Can't open DXF and save $INSUNITS, unless file already had $INSUNITS

[velle]

I am very new to DXF, so I probably missed something very basic :)

I am trying to save to DXF from Inkscape, but the units are not included. So I am trying to fix that with ezdxf.

#simple.py
import ezdxf, sys
from ezdxf import units

doc = ezdxf.readfile('frominkscape.dxf')
print('before        $INSUNITS:',doc.header.get('$INSUNITS'))
print('before        doc.units:',doc.units)

doc.units = units.CM # 5 
doc.saveas('outp.dxf')
print('after         $INSUNITS:',doc.header.get('$INSUNITS'))
print('after         doc.units:',doc.units)

outpdoc = ezdxf.readfile('outp.dxf')
print('saved file:   $INSUNITS:',outpdoc.header.get('$INSUNITS')) # None
print('saved file:   doc.units:',outpdoc.units) # throws exception

This will output:

before        $INSUNITS: None
before        doc.units: 0
after         $INSUNITS: 5
after         doc.units: 5
saved file:   $INSUNITS: None
saved file:   doc.units: 0

Why is the header not saved? :)

If I run the same code with a file that already has this header defined with some value, it will be saved with the new value of that header. Also, if I create a new doc with ezdxf.new(), I am able to save this header.

Sample code for frominkscape.dxf: https://gist.github.com/velle/096c7e570d69bcb40eb4aa879fa2159f#file-frominkscape-dxf

Using ezdxf 1.1.4.

[mozman]

Thank you for providing the example file. You can attach DXF files in a zip-archive.

You really missed something but its not documented (not by Autodesk and not in the ezdxf documentation). $INSUNITS require DXF R2000 or later, your DXF file is DXF R12.

[velle]

Thanks :)

Is there any way of getting such feedback from the library? Nothing comes up if I set the $INSUNITS header and run validate(). Should it / could it show there, or is that for something entirely different?

Or are there some warning messages that I can un-suppress, so they will give me such hints?

[mozman]

There are so many quirks and edge cases to document I could just do that for the next years ...

[velle]

Got it. Its obvious that you put much effort in to documenting this library, including documenting DXW. Well done, and thanks :)