non win-1252 characters in SVG

[nbkolchin]

Asciidoctor input:

[blockdiag, format="svg"]
.Пример диаграммы
----
blockdiag {
  A[label="изображение"];
  B[label="color filtering"];
  A -> B;
}
----

Theme file:

font:
  catalog:
    PTAstraSerif:
      normal: PTAstraSerif-Regular.ttf
      bold: PTAstraSerif-Bold.ttf
      italic: PTAstraSerif-Italic.ttf
      bold_italic: PTAstraSerif-BoldItalic.ttf
  fallbacks:
    - PTAstraSerif
base:
  font_family: PTAstraSerif

Generated svg:

...
  <text fill="rgb(0,0,0)" font-family="sans-serif" font-size="11" font-style="normal" font-weight="normal" text-anchor="middle" textLength="64" x="320" y="67">color filtering</text>
...

Asciidoctor execution:

$ asciidoctor-pdf \
    -a pdf-style=$HOME/.asciidoctor/themes/basic-theme.yml \
    -a pdf-fontsdir=$HOME/.asciidoctor/fonts \
    -r asciidoctor-diagram \
    test.adoc
The following text could not be fully converted to the Windows-1252 character set:
| изображение

There is no way to specify SVG font for 'blockdiag', it will always use "sans-serif".

Afaik, there is no way to replace default "sans-serif" in asciidoctor.

If I manually edit generated svg and change "sans-serif" with "PTAstraSerif", everything work without errors.

[mojavelinux]

I'd argue this bug lies with Prawn SVG. Asciidoctor does allow you to map generic font names like sans-serif in your font catalog.

font:
  catalog:
    sans-serif:
      normal: PTAstraSerif-Regular.ttf
      bold: PTAstraSerif-Bold.ttf
      italic: PTAstraSerif-Italic.ttf
      bold_italic: PTAstraSerif-BoldItalic.ttf

However, Prawn SVG is not respecting these mappings. If it sees a generic font name (e.g., sans-serif), it maps it to a built-in AFM font (e.g., Helvetica) without first consulting the font registry. You can see where this happens here:

https://github.com/mogest/prawn-svg/blob/5d40c5fab3eabc34650269c663931f98c3b4430e/lib/prawn/svg/font.rb#L24

If Prawn SVG where to consult the font registry first, everything would work.

There is a workaround for this problem. Create a file named prawn-svg-patch.rb with the following content:

require 'prawn-svg'

Prawn::SVG::Font::GENERIC_CSS_FONT_MAPPING['sans-serif'] = 'PTAstraSerif'

Then load it when you are calling Asciidoctor PDF:

$ asciidoctor-pdf -r ./prawn-svg-patch.rb -r asciidoctor-diagram diagram.adoc

Would you be willing to file the bug/feature request in Prawn SVG?

[mojavelinux]

I also spent time trying to figure out how to get blockdiag to use a font other than sans-serif. Even though I was able to configure a custom fontmap and define new fonts, I could never figure out where it decides to use sans-serif in the SVG. It almost appears as though the font configuration is for raster output only. blockdiag is extremely limited in this regard and the documentation lacking. That's too bad. If there was a clear way to set the font in blockdiag, I'm sure we could add it to Asciidoctor Diagram.

[mojavelinux]

See mogest/prawn-svg#93.

[mojavelinux]

PR sent.

[nbkolchin]

Thank you for workaround. I'm not familiar enough with Prawn to file bugreport.

I reported font selection problem to blockdiag upstream.

https://bitbucket.org/blockdiag/blockdiag/issues/82/add-ability-to-change-font-family-for-svg

But, they think that this can be achieved with 'fontmap' and don't explain how.

P.S. Sorry, for delay in replying.

[mojavelinux]

Thank you for workaround. I'm not familiar enough with Prawn to file bugreport.

I've already filed a report and submitted a patch. See mogest/prawn-svg#94

they think that this can be achieved with 'fontmap' and don't explain how.

Perhaps I'm just too stupid, but I could not figure out how to use fontmap. The configuration is extremely obtuse. But we already have the mapping we need if we can just get prawn-svg to respect it.

[mojavelinux]

This is now resolved upstream. You'll be able to take advantage of it in alpha.16.

[nbkolchin]

Great. Thank you.