Evas font: Added support for font fallback for eet/edje fonts.

This is a long awaited feature that has been requested years ago.
Fontconfig finally added the support needed to make it happen, so here
it is.

I added a fontconfig query to look for similar fonts in case we loaded a
font from eet/edje/file(no fontconfig). This now works quite well.

Still missing: if you load a bold/italic/whatever font directly (set the file)
without putting ":weight=bold" you will not get run-time emboldenment if
only non-bold fonts are found.

This unfortunately depends on very recent fontconfig version (#ifed out
when unavailable), so only people with fontconfig >= 2.11 will enjoy
this feature.

src/lib/evas/canvas/evas_font_dir.c

@@ -10,6 +10,7 @@
 
 #ifdef HAVE_FONTCONFIG
 #include <fontconfig/fontconfig.h>
+#include <fontconfig/fcfreetype.h>
 #endif
 
 #include "evas_common_private.h"
@@ -783,6 +784,33 @@ evas_font_load(Evas *eo_evas, Evas_Font_Description *fdesc, const char *source,
              font = _evas_load_fontconfig(font, evas->evas, set, size, wanted_rend);
           }
      }
+   else /* Add a fallback list from fontconfig according to the found font. */
+     {
+#if FC_MAJOR >= 2 && FC_MINOR >= 11
+	FcResult res;
+
+        FT_Face face = evas_common_font_freetype_face_get((RGBA_Font *) font);
+
+        if (face)
+          {
+             p_nm = FcFreeTypeQueryFace(face, (FcChar8 *) "", 0, NULL);
+             FcConfigSubstitute(fc_config, p_nm, FcMatchPattern);
+             FcDefaultSubstitute(p_nm);
+
+             /* do matching */
+             set = FcFontSort(fc_config, p_nm, FcTrue, NULL, &res);
+             if (!set)
+               {
+                  FcPatternDestroy(p_nm);
+                  p_nm = NULL;
+               }
+             else
+               {
+                  font = _evas_load_fontconfig(font, evas->evas, set, size, wanted_rend);
+               }
+          }
+#endif
+     }
 #endif
 
 #ifdef HAVE_FONTCONFIG

src/lib/evas/common/evas_font.h

@@ -21,6 +21,7 @@ EAPI int               evas_common_font_instance_max_descent_get      (RGBA_Font
 EAPI int               evas_common_font_instance_underline_position_get       (RGBA_Font_Int *fi);
 EAPI int               evas_common_font_instance_underline_thickness_get      (RGBA_Font_Int *fi);
 EAPI int               evas_common_font_get_line_advance     (RGBA_Font *fn);
+void *evas_common_font_freetype_face_get(RGBA_Font *font); /* XXX: Not EAPI on purpose. Not ment to be used in modules. */
 
 /* draw */
 typedef Eina_Bool (*Evas_Common_Font_Draw_Cb)(RGBA_Image *dst, RGBA_Draw_Context *dc, int x, int y, Evas_Glyph_Array *glyphs, RGBA_Gfx_Func func, int ext_x, int ext_y, int ext_w, int ext_h, int im_w, int im_h);

src/lib/evas/common/evas_font_main.c

@@ -73,6 +73,22 @@ evas_common_font_font_all_unload(void)
    evas_common_font_all_clear();
 }
 
+/* FIXME: This function should not be used. It's a short-cut fix that is meant
+ * to improve font fallback for in-theme fonts. It will break if we stop using
+ * freetype (unlikely) or do anything else fancy. */
+void *
+evas_common_font_freetype_face_get(RGBA_Font *font)
+{
+   RGBA_Font_Int *fi = font->fonts->data;
+
+   if (!fi)
+      return NULL;
+
+   evas_common_font_int_reload(fi);
+
+   return fi->src->ft.face;
+}
+
 EAPI int
 evas_common_font_instance_ascent_get(RGBA_Font_Int *fi)
 {