Struct GeomContext 

pub struct GeomContext<'a> {
    pub panel_rect: Rect,
    pub dpi: f64,
    pub shapes: &'a ShapeRegistry,
    pub scales: &'a dyn ScaleResolver,
    pub projection: &'a Projection,
    pub theme: &'a Theme,
}

Per-draw context passed to Geom::draw. Carries the panel rect (in pixels, output of the composition solver), the dpi, the shape registry, and the channel→scale resolver.

Picking is driven entirely by each geom’s "pick_id" channel: the resolved value is the 24-bit id reported by pick_at. Unset channel → PickId::Skip for the whole geom (no participation in the hitmap); resolved value 0 → PickId::Block (occlude without reporting); otherwise → PickId::Id(value). The context does not allocate or track ids — the user owns the namespace.

Fields

panel_rect: Rect

dpi: f64

shapes: &'a ShapeRegistry

scales: &'a dyn ScaleResolver

projection: &'a Projection

Coordinate projection. Geoms route their final fraction→pixel conversion through Projection::project_to_panel_px so non-Cartesian variants (polar, future ternary) drop in without touching geom code. Defaults to Projection::Cartesian for callers that construct a context via Self::new.

theme: &'a Theme

Effective theme — geoms read defaults (point size, linewidth, fill / stroke style) from theme.geom.* when a channel binding doesn’t supply the value. Defaults to a Theme::default() reference for callers that construct a context via Self::new.

Implementations

impl<'a> GeomContext<'a>

pub fn new( panel_rect: Rect, dpi: f64, shapes: &'a ShapeRegistry, scales: &'a dyn ScaleResolver, ) -> Self

Construct a per-draw context with the default Cartesian projection and default theme. Use Self::with_projection or Self::with_theme to override.

pub fn with_projection( panel_rect: Rect, dpi: f64, shapes: &'a ShapeRegistry, scales: &'a dyn ScaleResolver, projection: &'a Projection, ) -> Self

Construct a per-draw context with an explicit projection. Used by the orchestrator (Plot::draw_panel_into) so the plot’s configured projection threads to every geom.

pub fn with_theme(self, theme: &'a Theme) -> Self

Builder-style override of the context’s theme reference. Returns the context with theme swapped in. Used by the orchestrator to thread the resolved per-plot theme through to every geom’s draw call.

pub fn scale_for(&self, channel: &str) -> Option<&Scale>

Resolve a channel name to a scale, if one is bound.