CoreText backend: implement font fallbacks

We implement font fallbacks by making use of
CTFontCopyDefaultCascadeList, a public, non-exposed, symbol in the
CoreText library.  We might want to handle this differently.

The code now also uses a PangoCoreTextFontsetKey and
PangoCoreTextFontKey, similar to the font config backend. This has also
helped to clean up the code in general.

This patch contains two fixes by Michael Natterer:
 1. Fix a bug in pango_core_text_font_key_equal() where the return value
of memcmp() was wrongly interpreted.
 2. Cache PangoCoverage in PangoCoreTextFont.

1 files changed, 66 insertions, 6 deletions

diff --git a/pango/pangocairo-coretextfontmap.c b/pango/pangocairo-coretextfontmap.c
index e05a1d40..107c8289 100644
--- a/pango/pangocairo-coretextfontmap.c
+++ b/pango/pangocairo-coretextfontmap.c
@@ -44,7 +44,7 @@ pango_cairo_core_text_font_map_set_resolution (PangoCairoFontMap *cfontmap,
 }
 
 static double
-pango_cairo_core_text_font_map_get_resolution (PangoCairoFontMap *cfontmap)
+pango_cairo_core_text_font_map_get_resolution_cairo (PangoCairoFontMap *cfontmap)
 {
   PangoCairoCoreTextFontMap *cafontmap = PANGO_CAIRO_CORE_TEXT_FONT_MAP (cfontmap);
 
@@ -64,7 +64,7 @@ static void
 cairo_font_map_iface_init (PangoCairoFontMapIface *iface)
 {
   iface->set_resolution = pango_cairo_core_text_font_map_set_resolution;
-  iface->get_resolution = pango_cairo_core_text_font_map_get_resolution;
+  iface->get_resolution = pango_cairo_core_text_font_map_get_resolution_cairo;
   iface->get_font_type  = pango_cairo_core_text_font_map_get_font_type;
 }
 
@@ -74,13 +74,11 @@ G_DEFINE_TYPE_WITH_CODE (PangoCairoCoreTextFontMap, pango_cairo_core_text_font_m
 
 static PangoCoreTextFont *
 pango_cairo_core_text_font_map_create_font (PangoCoreTextFontMap       *fontmap,
-                                            PangoContext               *context,
-                                            PangoCoreTextFace          *face,
-                                            const PangoFontDescription *desc)
+                                            PangoCoreTextFontKey       *key)
 
 {
   return _pango_cairo_core_text_font_new (PANGO_CAIRO_CORE_TEXT_FONT_MAP (fontmap),
-                                          context, face, desc);
+                                          key);
 }
 
 static void
@@ -89,6 +87,62 @@ pango_cairo_core_text_font_map_finalize (GObject *object)
   G_OBJECT_CLASS (pango_cairo_core_text_font_map_parent_class)->finalize (object);
 }
 
+static double
+pango_cairo_core_text_font_map_get_resolution_core_text (PangoCoreTextFontMap *ctfontmap,
+                                                         PangoContext         *context)
+{
+  PangoCairoCoreTextFontMap *cafontmap = PANGO_CAIRO_CORE_TEXT_FONT_MAP (ctfontmap);
+  double dpi;
+
+  if (context)
+    {
+      dpi = pango_cairo_context_get_resolution (context);
+
+      if (dpi <= 0)
+        dpi = cafontmap->dpi;
+    }
+  else
+    dpi = cafontmap->dpi;
+
+  return dpi;
+}
+
+static gconstpointer
+pango_cairo_core_text_font_map_context_key_get (PangoCoreTextFontMap *fontmap G_GNUC_UNUSED,
+                                                PangoContext         *context)
+{
+  return _pango_cairo_context_get_merged_font_options (context);
+}
+
+static gpointer
+pango_cairo_core_text_font_map_context_key_copy (PangoCoreTextFontMap *fontmap G_GNUC_UNUSED,
+                                                 gconstpointer         key)
+{
+  return cairo_font_options_copy (key);
+}
+
+static void
+pango_cairo_core_text_font_map_context_key_free (PangoCoreTextFontMap *fontmap G_GNUC_UNUSED,
+                                                 gpointer              key)
+{
+  cairo_font_options_destroy (key);
+}
+
+static guint32
+pango_cairo_core_text_font_map_context_key_hash (PangoCoreTextFontMap *fontmap G_GNUC_UNUSED,
+                                                 gconstpointer         key)
+{
+  return (guint32)cairo_font_options_hash (key);
+}
+
+static gboolean
+pango_cairo_core_text_font_map_context_key_equal (PangoCoreTextFontMap *fontmap G_GNUC_UNUSED,
+                                                  gconstpointer         key_a,
+                                                  gconstpointer         key_b)
+{
+  return cairo_font_options_equal (key_a, key_b);
+}
+
 static void
 pango_cairo_core_text_font_map_class_init (PangoCairoCoreTextFontMapClass *class)
 {
@@ -97,7 +151,13 @@ pango_cairo_core_text_font_map_class_init (PangoCairoCoreTextFontMapClass *class
 
   object_class->finalize = pango_cairo_core_text_font_map_finalize;
 
+  ctfontmapclass->get_resolution = pango_cairo_core_text_font_map_get_resolution_core_text;
   ctfontmapclass->create_font = pango_cairo_core_text_font_map_create_font;
+  ctfontmapclass->context_key_get = pango_cairo_core_text_font_map_context_key_get;
+  ctfontmapclass->context_key_copy = pango_cairo_core_text_font_map_context_key_copy;
+  ctfontmapclass->context_key_free = pango_cairo_core_text_font_map_context_key_free;
+  ctfontmapclass->context_key_hash = pango_cairo_core_text_font_map_context_key_hash;
+  ctfontmapclass->context_key_equal = pango_cairo_core_text_font_map_context_key_equal;
 }
 
 static void