Re: Values of variables has changed after upgrading library.

[Werner LEMBERG]

> In our product we are in process to upgrade freeType library from
> 2.0.9 to 2.10.0 version and compiled the library in 64Bit.

Why 2.10.0 and not the current one, 2.11.0?

> After loading the font using function FT_New_Memory_Face, the values
> of underline_position is coming different in comparing to newer and
> older versions. Due to this underline position in our output has
> moved a few pixels.
> 
> For example: If we load 'Arial Regular' font, the value of
> underline_position in older version is -217 and in new version it is
> -292.
> 
> Similarly after loading the Glyph the values of variables inside
> metrics are also different.

Version 2.0.9 is ancient, released in 2002.  In version 2.3.8,
computation of the underline position has been fixed, taking care of
the underline thickness.

  
https://gitlab.freedesktop.org/freetype/freetype/-/commit/174b8de3283c921d8bddf48325fe42ba7330a930

In version 2.8, global metrics changed for TTFs.  The corresponding
entry in the CHANGES file contains the following.

    - Global size  metrics values  in the  `FT_Size_Metrics' structure
      can be  different for TrueType  fonts.  Reason is that  in older
      FreeType  versions  the  metrics  were  rounded  differently  to
      integer pixels compared  to all other font  formats, yielding an
      inconsistent behaviour if you used non-native hinting.  Starting
      with this  version, global size  metrics for TrueType  fonts are
      handled the same as other  font formats: `ascender' gets rounded
      up,  `descender'  gets  rounded  down,  `height'  gets  normally
      rounded, and `max_advance' gets normally rounded, too.

      If you need more precise values of (global) ascender, descender,
      height, or  `max_advance', please take the  corresponding values
      from the `FT_Face' structure and scale them manually.


     Werner