Thank you for your excellent reply! I modified the code per your
suggestions and it worked perfectly. Here is the full snippet of code for
anyone else who might find this useful:
cairo_font_options_t *options;
cairo_t *cr;
PangoFontMap *fm;
PangoContext *context;
PangoLayout *layout;
PangoFontDescription *pfd;
cr = gdk_cairo_create (pixmap);
fm = pango_cairo_font_map_get_default ();
pango_cairo_font_map_set_resolution (PANGO_CAIRO_FONT_MAP(fm), 96);
context = pango_cairo_font_map_create_context
(PANGO_CAIRO_FONT_MAP(fm));
options = cairo_font_options_create ();
cairo_font_options_set_hint_style (options, CAIRO_HINT_STYLE_NONE);
cairo_font_options_set_hint_metrics (options, CAIRO_HINT_METRICS_OFF);
pango_cairo_context_set_font_options (context, options);
layout = pango_layout_new (context);
pango_layout_set_text (layout,text_string,-1);
pfd = pango_font_description_new ();
pango_font_description_set_size (pfd,12*PANGO_SCALE*scale_factor);
pango_layout_set_font_description (layout,pfd);
cairo_move_to (cr, x, y);
pango_cairo_show_layout (cr,layout);
So, I guess I ended up using some default font which I presume is not a
freetype font. But, it worked. To answer your question below, I did check
for NULL and indeed the font map created was NULL.... which means as you
indicate that the cairo I have is not compiled with the freetype backend
enabled. For what it's worth, I also tried it with the "TOY" font and I got
the same error.
I am running on mingw windows with the binaries derived straight from Tor's
page.
Thanks again for your help,
Karl
> -----Original Message-----
> From: Behdad Esfahbod [mailto:[EMAIL PROTECTED] On Behalf Of
> Behdad Esfahbod
> Sent: Thursday, December 06, 2007 2127 PM
> To: Karl Reis
> Cc: gtk-app-devel-list@gnome.org
> Subject: Re: Linear Scaling of fonts with FreeType on Cairo
>
> On Thu, 2007-12-06 at 19:01 -0800, Karl Reis wrote:
> > I'm trying to find a way to scale fonts linearly. As far as I can tell,
> the
> > way to do it is to use a freetype font and turn hinting off. Using the
> API,
> > I tried to pull some code together that would try to do that, but
> > unfortunately, the font is still scaling non-linearly.
>
> You're on the right track. All font backends are supposed to support
> that but I'm not sure how non-freetype ones handle it right now.
>
>
> > cairo_font_options_t *options;
> >
> > PangoFontMap *fm;
> >
> > PangoContext *context;
> >
> >
> >
> > fm = pango_cairo_font_map_new_for_font_type (CAIRO_FONT_TYPE_FT);
> >
> > pango_cairo_font_map_set_resolution (PANGO_CAIRO_FONT_MAP(fm), 96);
> >
> > context = pango_cairo_font_map_create_context
> > (PANGO_CAIRO_FONT_MAP(fm));
> >
> >
> >
> > options = cairo_font_options_create ();
> >
> > cairo_font_options_set_hint_style (options, CAIRO_HINT_STYLE_NONE);
> >
> > pango_cairo_context_set_font_options (context, options);
> >
> > During runtime I receive the following error:
> >
> > Pango-CRITICAL **: pango_cairo_font_map_create_context: assertion
> > `PANGO_IS_CAIRO_FONT_MAP (fontmap)' failed
>
> What's your platform? This pretty much means that
> pango_cairo_font_map_new_for_font_type() returned NULL, which according
> to the docs, means that pango detected at compile time that your cairo
> isn't compiled with the freetype font backend enabled.
>
> Most of the time you just need pango_cairo_font_map_get_default().
>
>
> > Specifically, how can I use a PangoCairoFontMap in such a scenario? The
> > documentation states that I should be getting such a structure upon
> calling
> > pango_cairo_font_map_new_for_font_type. However, all I get is a
> > PangoFontMap. I'm not sure what the difference is between these two
> > structures and/or if one can be type cast onto another.
>
> PangoCairoFontMap is a PangoFontMap. Think object-oriented programming.
>
>
> > More generally, how can I scale fonts linearly using the Pango, Cairo
> API?
>
> You are setting hint_style. That affects rendering of the glyphs but
> not their extents. You should turn metrics hinting off for that.
> cairo_font_options_set_hint_metrics().
>
>
> > Tutorials, guides would be very helpful.
>
> A tutorial is in the works right now, but far from complete:
>
> http://bugzilla.gnome.org/show_bug.cgi?id=502222
>
> > Thanks,
> >
> >
> >
> > Karl
>
>
> Have fun with pangocairo!
>
> --
> behdad
> http://behdad.org/
>
> ...very few phenomena can pull someone out of Deep Hack Mode, with two
> noted exceptions: being struck by lightning, or worse, your *computer*
> being struck by lightning. -- Matt Welsh
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