Created by Jürg Lehni & Jonathan Puckey, Paper.js is an open source vector graphics scripting framework that runs on top of the HTML5 Canvas. It offers a clean Scene Graph / Document Object Model and a lot of powerful functionality to create and work with vector graphics and bezier curves

Paper.js is based on and largely compatible with Scriptographer, a scripting environment for Adobe Illustrator, originally developed by Jürg and Jonathan and with more than 10 years of development.

Feature overview :

• A Scene Graph / Document Object Model for vector graphics: Work with nested layers, groups, paths, compound paths, rasters, symbols etc.
• The handling and drawing of these graphic items is automatic and optimised, allowing you to construct or modify your items and styles and leave the drawing commands to Paper.js.
• A well designed and battle hardened Programming Interface.
• There is a good reason for the word Vector in Vector Graphics. Paper.js offers best of breed Vector Mathematics through its core types such as Point, Sizeand Rectangle.
• PaperScript, a simple extension of JavaScript allows the scoped execution of scripts without polluting the global scope, the execution of multiple scripts per page in their separate sand-boxed scopes while sharing the library code, and the manipulation of Point and Size objects using direct math operations as if they were plain numbers.
• Simple, yet elaborate mouse and keyboard interaction.
• Construct paths and manipulate their curves and segments in very convenient ways.
• Inspect and manipulate the precise bounding box of any item, supporting complicated stroke styles with square ends and miter limits.
• Smoothen curves, simplify path segments by fitting curves through points.
• Simulate dashed strokes which are currently lacking from the Canvas object, at near native drawing speed.

For more information see paperjs.org