[cairo] GTKCairo development

[Owen Taylor]

On Tue, 2004-05-04 at 16:26, Bill Spitzak wrote:

> I think a *killer* feature (one that will make Cairo instantly preferrable to 
> every other graphics interface) would be to hide "font sets" inside it. My 
> proposal is simple: when you select a font you are guaranteed that you will 
> get 2^32 possible glyphs, and that you will get equivalent Unicode coverage 
> no matter what font you choose. This will remove the need for Pango to switch 
> fonts, for it to figure out what glyphs exist, and eliminate any need for any 
> interface to indicate what glyphs exist, thus simplifying both Pango and 
> Cairo. More importantly it will mean there will be reasonable compatability 
> between programs using Pango and programs using something else, the glyphs 
> will at least match, even if the positioning is wrong.

Have you thought about:

 Metrics: What do you report for the metrics for this "combined font".
  Is it always going to have a huge descent because it contains 
  Arabic somewhere in there?

 Language tagging: when creating fontsets you want to prefer the fonts
  that have all the characters of the language of the text.

 OpenType and other layout tables: Fonts aren't just collections of 
  glyphs, they also have other tables that determine how these
  fonts interact. (Ligatures, substitutions, etc.)
 
 Integration with native font systems: On Windows, Pango works on top
  of Uniscribe. Uniscribe needs the individual fonts.

 Combining accents: If I have LATIN SMALL LETTER A followed by 
   COMBINING ACUTE ACCENT, how do I select the font that doesn't
   have COMBINING ACUTE ACCENT but has LATIN SMALL LETTER A WITH ACUTE

It's a really complex area; there's no way you can isolate Pango from
the fontset selection process and get good results.

Regards,
						Owen

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