[Freetype] Hinting of cached outline glyphs...

[Richard Barber]

Hiya,

I'm currently using a version of Freetype2 (a CVS snapshot
from sometime between 2.0 beta 8 and 2.0 release) with the
first version of the caching subsystem.

Currently we make use of the ft_image_grays bitmap glyph
format for plotting glyphs and the ft_image_outline glyph
type for measuring the size of the glyphs before they're plotted
(nothing particularly unusual there).

However I'm noticing that when caching the outling the cache
_appears_ to only cache the original glyph outline and not
the outline that is generated once the glyph has been scaled
to suit the current font size - therefore at the moment we
are noticing that for every estimation of the size of
a string, followed by actually plotting the string, the
truetype bytecode interpreter is being run twice per glyph!

We've tried applying ft_image_grays to both operations
but with only a small cache size, we tend to find that
the bitmap generated while measuring has been ejected
by the time that we come to plot it - and so we have to
re-render it anyway!

Any suggestions? Is there a good reason why _hinted_ glyph
outlines are not cached, and/or is there any way of getting
the cache to store a ft_image_grays glyph without actually
neccesarily generating the Glyph->buffer?

many thanks,
Richard