Remote framebuffer in a notebook (anywidget)¶

pdum.rfb renders in Python and views in the browser over a plain WebSocket — not the Jupyter kernel comm, so frames never touch the notebook protocol. This works the same in Jupyter and marimo (mo.ui.anywidget(RfbViewer(...))). Install the extra: uv add 'habemus-papadum-rfb[anywidget]'.

One widget = one Web Worker + one WebSocket; the server multiplexes many streams on one port. See docs/notebook.md.

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import itertools

import numpy as np

import pdum.rfb as rfb
from pdum.rfb.notebook import publish_loop

# `await` works at the top level in Jupyter/marimo (a loop is already running).
display = await rfb.serve(320, 240, port=0)
frames = itertools.count()


def render():
    t = next(frames) % 256
    img = np.zeros((240, 320, 3), dtype=np.uint8)
    img[:, :, 2] = t  # animate the blue channel
    img[100:140, :] = (240, 120, 40)  # a static orange band
    return img


# Non-blocking background task on the notebook's loop.
task = publish_loop(display, render, fps=10)
print("serving at", display.ws_url)

import itertools import numpy as np import pdum.rfb as rfb from pdum.rfb.notebook import publish_loop # `await` works at the top level in Jupyter/marimo (a loop is already running). display = await rfb.serve(320, 240, port=0) frames = itertools.count() def render(): t = next(frames) % 256 img = np.zeros((240, 320, 3), dtype=np.uint8) img[:, :, 2] = t # animate the blue channel img[100:140, :] = (240, 120, 40) # a static orange band return img # Non-blocking background task on the notebook's loop. task = publish_loop(display, render, fps=10) print("serving at", display.ws_url)

Render the batteries viewer right in the cell (status pill, HUD toggle, toolbar):

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display.widget()

display.widget()

Or a bare canvas on the same stream — you supply the chrome/styling:

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display.widget(batteries=False)

display.widget(batteries=False)

Tear down when done:

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task.cancel()
await display.aclose()

task.cancel() await display.aclose()