Files
vectorcraft/crates/cad
dotCooCoo 74ea25cd6c File formats: HP-GL (.plt) plot files open and place
File › Open and File › Place refused plotter files: HP-GL/2 files
(.plt, .hpgl, .hgl, .hpg) were not a format VectorCraft reads.

The format table gets a read-only HP-GL format, read by a new
vectorcraft_cad::hpgl module. Each line the pen draws becomes a stroked
path in its pen's color and width, with the line type as a dash pattern
and the line attributes as caps and joins. Circles, arcs, wedges and
Bézier curves are drawn as curves. Filled and edged rectangles, wedges
and polygons (polygon mode) become filled or stroked paths, and encoded
polylines, scaling points, user units and rotation are read. Plotter
units (1016 to the inch, y up) become points, and the artboard holds
what the art paints. Place brings the art in as one group. Older HP-GL
files are read by the HP-GL/2 rules for the instructions the two share.

A file is recognized by its first instructions, after any printer
escape sequences and PJL lines, so a plot file also opens under an
extension no other format reads. VectorCraft's own rules where the
device decides: before the first SP the pen is pen 1, and the hard-clip
limits are 11 x 8.5 in, which P2 takes when the file sets no scaling
points. Labels, symbol-mode symbols and raster images are not drawn,
the input window does not clip, hatched fills are filled solid, and
later pages are drawn over the first; the warnings list each. Objects,
path points and pen widths are capped, and the import fuzzer covers
random, mutated and garbage plot files.

An importer plug-in that lists .plt, .hpgl, .hgl or .hpg now opens
those files only when document.open names it with `importer`.

Docs: docs/mcp.md, docs/file-format-parity.md,
docs/target-app-parity.md, docs/releasing.md.
2026-11-11 16:03:41 -08:00
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