Re: A couple of issues with freetype2-beta6

[David Turner]

Hi Elliot,

> 
> . The ft_render_grays renderer doesn't seem to render to the full range of
> grays available to it - the darkest I can get is a sorry gray, even in the
> spots that should be black. (I'm aware of the bit depth being produced - I
> changed the PIXEL_BITS define to 8 and still no joy.)
> 
It's not a question of bit-depth :-) The number of grays used in the
renderer as been changed from 128 (in beta 6 and before) to 256 (in beta7),
so I'ds suggest you to download the latest version..

Note that if you precisely want to control the gray levels (their number,
add gamma correction, perform compositing, etc..), you'll need to provide
your own span rendering callback to the renderer and perform all
computations yourself. Wait for beta-8 for more documentation on this,
or try to read the source (see FT_Raster_Funcs in <freetype/ftimage.h>
for example).

As you probably know, FreeType is not a graphics library, so there are
a number of things it will never do, even if you ask it for long :-)

> . When loading Type1 fonts, the FT_Size_Metrics structure inside the
> FT_Face does not get accurate info set:
> 
> (gdb) p ftf->size->metrics
> $6 = {x_ppem = 12, y_ppem = 12, x_scale = 50331, y_scale = 50331,
>   ascender = 0, descender = 0, height = 0, max_advance = 0}
> 
> ascender, descender, and height are all zero - pretty surely a bug. (This
> example is from loading the Bitstream Charter font.)
> 
Well, this is fixed in beta 7 too :-)

> . In order to go from "slow as molasses" to "bearable speed", it would be
> nice if I could specify my own GlyphSlot to LoadGlyph into so I could
> cache glyphs. This could be facilitated by adding a LoadGlyphSlot routine
> and adding a GlyphSlot member that stored which glyph was last loaded into
> the slot.
> 
Glyph caching is application specific. We'll probably provide a standard
glyph cache later , but it will be considered as an add-on, not part of
the library. As said before, the role of the engine is to access font
data, and eventually help render individual glyphs.

It doesn't do caching, text layout, etc..

Best Regards,

- David

> -- Elliot
> The best way to accelerate a Macintosh is at 9.8 meters per second per second.