RE: [Devel] Getting accurate advances

[Turner David]

Hello,

> Turner David wrote:
> > 
> > Why didn't you use the FT_LOAD_LINEAR_DESIGN loading flag ? This
> > would give you the original, untouched, advance in font units.
> > This would let you compute exact advances with the help of
> > face->units_per_EM ?
> > 
> > Hope this helps,
> 
> It definitely does, Thanks. I wasn't aware of FT_LOAD_LINEAR_DESIGN.
> 
> But the documentation is still misleading; if 
> FT_LOAD_LINEAR_DESIGN is 
> not used, linearHoriAdvance is not accurate to 1/65536th of a pixel. 
> What are your thoughts on Werner's and my ideas about changing the 
> calculation of x_scale and linearHoriAdvance to fix this?
> 
Well, the API reference says that it is "expressed" in 16.16 format,
not that the accuracy is extreme.

Changing the way x_scale is computed is interesting, but I believe
that I already tried this, and found that it did distort native TrueType
hinting in certain cases.

However, many things have changed in the engine since. It may be possible
that things are slightly different now. Could someone test this and perform
some important tests with the TrueType bytecode interpreter ?

Regards,

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


> David %^>
> 

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