@hfu.digital/boardkit-core

Zero-dependency shared kernel for BoardKit. Contains types, scene graph, drawing tools, collaboration protocol, and validation — all in pure TypeScript with no runtime dependencies.

Installation

bun add @hfu.digital/boardkit-core

What's Included

Types

The Element discriminated union covers all whiteboard element types:

import type { Element, StrokeElement, ShapeElement, TextElement } from '@hfu.digital/boardkit-core';
import type { Board, Page, Participant } from '@hfu.digital/boardkit-core';
import type { ClientMessage, ServerMessage } from '@hfu.digital/boardkit-core';

Scene Graph

Immutable state container for elements:

import { createScene, addElement, removeElement, updateElement, getElementsByPage } from '@hfu.digital/boardkit-core';

let scene = createScene();
scene = addElement(scene, myElement);
scene = updateElement(scene, 'el-1', { zIndex: 10 });
const pageElements = getElementsByPage(scene, 'page-1');

Tools

Abstract Tool class with state machine (idle → active → finishing → idle). Nine tools available via ToolRegistry:

import { ToolRegistry, TOOL_IDS } from '@hfu.digital/boardkit-core';

const registry = ToolRegistry.createDefault();
const pen = registry.get(TOOL_IDS.PEN);

| Tool | TOOL_IDS | Creates | |------|----------|---------| | PenTool | PEN | StrokeElement | | ShapeTool | SHAPE | ShapeElement | | TextTool | TEXT | TextElement | | StickyNoteTool | STICKY_NOTE | StickyNoteElement | | ConnectorTool | CONNECTOR | ConnectorElement | | SelectTool | SELECT | — (selection/drag) | | EraserTool | ERASER | — (delete mutations) | | LaserTool | LASER | — (preview only) | | HandTool | HAND | — (viewport pan) |

Operations

• LWW Merge: mergeElement() / mergeScene() for conflict resolution (remote wins on tie)
• History: Undo/redo stack with configurable max depth
• Clipboard: Serialize/deserialize selections with relative positioning
• Transforms: Move, resize, rotate elements

Drawing Algorithms

• Smoothing: Catmull-Rom spline interpolation
• Simplification: Ramer-Douglas-Peucker algorithm
• Pressure: Pen pressure to stroke width mapping

Validation

import { validateElement, validateBoardLimits, validateAssetSize } from '@hfu.digital/boardkit-core';

const result = validateElement(untrustedData);
if (!result.valid) console.error(result.errors);

License

MIT