Working in the notebook¶

What is particular about a viewer that lives inside a notebook: objects can display themselves, a click in the viewer can be read back into Python, and the notebook file remembers what its cells showed.

Auto display¶

Importing jupyter_cadquery in a notebook kernel registers show as the display method of CadQuery's Workplane, Shape, Assembly and Sketch and of build123d's builders (BuildPart, BuildSketch, BuildLine), Shape and ShapeList — the import prints one line per library it took over. From then on an object as the last expression of a cell is shown, into the default sidecar or the cell, without writing show:

from jupyter_cadquery import *

Box(1, 2, 3)          # shown

show with keywords is still there for everything auto display cannot say: names, colors, or any other show keyword. auto_show() does the registration again by hand, for when something else has replaced the display method since — the libraries it covers are the ones installed in the environment, found when jupyter_cadquery was imported.

Reading a pick back into Python¶

A double click on an object in the viewer selects it, and the viewer's last_pick property holds what was hit — the path in the navigation tree and the name. get_pick(assembly, pick) turns that into the CadQuery assembly member behind it:

cv = show(assembly)
# double click a part in the viewer, then:
part = get_pick(assembly, cv.last_pick)

get_pick supports CadQuery assemblies; for anything else the tree path in cv.last_pick["path"] is what you have.

What the notebook remembers¶

A cell viewer is a widget in the cell's output, and JupyterLab can save widget state with the notebook (Settings → Save Widget State Automatically). A notebook saved that way shows its viewers when converted to HTML with jupyter nbconvert --to html, without a kernel — see Export. Without saved state, a reopened notebook shows the pinned PNG of a pinned cell (see pinning) and nothing for an unpinned one until the cell is run again.

A sidecar is not part of the notebook's outputs: it exists while the kernel runs, and a reopened notebook starts without it until the first show.