Frequently Asked Questions¶

Installation & Setup¶

Q: I get "Cannot find AutoCAD.Application"¶

A: This means AutoCAD is not installed. Make sure to: 1. Install AutoCAD from Autodesk 2. Run AutoCAD at least once to complete registration 3. Ensure you're on Windows (COM support required)

Q: Do I need a specific Python version?¶

A: Python 3.8 or later is recommended. Earlier versions may work but aren't officially supported.

Q: Can I use this on macOS or Linux?¶

A: Unfortunately, no. This library uses Windows COM (Component Object Model) which is Windows-only. You'll need Windows with AutoCAD installed.

Basic Usage¶

Q: Does AutoCAD need to be running?¶

A: Yes, AutoCAD must be running before you initialize the library:

from AutoCAD import AutoCAD

cad = AutoCAD()  # AutoCAD must be running

Q: How do I work with multiple drawings?¶

A: The library connects to the active document:

cad = AutoCAD()
document = cad.doc  # Active document

Switch to a different document in AutoCAD's UI, then the next operation will use that document.

Q: Can I create drawings from scratch?¶

A: Yes, but you need to create a new document in AutoCAD first:

# Create new drawing in AutoCAD using File > New
# Then access it via Python:
cad = AutoCAD()
cad.add_circle(APoint(0, 0, 0), 5)

Objects & Layers¶

Q: What's the difference between add_circle and add_line?¶

A: They create different geometric objects:

circle = cad.add_circle(center, radius)  # Circular object
line = cad.add_line(start, end)          # Linear object

Q: How do I change an object's properties?¶

A: Use the modify methods:

cad.set_object_color(circle, Color.RED)
cad.set_object_layer(circle, "MyLayer")
cad.modify_object_property(circle, "Radius", 10)

Q: Can I delete objects?¶

A: Yes:

cad.delete_object(circle)

Drawing Properties¶

Q: What's the difference between custom and general properties?¶

A: - General Properties: Title, Subject, Author (built-in) - Custom Properties: User-defined properties you create

# General (predefined)
cad.properties.set_title("My Drawing")

# Custom (you define)
cad.properties.add_custom_property("ProjectID", "PROJ-001")

Q: How do I get the number of custom properties?¶

A: Use get_num_custom_info() (Python equivalent of VBA NumCustomInfo):

count = cad.properties.get_num_custom_info()
print(f"Custom properties: {count}")

Q: Do I need to save after changing properties?¶

A: Yes, call save():

cad.properties.set_title("New Title")
cad.save()  # Don't forget this!

Coordinates & Points¶

Q: What units does the library use?¶

A: The library uses AutoCAD's drawing units. These depend on your drawing setup and can be millimeters, inches, feet, etc. Use consistent units throughout your script.

Q: What's the difference between 2D and 3D points?¶

A: Both use the same APoint class:

# 2D (Z = 0)
point_2d = APoint(10, 20, 0)

# 3D (Z = some value)
point_3d = APoint(10, 20, 5)

Q: How do I convert a point to a tuple?¶

A: Use to_tuple():

point = APoint(10, 20, 0)
x, y = point.to_tuple()  # (10, 20)

Troubleshooting¶

Q: My script hangs or doesn't respond¶

A: Possible causes:

AutoCAD is busy - Wait for AutoCAD to finish current operation
Need user input - Some operations need user interaction in AutoCAD
Infinite loop - Check your logic

Add delays if needed:

import time

cad.add_circle(APoint(0, 0, 0), 5)
time.sleep(1)  # Wait 1 second
cad.add_circle(APoint(10, 0, 0), 5)

Q: "CADException: Error..." when creating objects¶

A: Check:

AutoCAD is still running - It might have crashed
Valid parameters - Check point coordinates, radius, etc.
Active layer exists - Object layer must exist
Error handling - Wrap in try-except:

from AutoCAD import CADException

try:
    cad.add_circle(APoint(0, 0, 0), -5)  # Invalid
except CADException as e:
    print(f"Error: {e}")

Q: Performance is slow with many objects¶

A: Try:

Batch operations - Group similar operations
Use layers - Organize objects on layers
Purge drawing - Remove unused elements:

cad.purge()

Advanced Questions¶

Q: Can I access raw COM objects?¶

A: Yes, most objects have COM properties:

circle = cad.add_circle(APoint(0, 0, 0), 5)
radius = circle.Radius  # Direct COM access
circle.Color = 1  # Change color directly

Q: How do I iterate through all objects?¶

A: Use iter_objects():

# All objects
for obj in cad.iter_objects():
    print(obj.EntityName)

# Specific type
for circle in cad.iter_objects("AcDbCircle"):
    print(circle.Radius)

Q: Can I work with blocks?¶