ocp-viewer-core

The shared half of the OCP viewer ecosystem: one show suite, one tessellation, one set of config semantics, used by four viewers that each keep their own transport and their own settings storage.

• ocp_vscode — the VS Code extension and its Python client
• ocp_viewer — the standalone viewer, python -m ocp_viewer
• Jupyter CadQuery — through cad-viewer-widget
• build123d Studio

Published as one project under one version to two registries: ocp-viewer-core on PyPI for the Python half, ocp-viewer-core on npm for the JavaScript half. The two are shipped and versioned together, so which version of the pair a host has is one question rather than two.

The idea

Each host provides a Comms — a Python encoder and a JavaScript decoder, shipped as a pair — and a settings source. Everything above that is shared and knows nothing about which host it is running in. No host is nameable inside this package: no port=/viewer= pairs, no is_jupyter_cadquery, no environment sniffing, and no host name in a string. A conformance kit enforces that by running the shared half end to end over an in-memory loopback with no host at all.

Per-host imports stay per host: from ocp_vscode import show beside from build123d_studio import show. A single universal import with the host discovered at runtime is deliberately not offered — it is how a show() once silently drew into somebody else's viewer.

Status

Early development. Nothing here is published, and the API changes without notice until the first host adopts it.

Layout

ocp_viewer_core/__init__.py is import-free by design: hosts import the submodule they need, so that importing the package never pulls in the tessellator or OCP.

Use

ocp vscode:

A host writes one class and supplies one list. exclude_keys names the keywords it may not be told, because its surface decides them - the show signature is the superset of every host's, so a keyword one host owns is a keyword another has to refuse by name rather than ignore.

comms = MyComms()
session = Session(comms)                        # sets session cache to None
config = Config(session, ("cad_width", "height"))
show(objects)

What a host persists between sessions is its own business and needs no key list here: it answers with values, from Comms.workspace_config(). Which of the viewer's reported state counts as configuration - and so survives into the next show - is keys.CONFIG, derived from the vocabulary, because that set is a property of three-cad-viewer's state and not of any host's settings.

Dependencies

ocp-tessellate for tessellation, and three-cad-viewer as a peer dependency of the JavaScript half. No OCP provider is declared — the same OCP namespace is supplied by cadquery_ocp, cadquery_ocp_novtk and conda's OCP, and naming one would break users of the other two. The host or the user chooses.

Licence

Apache-2.0.