ezdwg

DWG (R13-R2018 / AC1012-AC1032) reader with a Python API inspired by ezdxf. This project is a DWG read-focused parser with growing high-level entity coverage while providing a native AC1015 writer for basic entities and nested blocks.

Documentation: https://monozukuri-ai.github.io/ezdwg/

Status

• High-level API (ezdwg.read): R13 / AC1012 and R14 / AC1014 (2D entities), R2000 / AC1015, R2004 / AC1018, R2007 / AC1021, R2010 / AC1024, R2013 / AC1027, R2018 / AC1032
• Raw API (ezdwg.raw): the same versions, with the per-type decode_* functions and the table, style and placement functions
• High-level entities include LINE, ARC, LWPOLYLINE, POINT, CIRCLE, ELLIPSE, TEXT, MTEXT, DIMENSION, INSERT/MINSERT, HATCH, and SPLINE
• Raw API exposes the corresponding entity decoders plus low-level POLYLINE/VERTEX helpers
• Output units/angles: high-level API returns ARC angles in degrees

Install

Install from PyPI:

pip install ezdwg

Plotting (optional):

pip install "ezdwg[plot]"

DWG to DXF conversion (optional, ezdxf backend):

pip install "ezdwg[dxf]"

If you want to contribute or develop locally, you can install from source: Rust toolchain is required (PyO3 build).

git clone https://github.com/monozukuri-ai/ezdwg.git
cd ezdwg
maturin develop
pip install -e .

For release version updates, run uv run scripts/bump_version.py <version>. The root Cargo.toml is the single version source for Rust and Python; the command refreshes the lock files. See Releasing for details.

Quick Start

import ezdwg

doc = ezdwg.read("path/to/file.dwg")
msp = doc.modelspace()

for e in msp.query(
    "LINE LWPOLYLINE ARC CIRCLE ELLIPSE POINT TEXT MTEXT "
    "DIMENSION INSERT MINSERT HATCH SPLINE"
):
    print(e.dxftype, e.handle, e.dxf)

doc.modelspace() yields only model-space entities (block-definition contents and paper-space entities are excluded via each entity's stored placement); doc.paperspace() yields paper-space entities and doc.entities() everything in the file, with e.dxf["owner_handle"] / doc.entity_placement(handle) to partition them yourself.

Layouts and viewports:

import ezdwg

doc = ezdwg.read("path/to/file.dwg")
for name, layout in doc.layouts().items():
    print(name, layout["model"], layout["active"], layout["paper_width"], layout["paper_height"])

for viewport in doc.paperspace().query("VIEWPORT"):
    dxf = viewport.dxf
    scale = dxf["height"] / dxf["view_height"]  # R2000+; the first viewport of a sheet is the sheet itself

Drawing units and header variables:

import ezdwg

doc = ezdwg.read("path/to/file.dwg")
doc.units                        # "millimeters" ($INSUNITS; None for R14)
doc.header_variables()["extmin"]  # model-space extents, unit formats, ...

Plot in matplotlib:

import ezdwg

doc = ezdwg.read("path/to/file.dwg")
doc.plot()

CLI

uvx ezdwg --version
uvx ezdwg inspect examples/data/line_2000.dwg
uvx ezdwg inspect examples/data/line_2000.dwg --verbose
uvx --from "ezdwg[plot]" ezdwg plot examples/data/line_2000.dwg
uvx --from "ezdwg[plot]" ezdwg plot examples/data/line_2000.dwg -o /tmp/line_2000.png --dpi 200
uvx --from "ezdwg[dxf]" ezdwg convert examples/data/line_2000.dwg /tmp/line_2000_out.dxf
uvx --from "ezdwg[dxf]" ezdwg convert examples/data/arc_2000.dwg /tmp/arc_2000_out.dxf --types "ARC" --dxf-version R2010
uvx ezdwg write examples/data/line_2000.dwg /tmp/line_2000_out.dwg --types "LINE" --dwg-version AC1015

plot displays model-space entities in a matplotlib window, or opens an SVG preview in your browser when no interactive backend is available. Use -o / --output to save a PNG, SVG, or PDF without opening a viewer; --types and --title filter entities and set the title. For local development, run uv run --extra plot ezdwg plot path/to/file.dwg.

DWG to DXF

ezdxf is used as the DXF writing backend.

import ezdwg

result = ezdwg.to_dxf(
    "examples/data/line_2000.dwg",
    "/tmp/line_2000_out.dxf",
    types="LINE ARC LWPOLYLINE",
    dxf_version="R2010",
)
print(result)

Or from an already opened document/layout:

doc = ezdwg.read("examples/data/line_2000.dwg")
doc.export_dxf("/tmp/line_2000_out.dxf")

DWG to DWG (Native AC1015 Writer)

import ezdwg

result = ezdwg.to_dwg(
    "examples/data/line_2000.dwg",
    "/tmp/line_2000_rewrite.dwg",
    version="AC1015",
)
print(result)

Or from an already opened document/layout:

doc = ezdwg.read("examples/data/line_2000.dwg")
doc.export_dwg("/tmp/line_2000_rewrite.dwg", version="AC1015")

Path/Document exports select model space. Use strict=True to reject unsupported or undecoded entities and detected attribute loss before writing. Otherwise inspect result.skipped_by_type and result.diagnostics. Referenced layers, simple line patterns, basic text styles, Japanese text, units and placement attributes are preserved. Referenced blocks and attached attributes are kept as a graph. Complete source document metadata remains outside the scope. See native writer scope and external checks.

