URL:
<https://savannah.gnu.org/bugs/?59782>
Summary: dwgbmp doesn't work in newer DWG version
Project: LibreDWG
Submitted by: mrclnz
Submitted on: Wed 30 Dec 2020 10:55:24 AM UTC
Category: None
Severity: 3 - Normal
Item Group: None
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
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Details:
More than a bug report this could be a contribution. I did a thumbnail
provider for dwg files, somewhat inspired by dwgbmp.
dwgbmp doesn't work on many post R2000 dwg files, for some different reasons:
- Maybe it can't find the preview block
- It only supports type 1 (BMP) DIBs in 256 color paletted mode
- Newer formats actually have type 6 previews (not documented in the reverse
engineered format), which are simply PNG files stored in the preview block.
I solved the first issue simply by looking for the 16-byte signature (not
elegant but it works); the second issue would need interpreting the DIB header
but I've only seen a couple of file around with a different DIB format. The
third issue is simply handled writing the block as-is as a png file.
I use it with ARES Commander (up to R2018 format) and it seems to work fine.
The tool is here: https://github.com/mrclnz/dwgthumb
It's GPL3 so there shouldn't be any problem
Thanks for the very good work.
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