Warnings from Inkscape when build docs for deb install

[rodw-au]

I'll keep adding issues I notice in logs as I build ISO's and review the logs. Ignore if of no concern.
I just find the warnings distriact when looking for my errors (the build.log is close to 50000 lines:)

inkscape -D --export-filename=fig21.png /tmp/linuxcnc-dev/docs/src/zh_CN/gcode/images/comp-path_en.svg

** (inkscape:1929925): WARNING **: 11:33:27.805: Failed to wrap object of type 'PangoFT2FontMap'. Hint: this error is commonly caused by failing to call a library init() function.

** (inkscape:1929925): WARNING **: 11:33:28.941: Failed to wrap object of type 'GtkRecentManager'. Hint: this error is commonly caused by failing to call a library init() function.
inkscape -D --export-filename=fig22.png /tmp/linuxcnc-dev/docs/src/zh_CN/gcode/images/comp02_en.svg

** (inkscape:1929947): WARNING **: 11:33:29.068: Failed to wrap object of type 'PangoFT2FontMap'. Hint: this error is commonly caused by failing to call a library init() function.

** (inkscape:1929947): WARNING **: 11:33:30.218: Failed to wrap object of type 'GtkRecentManager'. Hint: this error is commonly caused by failing to call a library init() function.
inkscape -D --export-filename=fig23.png /tmp/linuxcnc-dev/docs/src/zh_CN/gcode/images/g2_en.svg

** (inkscape:1929968): WARNING **: 11:33:30.370: Failed to wrap object of type 'PangoFT2FontMap'. Hint: this error is commonly caused by failing to call a library init() function.

** (inkscape:1929968): WARNING **: 11:33:31.715: Failed to wrap object of type 'GtkRecentManager'. Hint: this error is commonly caused by failing to call a library init() function.
inkscape -D --export-filename=fig24.png /tmp/linuxcnc-dev/docs/src/zh_CN/gcode/images/g2-3_en.svg

** (inkscape:1929991): WARNING **: 11:33:31.833: Failed to wrap object of type 'PangoFT2FontMap'. Hint: this error is commonly caused by failing to call a library init() function.

** (inkscape:1929991): WARNING **: 11:33:33.117: Failed to wrap object of type 'GtkRecentManager'. Hint: this error is commonly caused by failing to call a library init() function.
inkscape -D --export-filename=fig25.png /tmp/linuxcnc-dev/docs/src/zh_CN/gcode/images/g76-threads_en.svg

** (inkscape:1930014): WARNING **: 11:33:33.263: Failed to wrap object of type 'PangoFT2FontMap'. Hint: this error is commonly caused by failing to call a library init() function.

** (inkscape:1930014): WARNING **: 11:33:34.563: Failed to wrap object of type 'GtkRecentManager'. Hint: this error is commonly caused by failing to call a library init() function.
inkscape -D --export-filename=fig26.png /tmp/linuxcnc-dev/docs/src/zh_CN/gcode/images/eight-holes_en.svg

** (inkscape:1930035): WARNING **: 11:33:34.691: Failed to wrap object of type 'PangoFT2FontMap'. Hint: this error is commonly caused by failing to call a library init() function.

** (inkscape:1930035): WARNING **: 11:33:35.771: Failed to wrap object of type 'GtkRecentManager'. Hint: this error is commonly caused by failing to call a library init() function.
inkscape -D --export-filename=fig27.png /tmp/linuxcnc-dev/docs/src/zh_CN/gcode/images/twelve-holes_en.svg

** (inkscape:1930050): WARNING **: 11:33:35.897: Failed to wrap object of type 'PangoFT2FontMap'. Hint: this error is commonly caused by failing to call a library init() function.

** (inkscape:1930050): WARNING **: 11:33:37.277: Failed to wrap object of type 'GtkRecentManager'. Hint: this error is commonly caused by failing to call a library init() function.
inkscape -D --export-filename=fig28.png /tmp/linuxcnc-dev/docs/src/zh_CN/gcode/images/g81mult_en.svg

** (inkscape:1930066): WARNING **: 11:33:37.425: Failed to wrap object of type 'PangoFT2FontMap'. Hint: this error is commonly caused by failing to call a library init() function.

** (inkscape:1930066): WARNING **: 11:33:38.656: Failed to wrap object of type 'GtkRecentManager'. Hint: this error is commonly caused by failing to call a library init() function.
inkscape -D --export-filename=fig29.png /tmp/linuxcnc-dev/docs/src/zh_CN/gcode/images/g81ex1_en.svg

** (inkscape:1930075): WARNING **: 11:33:38.802: Failed to wrap object of type 'PangoFT2FontMap'. Hint: this error is commonly caused by failing to call a library init() function.

