feat: Option to find missing glyphs in other font files when generating PDFs

[philCryoport]

Is your feature request related to a problem? Please describe. I just found out that there is a plantuml-pdf jar in the release file set. 🙌

Then I saw this at the end of the STDOUT:

Feb 13, 2024 4:07:58 PM org.apache.fop.fonts.Typeface warnMissingGlyph
WARNING: Glyph 9757 (0x261d, pointingindexupwhite) not available in font Helvetica
Feb 13, 2024 4:07:58 PM org.apache.fop.fonts.Typeface warnMissingGlyph
WARNING: Glyph 65039 (0xfe0f, ) not available in font Helvetica

The first one is ☝

The second one is the "Variation Selector-16" -- apparently an "Emoji-specific variation selector" (not exactly how that ended up in my PlantUML...)

Describe the solution you'd like It would be great instead if the PDF generation feature in PlantUML would offer an option where PlantUML would search other fonts on the computer to see if any of those have the missing glyph -- and only if it cannot find it, THEN it reports that it cannot find the glyph.

Alternatively, offer options to:

• List detected fonts
• Make a list of fallback fonts for PlantUML to use

Describe alternatives you've considered 🤷‍♂️

Additional context

• Mentioned in Discord

• In MacOS & Linux, one can use the fc-list command to find which font files have a particular glyph.

  • Example for that "Variation Selector-16" character:

➜ fc-list :charset=fe0f
/System/Library/Fonts/Apple Color Emoji.ttc: .Apple Color Emoji UI:style=Regular
/System/Library/Fonts/LastResort.otf: .LastResort:style=Regular
/System/Library/Fonts/Apple Color Emoji.ttc: Apple Color Emoji:style=Regular,標準體,Ordinær,Normal,Normaali,Regolare,レギュラー,일반체,Regulier,Обычный,常规体,عادي