Expand description
Deterministic fit-to-container and font metric lifecycle.
This module provides the infrastructure for mapping pixel-space container dimensions to cell-grid dimensions, accounting for DPR, zoom, and font metrics. It ensures that equivalent resize/font-load event streams yield identical viewport and cursor geometry outcomes.
§Key types
CellMetrics: cell size in sub-pixel units (1/256 px), deterministic.ContainerViewport: container dimensions with DPR and zoom tracking.FitPolicy: strategy for computing grid dimensions from container.FitResult: computed grid dimensions from a fit operation.MetricGeneration: monotonic counter for cache invalidation.MetricInvalidation: reason for metric recomputation.MetricLifecycle: stateful tracker for font metric changes.
§Determinism
All pixel-to-cell conversions use fixed-point arithmetic (256 sub-pixel units per pixel) to avoid floating-point rounding ambiguity across platforms. The same inputs always produce the same grid dimensions.
Structs§
- Cell
Metrics - Cell dimensions in sub-pixel units (1/256 px) for deterministic layout.
- Container
Viewport - Container dimensions and display parameters for fit computation.
- FitResult
- Computed grid dimensions from a fit operation.
- Metric
Generation - Monotonic generation counter for metric cache invalidation.
- Metric
Lifecycle - Stateful tracker for font metric changes and cache invalidation.
- Metric
Snapshot - Diagnostic snapshot of metric lifecycle state.
Enums§
- FitError
- Errors from fit computation.
- FitPolicy
- Strategy for computing grid dimensions from container and font metrics.
- Metric
Invalidation - Reason for a font metric recomputation.
Functions§
- fit_
to_ container - Compute grid dimensions by fitting cells into a container viewport.