** (inkscape:1930075): WARNING **: 11:33:40.016: Failed to wrap object of type 'GtkRecentManager'. Hint: this error is commonly caused by failing to call a library init() function.
inkscape -D --export-filename=fig30.png /tmp/linuxcnc-dev/docs/src/zh_CN/gcode/images/g81ex2_en.svg

** (inkscape:1930083): WARNING **: 11:33:40.147: Failed to wrap object of type 'PangoFT2FontMap'. Hint: this error is commonly caused by failing to call a library init() function.

** (inkscape:1930083): WARNING **: 11:33:41.413: Failed to wrap object of type 'GtkRecentManager'. Hint: this error is commonly caused by failing to call a library init() function.
inkscape -D --export-filename=fig31.png /tmp/linuxcnc-dev/docs/src/zh_CN/gcode/images/g81_en.svg

** (inkscape:1930092): WARNING **: 11:33:41.564: Failed to wrap object of type 'PangoFT2FontMap'. Hint: this error is commonly caused by failing to call a library init() function.

** (inkscape:1930092): WARNING **: 11:33:42.735: Failed to wrap object of type 'GtkRecentManager'. Hint: this error is commonly caused by failing to call a library init() function.
inkscape -D --export-filename=fig32.png /tmp/linuxcnc-dev/docs/src/zh_CN/gcode/images/g81a_en.svg

** (inkscape:1930099): WARNING **: 11:33:42.864: Failed to wrap object of type 'PangoFT2FontMap'. Hint: this error is commonly caused by failing to call a library init() function.

** (inkscape:1930099): WARNING **: 11:33:43.922: Failed to wrap object of type 'GtkRecentManager'. Hint: this error is commonly caused by failing to call a library init() function.
Image 'gui/images/gremlin_extents_non-rotated_link.png' not found

[BsAtHome]

These are afaik a result of the TeX involvement converting SVG to PDF.
If you know a way to use rsvg-convert, without rewriting the way docs are built, then please let me know.

[grandixximo]

The warnings come from dblatex calling inkscape -D --export-filename=... directly (hardcoded in dbtexmf/core/imagedata.py).

One way to swap in rsvg-convert without touching the docs build: drop a small shim named inkscape in a tools dir and prepend it to PATH for the docs build. It parses the few args dblatex passes and forwards to rsvg-convert -f pdf/png/eps -o OUT IN. dblatex stays unchanged, no Pango/GTK init, warnings gone.

Quick benchmark on 20 SVGs from docs/src/gcode/images/ (Inkscape 1.4 vs librsvg 2.60):

Format	Inkscape	rsvg-convert	Speedup
PNG	5.03s	0.79s	6.4x
PDF	4.70s	0.56s	8.4x

Most of the win is process startup (Inkscape ~150 ms each, rsvg ~5 ms). Across the 124 SVGs in docs/src/, that is roughly 25 s saved per single-language PDF build, ~2 min on a 5-language build. Output sizes comparable, visual quality on these figures looks equivalent.

Caveats: needs librsvg2-bin in build-deps, and a visual diff on a handful of PDFs to confirm rsvg renders all SVGs acceptably (text fonts and filters can differ). Shim can fall back to real inkscape if rsvg-convert is missing.

Worth a try? Happy to put up a PR if you think it is the right direction.

[grandixximo]

Root cause: dblatex hardcodes inkscape -D --export-filename=OUT IN in dbtexmf/core/imagedata.py. The warnings come from headless Inkscape's Pango/GTK init.

Posted #4043 with a small shim: a bash script named inkscape in scripts/ (already on the docs build PATH) that translates the dblatex call into rsvg-convert. dblatex untouched. Falls back to real Inkscape if args do not match the pattern, if rsvg-convert is missing, or if LINUXCNC_DOCS_NO_RSVG=1 is set.

Measured on Master_Documentation: 51.5s -> 46.8s (9% faster), zero pixel diff across all 1055 pages.

[rodw-au]

Yes, I was just thinking about this. I did some research and came to the same conclusion. Good to see the time saving approximated. I wasn't sure if I knew enough about how the docs were built and where to place the shim. In /scripts?

Ooops you've done it!

[grandixximo]

Yeah, will see if works for maintainers, not sure if it's the right way to silence the warnings, it does seem to work...