Add a test for bitmap font metrics to ensure that they match the Windows ones

[Dmitry Timoshkov]

"Huw Davies" <huw at codeweavers.com> wrote:

>> Looks like it's a sfnt2fnt bug and not a fontforge or FreeType problem.
>> 
>> This patch tests bitmap font metrics to ensure that they match the Windows
>> ones. The patch discovers a bug in sfnt2fnt which causes Courier font to
>> have wrong ascent and descent values (13/0 instead of 11/2). courier.ttf
>> generated by fontforge from courier.sfd has correct values, but courier-*.fnt
>> files have wrong values.
> 
> Well we get the ascent from the height of the Aring glyph.  As far as
> I can tell this is 11 in fontforge.  So somewhere between fontforge's
> export as a ttf and sfnt2fnt reading that ttf (using FreeType) the
> value has changed to 13.  Hence my comment that either fontforge or
> FreeType is doing something odd.

I was going to point out that I tried to replace in tools/sfnt2fnt.c

ascent = face->glyph->metrics.height >> 6;

by

ascent = face->size->metrics.ascender >> 6;

which is what is used in dlls/gdi/freetype.c,get_bitmap_text_metrics(),
but that breaks MS Sans Serif bitmap fonts. It looks like fontforge
doesn't allow to have a different font header for each different bitmap
size in the bitmap font.

-- 
Dmitry.