ezjww

ezjww is a JWW parser and DXF conversion library. The core parser/writer is implemented in Rust and exposed to Python with PyO3.

Current Features

• Validate and parse .jww files by their JwwData. binary signature.
• Report structured CP932 replacement diagnostics with source byte offsets.
• Read JWW files written by Jw_cad 8 (version 700, Unicode builds): CStrings with the MFC FF FE FF marker are decoded as UTF-16LE, and block definitions (whose list count is a WORD) are loaded.
• Read damaged files best-effort: a main entity list that cannot be read to its end keeps the entities parsed so far and reports ENTITY_LIST_TRUNCATED (see docs/DIAGNOSTICS.md); MFC CArchive escaped counts (65535+ entities), NULL tags and big object tags are honoured.
• Read document/header data from Python.
• Convert parsed JWW entities to DXF intermediate entities.
• Write ASCII DXF files.
• Emit DXF handles, BLOCK_RECORD table, and OBJECTS section for better CAD compatibility.

Installation

Install the package from PyPI:

pip install ezjww

If you want to use the optional plotting feature, install the package with the plot extra:

pip install "ezjww[plot]"

Install the package from source:

git clone https://github.com/neka-nat/ezjww.git
cd ezjww
uv sync

Python API

from ezjww import (
    ALL_ISSUE_CODES,
    audit,
    bbox,
    is_jww_file,
    readfile,
    plot_jww,
    read_document,
    read_dxf_document,
    report,
    stats,
    to_dxf_string,
    write_dxf,
)

ok = is_jww_file("sample.jww")
doc = read_document("sample.jww")
dxf_doc = read_dxf_document("sample.jww")
dxf_text = to_dxf_string("sample.jww")
write_dxf("sample.jww", "sample.dxf")
plot_jww("sample.jww", save_path="sample.png")

drawing = readfile("sample.jww")
msp = drawing.modelspace()
lines = msp.query("LINE", layer="#lv4")
mix = msp.query('LINE POINT[layer=="#lv4", color==5]')  # ezdxf-like selector
extents = drawing.bbox(explode_inserts=True)
raw_dxf = drawing.to_dxf_string()
dist = drawing.stats()
health = drawing.audit()  # or: audit("sample.jww")
for diagnostic in health["diagnostics"]:
    print(diagnostic["code"], diagnostic["details"])

# Stable machine-readable catalog for integrations and CI.
assert set(health["issue_codes"]) <= set(ALL_ISSUE_CODES)
full = report("sample.jww", explode_inserts=True)

# expand INSERT references (nested block aware)
flat = drawing.to_dxf(explode_inserts=True, max_block_nesting=32)
flat_count = len(flat["entities"])
# max_block_nesting must be >= 1

CLI

The package installs the ezjww command.

# show summary
ezjww info jww_samples/Test1.jww

# run health checks
ezjww audit jww_samples/Test1.jww --json

# calculate drawing extents
ezjww bbox jww_samples/Test1.jww --json --explode-inserts

# show entity distribution
ezjww stats jww_samples/Test1.jww --json

# show combined audit+bbox+stats
ezjww report jww_samples/Test1.jww --json --explode-inserts

# convert one file
ezjww to-dxf jww_samples/Test1.jww -o /tmp/Test1.dxf

# convert one file + JSON report
ezjww to-dxf jww_samples/Test1.jww -o /tmp/Test1.dxf --report json

# convert one file with INSERT expansion
ezjww to-dxf jww_samples/Test1.jww -o /tmp/Test1.dxf --explode-inserts

# convert directory (recursive)
ezjww to-dxf-dir jww_samples -o /tmp/dxf_out -r

# render with matplotlib
ezjww plot jww_samples/Test1.jww -o /tmp/Test1.png --explode-inserts

Public contracts

• Audit issue code catalog and stability policy
• JWW binary signature specification

is_jww_file(path) checks file content, not the filename extension. A matching signature is only a lightweight format check; parsing still validates the remaining structure.

Development

cargo fmt --all
cargo test
maturin develop