A browser-based canvas editor for Adafruit IO Marquee e-ink displays. It turns what you draw into epaper-ready bitmaps entirely in the browser and publishes them to Adafruit IO feeds. It is a static site: no server, no build step, and everything it remembers lives in your browser's localStorage.
- Browser must be capable of Web Serial (Chrome, Edge, Firefox)
There is nothing to install, this repo has no runtime or dev dependencies.
Bring up Marquee Web:
git clone https://github.com/adafruit/Marquee_Web.git
cd Marquee_Web
npm startEverything you draw on the canvas is rendered, dithered, palette-remapped by
public/js/canvas/bitmap.js.
bitmap.js is a pure-JS port of a subset of the ImageMagick CI pipeline and implements the following magick (ImageMagick) command only:
magick in.png -dither FloydSteinberg -define dither:diffusion-amount=N% \
-remap eink-<type>.png gif:- | magick gif:- -compress none BMP3:-
Your Adafruit IO Key and Wi-Fi credentials are stored in your browser's localStorage and written to the hardware's USB MSC volume.
MIT — see LICENSE. Copyright (c) 2026 Adafruit Industries.