Re: Gravity Support / pangowin32

[Jeremy Moles <jeremy emperorlinux com>]

On Tue, 2012-03-06 at 09:20 -0500, Behdad Esfahbod wrote:
> On 02/22/2012 05:00 PM, Jeremy Moles wrote:
> > Hello everyone. I am interested in getting gravity support to work in
> > Pango on Windows using the Win32 backend (I haven't tested this using
> > hte Fc/FT backend on Windows).
> > 
> > Does anyone have any experience with this?
> 
> Not really.  I designed the vertical support in Pango, but I have no clue
> about the win32 backend.
> 
> 
> > Does anyone know where I
> > would need to start hacking to add support? I don't mind doing the work,
> > but I truly have no idea where to even start.
> 
> Me neither.  Debug back from where you see the problem?
> 
> 
> > In pangowin32-fontmap.c there is a routine:
> > 
> > 	pango_win32_font_map_load_font
> > 
> > ...and this routine will return a valid PangoFont* UNLESS you have
> > gravity set. For whatever reason, the current implementation doesn't
> > understand how to handle the "Rotated-*" style that is added inside the
> > description when gravity is set.
> 
> Fix this function: pango_win32_face_get_face_name() to also unset gravity.  I
> find that function gross BTW.
> 
> 
> > How does gravity actually work in Pango internally? Do the font files on
> > disk have to provide some extra hints?
> 
> Not really.  The backend needs to load a vertical variant of the font though.
>  IIRC, on Windows, prepending an '@' character to the beginning of the family
> name loads the vertical-metrics variant.  So you may want to try that.  There,
> of course, may be other changes needed.  Just search for gravity around the
> fontconfig backend and see what's going on...

I'm currently using mingw64 on Fedora16 to cross-compile Pango for
Windows. Is there a way to encourage Pango to use a particular
backend?  

I don't mind using Fontconfig/Freetype if I need to; in the end, all
that is happening in our code is something very similar to what Clutter
does (or did): a PangoGlyphString is fed to our rendering callback
function, we use Cairo to rasterize the font into a texture, and
maintain our own caching atlas.

We don't actually ever use Pango to "draw" anything, we just use its
layout and styling engine. I don't know if this simplifies things or
not. :)

At any rate, I'll try the things you mentioned right away...

> > Any help would be appreciated, and thanks beforehand...
> 
> behdad
>