$ show evolus/pencil
Pencil is an open-source GUI prototyping tool for creating wireframes and mockups across platforms. It is built as an Electron desktop application with a custom UI framework that includes a canvas for SVG-based shape editing, a stencil/collection system for reusable UI components, and export pipelines to SVG, PDF, ODT, HTML, and PNG. The architecture is a monolith with a main process (app/index.js) managing windows and IPC, and a renderer process handling the UI and canvas interactions. The codebase shows a migration from legacy Mozilla XULRunner to Electron, resulting in a mix of old XUL/XPCOM code and modern JavaScript/Node.js patterns. Key data flows involve loading shape definitions from XML collections, manipulating shapes on an SVG canvas, and serializing documents to custom archive formats (.ep, .epz, .epgz). External dependencies include Electron, various npm packages (adm-zip, archiver, jimp, perfect-freehand), and system fonts. The repository also contains a web-based asset management subsystem (DataTable, MapView) that appears to be a separate concern embedded within the same codebase.
The LLM identified 4 files worth highlighting for reuse:
A simple, self-contained async task queue that executes functions sequentially. It uses a callback-based pattern with no external dependencies, making it easily extractable for any project needing ordered asynchronous execution.
Part of a well-defined property type system that implements fromString/toString methods for serialization. The Bool type is a standalone value object with no internal dependencies, demonstrating a clean pattern for type conversion that can be reused in other applications needing typed property handling.
Contains the ResizeSensor class, a standalone dimension change detection mechanism that uses a hidden iframe to observe element size changes. It is self-contained and can be extracted for any project requiring responsive layout updates without polling.
A collection of cross-browser DOM manipulation helpers including XPath evaluation, namespace-aware element creation, and event handling. It is self-contained and provides a consistent API that can be reused in projects needing to work with XML/SVG namespaces.