What is the Relationship between ezdxf, dxfwrite and dxfgrabber?¶
In 2010 I started my first Python package for creating DXF documents called dxfwrite, this package can’t read DXF files and writes only the DXF R12 (AC1009) version. While dxfwrite works fine, I wanted a more versatile package, that can read and write DXF files and maybe also supports newer DXF formats than DXF R12.
This was the start of the ezdxf package in 2011, but the progress was so slow, that I created a spin off in 2012 called dxfgrabber, which implements only the reading part of ezdxf, which I needed for my work and I wasn’t sure if ezdxf will ever be usable. Luckily in 2014 the first usable version of ezdxf could be released. The ezdxf package has all the features of dxfwrite and dxfgrabber and much more, but with a different API. So ezdxf is not a drop-in replacement for dxfgrabber or dxfwrite.
Since ezdxf can do all the things that dxfwrite and dxfgrabber can do, I focused on the development of ezdxf, dxfwrite and dxfgrabber are in maintenance-only mode and will not get any new features, just bugfixes.
There are no advantages of dxfwrite over ezdxf, dxfwrite has a smaller
memory footprint, but the
r12writer add-on does the same job as
dxfwrite without any in-memory structures by writing direct to a stream
or file and there is also no advantage of dxfgrabber over ezdxf for ordinary
DXF files, the smaller memory footprint of dxfgrabber is not noticeable and
for really big files the
iterdxf add-on does a better job.
Imported ezdxf package has no content. (readfile, new)¶
AttributeError: partially initialized module ‘ezdxf’ has no attribute ‘readfile’ (most likely due to a circular import)
Did you name your file/script “ezdxf.py”? This causes problems with circular imports. Renaming your file/script should solve this issue.
AttributeError: module ‘ezdxf’ has no attribute ‘readfile’
This could be a hidden permission error, for more information about this issue read Petr Zemeks article: https://blog.petrzemek.net/2020/11/17/when-you-import-a-python-package-and-it-is-empty/
How to add/edit ACIS based entities like 3DSOLID, REGION or SURFACE?¶
The BODY, 3DSOLID, SURFACE, REGION and so on, are stored as ACIS data embedded in the DXF file. The ACIS data is stored as SAT (text) format in the entity itself for DXF R2000-R2010 and as SAB (binary) format in the ACDSDATA section for DXF R2013+. Ezdxf can read SAT and SAB data, but only write SAT data.
The ACIS data is a proprietary format from Spatial Inc., and there exist no free available documentation or open source libraries to create or edit SAT or SAB data, and also ezdxf provides no functionality for creating or editing ACIS data.
The ACIS support provided by ezdxf is only useful for users which have access to the ACIS SDK from Spatial Inc..
Are OLE/OLE2 entities supported?¶
The Wikipedia definition of OLE: Object Linking & Embedding (OLE) is a proprietary
technology developed by Microsoft that allows embedding and linking to documents
and other objects. For developers, it brought OLE Control Extension (OCX), a
way to develop and use custom user interface elements. On a technical level, an
OLE object is any object that implements the
IOleObject interface, possibly
along with a wide range of other interfaces, depending on the object’s needs.
Therefore ezdxf does not support this entities in any way, this only work on Windows and with the required editing application installed. The binary data stored in the OLE objects cannot be used without the editing application.
In my opinion, using OLE objects in a CAD drawing is a very bad design decision that can and will cause problems opening these files in the future, even in AutoCAD on Windows when the required editing application is no longer available or the underlying technology is no longer supported.
All of this is unacceptable for a data storage format that should be accessed for many years or decades (e.g. construction drawings for buildings or bridges).
Rendering SHX Fonts¶
The SHX font format is not documented nor supported by many libraries/packages like Matplotlib and Qt, therefore only SHX fonts which have corresponding TTF-fonts can be rendered by these backends. See also how-tos about Fonts