Windows: Unloaded Fonts with SVG

[CRTejaswi]

Using mmdc to generate SVG to stdout & file, and, display it using chafa (v1.18.2 on PowerShell v7.6).
Sample .mmd files for validating can be found here.
mmdc infers SVG by default, use -e "svg" explicitly if desired.

ISSUE:
A badly processed image is displayed; more importantly, existing fonts aren't loaded.

mmdc -i _.mmd -o - -t dark -b transparent | chafa --size=70x -f sixel -        # PS7.6 ❌
mmdc -i _.mmd -o _.svg -t dark -b transparent; chafa --size=70x -f sixel _.svg # PS7.6 ❌

(Chafa.exe:1232): librsvg-WARNING **: 20:25:40.607: CSS parsing error
(Chafa.exe:1232): librsvg-WARNING **: 20:25:40.608: CSS parsing error
(Chafa.exe:1232): librsvg-WARNING **: 20:25:40.608: CSS unrecoverable error
parsing error: 1:7859:could not recognize next production
parsing error: 1:7874:while parsing rulset: current char must be a '}'
parsing error: 1:7873:while parsing declaration: next property is malformed
(Chafa.exe:1232): Pango-WARNING **: 20:25:41.115:
couldn't load font ""trebuchet ms", verdana, arial, sans-serif Not-Rotated 7.6796875"
falling back to "Sans Not-Rotated 7.6796875", expect ugly output.

The same issue doesn't exist with SVGs with little to no text (in general).
Where should I look, in order to debug/resolve this issue?

[hpjansson]

Thanks for reporting this. Can you tell me the output from chafa.exe --version?

Are the CSS parsing errors also causing issues, or is it just the font?

[CRTejaswi]

v1.18.2. The fonts as well as the CSS rendering are affected.

chafa --version

Chafa version 1.18.2
Loaders:  GIF JPEG PNG QOI SVG TIFF WebP XWD
Features: mmx sse4.1 popcnt avx2
Applying: mmx sse4.1 popcnt avx2

[hpjansson]

Thanks. I think you're running into limitations of the older, leaner SVG parser in the bundled librsvg. Mermaid uses embedded CSS/HTML that it can't parse. In order to handle this perfectly we'd need something closer to a real browser engine. Chafa is intentionally kept small and lean, so it's unlikely we'll support this soon (though it may happen later, once I figure out how to cross-compile recent librsvg with the Rust toolchain it requires).

The best workaround right now is to give Chafa a PNG file as input. Something like this should work:

mmdc -i _.mmd -o - -e png -t dark -b transparent -s 3 | chafa --size=70x -f sixel -

You can increase the -s scale factor in order to get a big enough PNG for crisp output.

[CRTejaswi]

Thanks for the detailed insight! I'll take a look into this & report back if I can be of help.
You may close this if desired.

[hpjansson]

Great. Please test and let me know if the workaround is adequate for your use. I'll keep this open to remind me to revisit SVG compatibility later on.

[CRTejaswi]

It fails (similar response on WSL). Writing to a file seems to be the only way to make it work for now (with mmdc).

mmdc -i _.mmd -o - -e png -t dark -b transparent -s 3 | chafa --size=70x -f sixel - # PS7.6 ❌
... Chafa.exe: Failed to open '-': Unknown file format
mmdc -i _.mmd -o _.png -t dark -b transparent; chafa --size=70x _.png               # PS7.6 ✔

[hpjansson]

Issues with pipes on Windows is expected (though it should work if you've got the latest everything and there are no encoding shenanigans tripping it up). But why it'd fail on WSL is a mystery. That's plain old Linux, right?

[hpjansson]

Hmmm. How did you obtain mmdc? If it's a Cygwin binary, it could cause the issue you're seeing.

Are you able to make it work in Windows Terminal?

[CRTejaswi]

I installed it via npm. It works well with PS5/PS7 as well as WSL.
The previous WSL issue is possibly due to conflict between internal variables of the individual Windows/WSL node installations. It works correctly with a single WSL nodejs setup, yet, fails when I have a Windows one as well.