Rendering

Headless rendering of SysML diagrams to SVG/PNG.

The interactive widgets (longeron.diagrams) lay themselves out in the browser. This module runs the same layout engine – elkjs 0.9.3, vendored as _js/elk.bundled.js (EPL-2.0) – in a node subprocess instead, then draws the result as styled SVG:

from longeron import diagrams, render

render.to_svg(diagrams.state_diagram(machine), “machine.svg”) render.to_png(model, “model.png”) # builds a view automatically

PNG conversion uses cairosvg when available (pixi environments include it). Label sizes are estimated (the browser pipeline measures real glyphs), so proportions differ slightly from the live widget.

longeron.render.layout(elk_json)

Run the vendored elkjs on an ELK JSON graph and return the layout.

Return type:

dict

longeron.render.to_svg(source, path=None)

Render a diagram (widget, ipyelk node, or model element) to SVG.

Return type:

str

longeron.render.to_png(source, path, scale=2.0)

Render a diagram to PNG (requires cairosvg).

Return type:

Path