Why does Pango on Windows fail to open some fonts?

[pangocoder]

I’m experiencing some strange behaviour with Pango on Windows. Some standard Windows fonts fail to open with Pango while others work. For example, there’s no problem using Bauhaus 93, Calibri or Segoe UI with Pango. When trying to open Brush Script MT, however, I get the following error:

(process:928): Pango-WARNING **: 16:43:17.129: couldn't load font "Brush Script MT 144px", falling b
ack to "Sans 144px", expect ugly output.

The same happens with Algerian:

(process:928): Pango-WARNING **: 16:44:23.103: couldn't load font "Algerian 144px", falling b
ack to "Sans 144px", expect ugly output.

Why do some fonts work while others don’t? Doesn’t make sense to me. I use the Pango build provided by MSYS2 for MINGW64.

[lb90]

Hello @pangocoder! Could you share a link to the fonts?

[pangocoder]

Those are standard Windows fonts. They ship with every Windows 10 system but they are probably copyrighted by Microsoft so I can’t upload them here.

[lb90]

Ah, true!

Actually I can see the fonts in GtkFontDialog. Try running gtk4-demo --run=pickers

Here’s the output from pango-list:

$ pango-list | grep -Ei "brush|algerian"
Brush Script MT 
  Italic:      Brush Script MT Italic
  Bold Italic: Brush Script MT Bold Italic
Algerian 
  Extra-Condensed:              Algerian Extra-Condensed
  Oblique Extra-Condensed:      Algerian Oblique Extra-Condensed
  Bold Extra-Condensed:         Algerian Bold Extra-Condensed
  Bold Oblique Extra-Condensed: Algerian Bold Oblique Extra-Condensed

[pangocoder]

Ah, ok, so I have to use “Brush Script MT Italic” instead of “Brush Script MT” and “Algerian Extra-Condensed” instead of “Algerian”. Then Pango opens the fonts.

Still I find it a bit strange that Pango’s font matching falls back to “Sans” when passing “Brush Script MT”. Wouldn’t it make much more sense to fall back to “Brush Script MT Italic” in that case? The family name surely is Brush Script MT. Also, “Algerian” falls back to “Sans” as well. But I think it would be much more reasonable to fall back to “Algerian Extra-Condensed” then…

[pangocoder]

Those are standard Windows fonts. They ship with every Windows 10 system but they are probably copyrighted by Microsoft so I can’t upload them here.

[dboles]

@pangocoder

Still I find it a bit strange that Pango’s font matching falls back to […]

Assuming this answer still applies, that is not Pango’s fault:

@lyager

Actually the font selection is based on the selected Pango font backend. Mostly used (I think) is Fontconfig.

You fonts are basically always chosen by looking at the fonts Unicode coverage, meaning that Fontconfig tries to choose the font that covers the letters in the text you want to render best.

Not knowing if your problem applies to Fontconfig, I won’t go into to much detail. But if so, have a look at fonts-conf, especially the section on ‘font matching’.

[pangocoder]

Ok, so looks like it’s the Windows font mapper which is a bit pedantic and doesn’t accept “Brush Script MT” but only “Brush Script MT Italic”. When using the FT2 backend, which probably uses fontconfig, “Brush Script MT” works as well.