Automate dxf file with Python & ezdxf

Overview

• ezdxf is
  • open source so you can use it for free
  • no dependency on AutoCAD, so you can use it on any computer
  • no dependency on windows so you can use it on any operating system or web apps like streamlit
  • In Active development with really good documentation
  • Documentation
• Requirements
  • python 3.9 or higher

Setup

• use Pip install ezdxf to install xlwings package

Write new dxf file

Create new dxf file

• Copy the code below and run it to generate dxf file with circle
• we are using (0,0) for point inputs

import ezdxf

# create a new DXF
doc = ezdxf.new()

# get model space
msp = doc.modelspace()

# add circle to model space
circle = msp.add_circle((0, 0), 10)

# save the DXF document
doc.saveas("output.dxf")

Make sure that output.dxf file is not open while running this script. We won’t be able to write dxf file while it is open.

Document

• you can pass specific dxf version with new function

doc = ezdxf.new()
doc = ezdxf.new(dxfversion="R2010")
doc = ezdxf.new(dxfversion="R2013")

• By Default, dxf file is save in current directory
• you can also save it in specific location by passing path

doc.saveas("Output.dxf")
doc.saveas(r"C:\Users\Ryzen2600x\Downloads\Output.dxf")

Layer

• make sure to add layer before you start adding new entities to dxf file
• you can also pass LineType, LineWeight and Transparancy to add method
• use can use dxfattribs parameter to assign layer to specific entity like shown in circle example below

# Create a new layer with color 1 (red)
doc.layers.add("REINFOCEMENT", color=ezdxf.colors.RED)

LineType

• Predefine Line Type
• add linetypes Import from ezdxf.tools.standards import linetypes

# define paramters for linetype
lineTypeName = "CENTERLINE"
lineTypePatternName = "CENTER"
lineTypeDiscription = ""
lineTypePattern = ""

# Loop through lineTypesList to find the linetype with DASHDOT value as the first item
for linetype in linetypes():
    if linetype[0] == lineTypePatternName:
        lineTypeDiscription = linetype[1]
        lineTypePattern = linetype[2]
        break

if lineTypeName not in doc.linetypes:
    doc.linetypes.add(lineTypeName, lineTypePattern,
                      description=lineTypeDiscription)

• For Custom Line Type, you have to manually define pattern, as shown below
  • here 2 pattern length
  • 1.25 and -0.25 is for first dash
  • 1.25 and -0.25 is for second dash

if "CENTERLINE" not in doc.linetypes:
    doc.linetypes.add(name='CENTERLINE', pattern=[
                      2.0, 1.25, -0.25, 1.25, -0.25])

Transparency

• you can set transparency of entity between 0 and 1
• 0 means fully opaque
• 1 means fully transparent

# Draw circle in 0 layer
circle = msp.add_circle((0, 0), 10)
circle.transparency = 0.5

Entity dxf attributes

# Draw circle with red color
circle = msp.add_circle((0, 0), 100, dxfattribs={"color": color=ezdxf.colors.RED})

# Draw circle with specific layer
circle = msp.add_circle((0, 0), 100, dxfattribs={"layer": "REINFOCEMENT"})
circle = msp.add_circle((0, 0), 100, dxfattribs={"layer": "REINFOCEMENT", "color": color=ezdxf.colors.YELLOW})

Sample codes

Circle

# Draw circle in 0 layer
circle = msp.add_circle((0, 0), 10)

Line

line = msp.add_line((0, 0), (100, 100))

Polyline

points = [(0.0, 0.0)]
points.append((100, 0))
points.append((100, 100))
points.append((0, 100))

msp.add_lwpolyline(points)

Text

text = msp.add_text("Hello,World.", height=50, rotation=45)
text.set_placement((100, 100), align=ezdxf.enums.TextEntityAlignment.CENTER)

MText

mtext = msp.add_mtext("Hello,World.")
mtext.set_location((100, 100), rotation=45)

Arc

arc = msp.add_arc(center=(0, 0), radius=100, start_angle=0, end_angle=90)

Ellipse

ellipse = msp.add_ellipse(center=(0, 0), major_axis=(
    100, 0), ratio=0.5)

ellipse = msp.add_ellipse(center=(0, 0), major_axis=(
    100, 0), ratio=0.5, start_param=math.pi/2, end_param=math.pi)

Linear Dimension

msp.add_line((0, 0), (10, 10))
dim = msp.add_linear_dim(
    base=(5, 15),  # location of the dimension text
    p1=(0, 0),  # Start point
    p2=(10, 10),  # End point
    dimstyle="Standard",
    text="L=<>",
)
dim.render()# Don't Skip this

Aligned Dimension

msp.add_line((0, 0), (10, 10))
dim = msp.add_aligned_dim(
    p1=(0, 0),  # Start point
    p2=(10, 10),  # End point
    distance=2,
    dimstyle="Standard",
    text="L=<>",
)
dim.render()  # Don't Skip this

Angular Dimension

dim = msp.add_angular_dim_cra(
    center=(5, 5),  # center point of the angle
    radius=7,  # distance from center point to the start of the extension lines
    start_angle=60,  # start angle in degrees
    end_angle=120,  # end angle in degrees
    distance=3,  # distance from start of the extension lines to the dimension line
    dimstyle="Standard",  # default angular dimension style
)
dim.render()  # Don't Skip this

arc = msp.add_arc(
    center=(0, 0),
    radius=5,
    start_angle=60,
    end_angle=120,
)
dim = msp.add_angular_dim_arc(
    arc.construction_tool(),
    distance=2,
)
dim.render()  # Don't Skip this

Leader

leader = msp.add_leader(
    vertices=[(0, 0), (10, 10), (20, 10)],
    dimstyle="Standard"
)

MultiLeader

ml_builder = msp.add_multileader_mtext("Standard")
ml_builder.quick_leader(
    f"angle={45}°\n2nd text line",# Content
    target=Vec2(0, 0),# Start Point
    segment1=Vec2(20, 20), # End Point Relative to Start
)

Hatch

hatch = msp.add_hatch(color=ezdxf.colors.RED)
hatch.set_pattern_fill("ANSI31", scale=0.5)
hatch.paths.add_polyline_path(
    [(0, 0), (100, 0), (100, 100), (0, 100)], is_closed=True
)

Conclusion

• ezdxf is a great package due to
  • Good documentation
  • Active Development
  • No dependency on AutoCAD
• If you don’t need any interactive with AutoCAD, this is great package to use