Create and Edit DWG

import ezdwg

drawing = ezdwg.new()  # AC1015, no input file needed
msp = drawing.modelspace()
line = msp.add_line((0, 0), (10, 5), color_index=1)
msp.update(line, end=(20, 5))
drawing.save("created.dwg")  # strict validation by default

edited = ezdwg.read("created.dwg").edit()
edited.modelspace().add_circle((5, 5), radius=2)
edited.save("edited.dwg")

The editable snapshot supports basic entities, block definitions, nested INSERTs and single-line ATTDEF/ATTRIB attributes. Queries return live entities; use update(), mutate entity.dxf, or call delete(entity). Saving validates the drawing, writes a temporary sibling file, and atomically replaces the destination. See the editing guide for table editing, import limitations and diagnostics.

Blocks use the same geometry methods in local coordinates:

part = drawing.blocks.new("Part", base_point=(0, 0, 0))
part.add_circle((0, 0), radius=2)
part.add_attdef("ID", "default", insert=(0, 3), height=1)
ref = msp.add_blockref("Part", insert=(10, 20), rotation=30)
msp.add_attrib(ref, "ID", "P-001", insert=(10, 23), height=1)
drawing.save("blocks.dwg")

Attribute placement is explicit; add_attrib does not automatically transform an ATTDEF or synchronize defaults. See blocks and attributes.

Paper space is a single layout (Layout1) with a sheet in millimetres and viewports that show model space at a scale; view_height / height is the scale denominator, so an A3 sheet plotted 1:1 shows the model at 1:100 here:

drawing.set_paper(420, 297)  # ISO A3 landscape, margins (left, bottom, right, top) optional
psp = drawing.paperspace()
psp.add_viewport((210, 148.5), 400, 277, view_center=(10000, 5000), view_height=277 * 100)
psp.add_text("A3 1:100", (10, 5), height=5)  # title block entities live on the sheet
drawing.save("sheet.dwg")

The sheet's own viewport is written automatically in front of the user viewports.

Examples

Sample DWG files are available under examples/data/.

python examples/basic_read.py
python examples/query_types.py
python examples/plot.py
python examples/text_mtext.py
python examples/dimensions.py
python examples/raw_insert_2004.py
python examples/convert_to_dxf.py

Low-Level API

If you need raw decode access:

from ezdwg import raw

raw.decode_line_entities("path/to/file.dwg")

Limitations

• Native DWG write currently targets AC1015 only
• Native DWG write supports a subset of entities: LINE/RAY/XLINE/POINT/ARC/CIRCLE/ELLIPSE/SPLINE/SOLID/TRACE/3DFACE/LWPOLYLINE/POLYLINE_2D/POLYLINE_3D/TEXT/MTEXT/INSERT/ATTDEF/ATTRIB/HATCH/DIMENSION/IMAGE/VIEWPORT, including nested block definitions, rendered dimension blocks, raster image definitions and one paper-space layout (Drawing.paperspace(), Drawing.set_paper()); true colours are rounded to the nearest ACI
• Paper space of an existing drawing is not imported by Document.edit() / to_dwg; only new paper-space content is written
• High-level API supports R13 (AC1012, experimental), R14 (AC1014, experimental), R2000 (AC1015), R2004 (AC1018), R2007 (AC1021), R2010 (AC1024), R2013 (AC1027), and R2018 (AC1032)
• AC1012/AC1014 decode the 2D entity types with the layouts of the ODA specification (LINE, ARC, CIRCLE, ELLIPSE, POINT, LWPOLYLINE, POLYLINE_2D, TEXT, MTEXT, ATTRIB/ATTDEF, INSERT/MINSERT, HATCH, SOLID, TRACE, 3DFACE, SPLINE, LEADER, TOLERANCE, MLINE, SHAPE, DIMENSION), with block membership, block names and dimension blocks, and the 3D polylines and meshes. R13/R14 have no lineweights and no layer plot flag, and their viewports state a window but no view
• AC1021/AC1024/AC1027/AC1032 use native decode for LINE/ARC/LWPOLYLINE/POINT/CIRCLE/ELLIPSE and are regression-tested against paired DXF samples
• TEXT/MTEXT/ATTRIB/ATTDEF of R2007 and later are read from the string stream of the object and regression-tested on one drawing saved in every version (R14 to R2018)
• AC1021/AC1024/AC1027/AC1032 entity style/layer color resolution is currently best-effort on some files
• Ordinary legacy 2D/3D polylines have native roundtrip tests and opt-in ODA import/export coverage for AC1015/AC1018/AC1027; fitted polylines and mesh writing remain unsupported
• ARC angles in raw API are radians (high‑level API converts to degrees)