle: paired light/dark color schemes, the type scale, shape scale, elevation table, and motion scheme, plus which brightness is currently active.

Fields

light: ColorScheme

dark: ColorScheme

type_scale: TypeScale

shape: ShapeScale

elevation: Elevation

motion: MotionScheme

glass: GlassScale

The glass material scale. GlassScale::opaque_material is the only recipe this crate constructs (and what Theme::neutral carries); a design system with translucent chrome supplies its own through ThemeBuilder::glass. Consumed by chrome widgets that branch on GlassMaterial::is_opaque.

brightness: Brightness

design_language: DesignLanguage

extensions: ThemeExtensions

The no-lock-in typed extension slot (a Flutter ThemeExtension analog) — see crate::extensions and Theme::extension. Arc-backed internally, so cloning a Theme (required at both delivery paths — the process-global override slot and the reactive provide_context copy) stays cheap regardless of how many extensions are attached.

Implementations

impl Theme

pub fn neutral() -> Theme

The neutral, design-language-free baseline theme — the only Theme this crate constructs, and the floor every shell falls back to when no design system seeded one via set_default_theme (see docs/ARCHITECTURE.md’s Theme delivery). Material, Cupertino, and Glyph each assemble their own baseline in their own plugin crate.

Composes: a plain grayscale surface/on-surface ramp plus one restrained slate-blue accent (ColorScheme::neutral_light/ColorScheme::neutral_dark); a numeric type scale resolved against a generic system-font stack with no bundled font bytes referenced (TypeScale::neutral); the ShapeScale::neutral/Elevation::neutral value tables — the M3 numbers reused rather than re-authored, since neither is actually M3-branded in value (Elevation::neutral’s own module docs call its shadow math “TUNABLE, not an M3-published spec”, and GlassScale::opaque_material already reuses Elevation::neutral the same way); a no-overshoot MotionScheme::neutral; and GlassScale::opaque_material (already neutral). Attaches StatusPalette::neutral, since success/warning/info are a functional signal, not a design-language “look” — the same reasoning neutral_light/neutral_dark use to keep error real red instead of grayscaling it too.

Starts in Brightness::Light.

Caveat — design_language is DesignLanguage::Material3 here, the derived default, despite this baseline carrying no Material identity: the enum has no neutral variant and is not reshaped by this constructor. Branch on the tokens you actually need, not on this field, when handed a neutral() theme.

Not const: ThemeExtensions’ HashMap construction isn’t const-evaluable.

pub fn scheme(&self) -> &ColorScheme

The active ColorScheme — light or dark, selected by self.brightness.

pub fn with_brightness(self, brightness: Brightness) -> Theme

Force this theme’s Brightness while keeping every other token — a builder over the brightness field, meant to be chained onto a baseline constructor (which hardcodes Brightness::Light) before handing the result to set_app_theme.

Framework footgun this closes: set_app_theme stores its argument as the override-wins theme (the override-wins rule — an app-set theme always beats further OS appearance reports, intentionally). A caller that forces a design language via set_app_theme(some_baseline()) therefore also silently pins brightness to Light forever, discarding whatever OS night-mode state was live a moment before. some_baseline().with_brightness(live) forces the design language without discarding brightness.

pub fn from_paint_ctx<'a>(ctx: &'a PaintCtx<'_>) -> Option<&'a Theme>

Recover the active theme from a widget’s PaintCtx, or None if none was threaded into the paint pass (a supported state — a pre-theme app or a bare-core test).

A one-line convenience wrapper over PaintCtx::theme_as::<Theme>() so a themed widget writes Theme::from_paint_ctx(ctx) in its paint.

pub fn from_layout_ctx<'a>(ctx: &'a LayoutCtx<'_>) -> Option<&'a Theme>

Recover the active theme from a widget’s LayoutCtx, or None if none was threaded into the layout pass. The layout-pass mirror of Theme::from_paint_ctx.

pub fn extension<T>(&self) -> Option<&T>

where T: Any + Send + Sync,

Recover a typed extension previously attached via self.extensions.insert::<T>(..), or None if nothing of that type was ever attached — see crate::extensions’ module docs for the no-lock-in rationale. A one-line convenience wrapper over ThemeExtensions::get.

pub fn builder(base: Theme) -> ThemeBuilder

Start a crate::builder::ThemeBuilder over self as the baseline — the defineTheme/copyWith analog. See crate::builder’s module docs for the full layered-precedence contract (baseline → whole-group swaps → per-token closure edits → extensions).

Trait Implementations

impl Clone for Theme

fn clone(&self) -> Theme

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Theme

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl PartialEq for Theme

fn eq(&self, other: &Theme) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Theme