@osdlabel/decoration

Declarative annotation decorations (text labels, computed measurements, connector lines) and calibrated geometry math for osdlabel, a web-based image annotation library for gigapixel/DZI images.

Decorations are a pure derivation of annotation state — they are never serialized, and they are recomputed whenever the underlying annotations change. This package defines the data model and provider contract; the rendering happens in @osdlabel/fabric-osd. Zero framework dependencies. Depends on @osdlabel/annotation, @osdlabel/geometry, and @osdlabel/viewer-api.

Installation

npm install @osdlabel/decoration

What's inside

• Decoration discriminated union — TextDecoration (supports zIndex), LineDecoration, and DomDecoration
• DecorationProvider contract + composeProviders, DecorationContext
• Built-in providers: createMeasurementProvider, createLabelProvider, createDistanceProvider
• withSelectionEmphasis — opt-in style/z-index elevation for the selected annotation's decorations
• Measurements: Measurement, measureDistance, measureLength, measurePerimeter (per-axis, correct on anisotropic images), toPhysicalLength, toPhysicalArea, formatMeasurement
• Geometry math — area, perimeter, length, radius, distance, centroid, midpoint, boundingBox, circleToBoundingRectangle — now lives in @osdlabel/geometry and is re-exported here unchanged

Usage

import {
  createLabelProvider,
  createMeasurementProvider,
  composeProviders,
} from '@osdlabel/decoration';

// composeProviders takes an array; createMeasurementProvider needs an options
// object saying which measurements to render (all flags default to false).
const providers = composeProviders([
  createLabelProvider(),
  createMeasurementProvider({ area: true, perimeter: true, length: true, radius: true }),
]);

License

BSD-3-Clause. Part of the osdlabel monorepo.