[cairo] User font take 2

Behdad Esfahbod behdad at cs.toronto.edu
Mon May 8 12:28:47 PDT 2006

On Mon, 8 May 2006, Kristian Høgsberg wrote:

> So thinking about this, yeah, this might just work.  I was working
> with different assumptions, though; that the API should support on
> demand loading of glyphs (to support fonts with a large number of
> glyphs) and that we would want to do hinting.  However, none of the
> custom document fonts (ps and pdf type3 font, svg fonts) that would
> use this feature support hinting and it's probably a safe assumption
> that none of these font formats will be used for big fonts.  In the
> event that we need to support a new full featured font format, that's
> better done as a full cairo font backend or in freetype anyway.

I think I should ask what the goal of the user font API is.  Is
it yet another toy API?  Is it just to satisfy the needs of the
SVG fonts?

Things that I have in mind as possible usecases for the user font
API are:

  - An extension mechanism for cairo's font API.  Such that you
can bridge arbitrary font rendering systems into cairo without
having to write a font backend.  For this the text_to_glyph API
is needed.  I suggest we keep both text_to_glyph and
ucs4_to_glyph as is in the current scaled_font backend.

  - A unified API that I can hook various pseudo-fonts in Pango
onto.  This includes for example the hexbox drawing font and
similar ones that we have not implemented yet (one for having a
single glyph per Unicode script.)  For this kind of uses, a
callback-based API is required.


"Commandment Three says Do Not Kill, Amendment Two says Blood Will Spill"
	-- Dan Bern, "New American Language"

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