Drawing a laid-out graph of boxes: swimlane bands, edges (polylines with
an arrowhead, a linetype, a width and an optional label placed clear of
the boxes) and node boxes (a wrapped label, an optional value line,
status badge and sparkline, and an accent bar), as one GGPlot of
ordinary layers.
What a built plot draws, as numbers: per layer (and facet panel) and per
series, how many marks, the x range, the y minimum / maximum and where,
the first and last y, and a band’s extent. A caller that writes about a
chart (a title, an answer) can quote these instead of guessing them.
Convert a polars DataFrame into plot-ready columns using your
crate’s polars (#466): the macro expands in your crate, against the
polars version you depend on, so it works whether you use polars 0.46,
0.52, 0.53 or later — no second polars build, no type mismatch, and
ggplot-rs’s own polars feature can stay off.