Skip to main content

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/open-pencil/open-pencil/llms.txt

Use this file to discover all available pages before exploring further.

​
Core API Overview

The @open-pencil/core package provides the core scene graph, rendering, layout, and Figma-compatible API for OpenPencil.

​
Installation

bun add @open-pencil/core

​
Key Modules

​
SceneGraph

Central data structure for the document tree. Nodes stored in a flat Map<string, SceneNode> with parent-child relationships via parentIndex references. Learn more →

​
SkiaRenderer

CanvasKit-based (Skia WASM) renderer. Renders scene graph to WebGL surface with viewport culling, picture caching, and overlay support. Learn more →

​
Layout (Yoga)

Flexbox layout engine using Yoga WASM. Computes auto-layout (Figma-compatible) for frames with layoutMode !== 'NONE'. Learn more →

​
FigmaAPI

Figma Plugin API-compatible interface for scripting and tools. Wraps SceneGraph with a proxy-based API matching figma.* global. Learn more →

​
Architecture

  • Zero DOM dependencies: Runs headless in Node.js/Bun
  • Flat node storage: Map<string, SceneNode> for O(1) lookups
  • Immutable-style updates: graph.updateNode(id, changes) invalidates caches
  • Picture caching: Pre-render nodes with effects/shadows, skip re-render on pan/zoom

​
Usage Example

import { SceneGraph, SkiaRenderer, FigmaAPI, computeAllLayouts } from '@open-pencil/core'
import { getCanvasKit } from '@open-pencil/core'

const ck = await getCanvasKit()
const canvas = document.getElementById('canvas') as HTMLCanvasElement
const surface = ck.MakeWebGLCanvasSurface(canvas)!

// Create scene
const graph = new SceneGraph()
const page = graph.getPages()[0]
const frame = graph.createNode('FRAME', page.id, {
  x: 100,
  y: 100,
  width: 200,
  height: 100,
  fills: [{ type: 'SOLID', color: { r: 0.2, g: 0.4, b: 0.8 }, opacity: 1, visible: true }]
})

// Compute layout
computeAllLayouts(graph)

// Render
const renderer = new SkiaRenderer(ck, surface)
renderer.pageId = page.id
renderer.render(graph, new Set(), {})

// Use FigmaAPI
const figma = new FigmaAPI(graph)
const rect = figma.createRectangle()
rect.resize(100, 100)
rect.fills = [{ type: 'SOLID', color: { r: 1, g: 0, b: 0 }, opacity: 1, visible: true }]
figma.currentPage.appendChild(rect)

​
Type Definitions

export type NodeType =
  | 'CANVAS'
  | 'FRAME'
  | 'RECTANGLE'
  | 'ELLIPSE'
  | 'TEXT'
  | 'LINE'
  | 'STAR'
  | 'POLYGON'
  | 'VECTOR'
  | 'GROUP'
  | 'SECTION'
  | 'COMPONENT'
  | 'COMPONENT_SET'
  | 'INSTANCE'
  | 'CONNECTOR'
  | 'SHAPE_WITH_TEXT'

export interface SceneNode {
  id: string
  type: NodeType
  name: string
  parentId: string | null
  childIds: string[]
  x: number
  y: number
  width: number
  height: number
  rotation: number
  fills: Fill[]
  strokes: Stroke[]
  effects: Effect[]
  opacity: number
  visible: boolean
  locked: boolean
  // ... 50+ more properties
}

​
Next Steps

Build docs developers (and LLMs) love

Get started for freeTalk to us