cad-easy-font 0.1.0

DXF text and AutoCAD SHX/BigFont support implemented with Rust and PyO3.

easy-font

easy-font is a PyO3/Rust Python extension focused on DXF text handling and AutoCAD SHX font compatibility. It intentionally starts smaller than ezdxf: the first milestone is reliable text/style extraction plus support for AutoCAD-86 SHX unifont and bigfont files found in CAD datasets.

Development

nix-shell
maturin develop
pytest

Python API

import easy_font as cad

font = cad.open_shx("cad-data/fonts/hztxt.shx", encoding="gbk")
print(font.kind, font.is_bigfont, font.glyph_count)

doc = cad.readfile("cad-data/data/hatch.dxf")
for entity in doc.modelspace():
    if entity.dxftype == "TEXT":
        print(entity.text)

dwg = cad.readfile("cad-data/data/baseline-sample.dwg")
print(dwg.format, len(dwg.modelspace()))

# Resolve extracted text to local font files.
resolved_rows = cad.resolve_text_runs(dwg, ["cad-data/fonts"])
print(resolved_rows[0]["style"], resolved_rows[0]["font_path"])

Current scope

• Reads ASCII DXF group-code pairs.
• Reads DWG files using a handwritten Rust binary parser path.
• Extracts STYLE table records, including primary SHX font and BigFont file.
• Extracts common text entities from ENTITIES: TEXT, MTEXT, ATTRIB, and ATTDEF.
• Recognizes AutoCAD-86 SHX unifont and bigfont headers.
• Preserves raw SHX glyph records so BigFont files that ezdxf cannot load are still inspectable.
• Decodes DXF text escapes such as %%d, \P, and \U+4E2D.
• Decodes encoded BigFont text bytes through Python codecs such as gbk, big5, and shift_jis.

Full DXF entity parity with ezdxf is out of scope for this initial implementation.

Font Resolution Workflow

python scripts/extract_and_resolve_fonts.py --input baseline-sample.dwg --limit 10

This script reads text entities from a drawing, resolves style fonts against cad-data/fonts, and prints style/text font coverage. For SHX fonts it verifies glyph coverage through open_shx; for TTF/OTF/TTC/WOFF it verifies cmap coverage when fontTools is available.

To validate real render output for SFNT fonts (TTF/OTF/TTC/WOFF/WOFF2) and save PNG previews:

python scripts/validate_render_output.py --input baseline-sample.dwg --max-rows 200 --preview-limit 20