freetype-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Devel] Getting accurate advances


From: David Bevan
Subject: Re: [Devel] Getting accurate advances
Date: Tue, 18 Nov 2003 14:10:28 +0000
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.0.2) Gecko/20030208 Netscape/7.02

Werner,

Thanks for your feedback.

Assuming David T agrees that the changes are benign, then I guess we can go ahead.

As far as pfrdrivr is concerned, the pfr_get_metrics() function doesn't seem to provide the information required to calculate a non-rounded value for x_scale (or could it just return size->metrics.x_scale?).

On the other hand, the only call to this function is from FT_Get_PFR_Metrics(), which as far as I can tell is never used.

Thanks again.

David %^>


Werner LEMBERG wrote:
Do you mean this (y components omitted)?

 FT_Set_Pixel_Sizes( FT_Face  face,
FT_UInt pixel_width, FT_UInt pixel_height )

However, I think your responses explain why I'm unwilling to change
the calculation of x_scale.  I don't know why x_scale is set to
different values in different contexts or what uses are made of it
after it is set.


I've now rechecked the use of x_scale and I think that my last
comments were correct.  David, can you have a look too?


So, I don't know why you think FT_Set_Pixel_Sizes() is correct,


Because `pixel_width' (which is set equal to the ppem value) as a
function argument of FT_Set_Pixel_Sizes() is always an integer,
contrary to FT_Set_Char_Size() which can produce a fractional value
for the pixel width (which is then rounded to an integer ppem value).


or why ttdrivr doesn't need changing,


The TrueType module already contains two distinct sets of metrics; one
for hinting and one without hinting.  The former is rounded to integer
values if the TTF needs that, while the latter is always unrounded.


or why you guess that the pfrdrivr code should be changed (though I
can't actually see how it could be changed).


Because only the native TrueType hinter needs integer values, contrary
to FreeType's autohinter which is used for fonts in PFR format.


    Werner

_______________________________________________
Devel mailing list
address@hidden
http://www.freetype.org/mailman/listinfo/devel



--
 ________________________________________________________
 David Bevan, Emtex Ltd.
 Emtex House, Station Road, Kings Langley, Herts. WD4 8LH England
 Tel:    +44 (0)1923 270882
 E-mail: address@hidden
 Web:    www.emtex.com




reply via email to

[Prev in Thread] Current Thread [Next in Thread]