Re: [Devel] [OpenType] Hinting question

[David Turner]

Hello James,

"James H. Cloos Jr." a écrit :
> 
> The attached message was sent to the opentype list.
> 
> It implies that ttf (glyf) fonts can be the logical equivalent of
> optical axis multiple master fonts given that point size, device
> resolution and font transform are separate args to the bci.  As such,
> if the point size arg is used to carry the design size and the
> transform is used to modify that into the user's request size, the
> logical equivalent of optical scaling should result.
> 
> Provided that the font designer and the rasterization engine coöperate.
> 
> Are there any implementation details in freetype of xft{1,2} that
> would prevent this from working?
>
Actually, this can work with FreeType (1 and 2) since it follows the
TrueType specification that specifically differentiate the point size
from the pixel size during bytecode generation..

However, the resolution is only recorded when calling FT_Set_Char_Size
in FT2, and not FT_Set_Pixel_Sizes. So, if an application doesn't use
the former function, optical scaling will not be possible..

That's also the reason why each font driver has two distinct entries
to reset the character size in its "size" class implementation.


Hope this helps,

- David Turner
- The FreeType Project  (www.freetype.org)