[pango/hb-getters] Fixup: Cache the hb_font_t in the fontend

[Matthias Clasen <matthiasc src gnome org>]

commit 29d63dcb49369b55a98b402b9f7e53d336882693
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Nov 19 10:29:03 2018 -0500

    Fixup: Cache the hb_font_t in the fontend
    
    Change the vfunc to be create_hb_font, since
    that is what it does. We keep pango_font_get_hb_font
    as the getter, but make it transfer none and cache
    the hb_font in the frontend.

 pango/fonts.c        | 37 +++++++++++++++++++++++++++++++------
 pango/pango-font.h   |  2 +-
 pango/pangofc-font.c |  6 +++---
 3 files changed, 35 insertions(+), 10 deletions(-)
---
diff --git a/pango/fonts.c b/pango/fonts.c
index 28614b2f..0a06ce3a 100644
--- a/pango/fonts.c
+++ b/pango/fonts.c
@@ -1617,11 +1617,29 @@ pango_parse_stretch (const char   *str,
  * PangoFont
  */
 
-G_DEFINE_ABSTRACT_TYPE (PangoFont, pango_font, G_TYPE_OBJECT)
+typedef struct {
+  hb_font_t *hb_font;
+} PangoFontPrivate;
+
+G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (PangoFont, pango_font, G_TYPE_OBJECT)
+
+static void
+pango_font_finalize (GObject *object)
+{
+  PangoFont *font = PANGO_FONT (object);
+  PangoFontPrivate *priv = pango_font_get_instance_private (font);
+
+  hb_font_destroy (priv->hb_font);
+  
+  G_OBJECT_CLASS (pango_font_parent_class)->finalize (object);
+}
 
 static void
 pango_font_class_init (PangoFontClass *class G_GNUC_UNUSED)
 {
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+
+  object_class->finalize = pango_font_finalize;
 }
 
 static void
@@ -1843,7 +1861,7 @@ pango_font_get_font_map (PangoFont *font)
  *
  * Get a hb_font_t object backing this font.
  *
- * Returns: (transfer full) (nullable): the hb_font_t object backing the
+ * Returns: (transfer none) (nullable): the hb_font_t object backing the
  *          font, or %NULL if the font does not have one
  *
  * Since: 1.44
@@ -1851,13 +1869,20 @@ pango_font_get_font_map (PangoFont *font)
 hb_font_t *
 pango_font_get_hb_font (PangoFont *font)
 {
+  PangoFontPrivate *priv = pango_font_get_instance_private (font);
+
   if (G_UNLIKELY (!font))
     return NULL;
 
-  if (PANGO_FONT_GET_CLASS (font)->get_hb_font)
-    return PANGO_FONT_GET_CLASS (font)->get_hb_font (font);
-  else
-    return NULL;
+  if (priv->hb_font)
+    return priv->hb_font;
+  else if (PANGO_FONT_GET_CLASS (font)->create_hb_font)
+    {
+      priv->hb_font = PANGO_FONT_GET_CLASS (font)->create_hb_font (font);
+      return priv->hb_font;
+    }
+
+  return hb_font_get_empty ();
 }
 
 G_DEFINE_BOXED_TYPE (PangoFontMetrics, pango_font_metrics,
diff --git a/pango/pango-font.h b/pango/pango-font.h
index d9a35885..2c7eac18 100644
--- a/pango/pango-font.h
+++ b/pango/pango-font.h
@@ -636,7 +636,7 @@ struct _PangoFontClass
                                               PangoLanguage  *language);
   PangoFontMap *        (*get_font_map)       (PangoFont      *font);
   PangoFontDescription *(*describe_absolute)  (PangoFont      *font);
-  hb_font_t *           (*get_hb_font)        (PangoFont      *font);
+  hb_font_t *           (*create_hb_font)     (PangoFont      *font);
   /*< private >*/
 
   /* Padding for future expansion */
diff --git a/pango/pangofc-font.c b/pango/pangofc-font.c
index ee51444d..fffc6e2d 100644
--- a/pango/pangofc-font.c
+++ b/pango/pangofc-font.c
@@ -89,7 +89,7 @@ static PangoFontMetrics *    pango_fc_font_get_metrics  (PangoFont        *font,
 static PangoFontMap *        pango_fc_font_get_font_map (PangoFont        *font);
 static PangoFontDescription *pango_fc_font_describe     (PangoFont        *font);
 static PangoFontDescription *pango_fc_font_describe_absolute (PangoFont        *font);
-static hb_font_t *           pango_fc_font_get_hb_font  (PangoFont        *font);
+static hb_font_t *           pango_fc_font_create_hb_font (PangoFont        *font);
 
 #define PANGO_FC_FONT_LOCK_FACE(font)  (PANGO_FC_FONT_GET_CLASS (font)->lock_face (font))
 #define PANGO_FC_FONT_UNLOCK_FACE(font)        (PANGO_FC_FONT_GET_CLASS (font)->unlock_face (font))
@@ -116,7 +116,7 @@ pango_fc_font_class_init (PangoFcFontClass *class)
   font_class->get_coverage = pango_fc_font_get_coverage;
   font_class->get_metrics = pango_fc_font_get_metrics;
   font_class->get_font_map = pango_fc_font_get_font_map;
-  font_class->get_hb_font = pango_fc_font_get_hb_font;
+  font_class->create_hb_font = pango_fc_font_create_hb_font;
 
   g_object_class_install_property (object_class, PROP_PATTERN,
                                   g_param_spec_pointer ("pattern",
@@ -1069,7 +1069,7 @@ pango_fc_font_get_raw_extents (PangoFcFont    *fcfont,
 }
 
 static hb_font_t *
-pango_fc_font_get_hb_font (PangoFont *font)
+pango_fc_font_create_hb_font (PangoFont *font)
 {
   PangoFcFont *fcfont = PANGO_FC_FONT (font);
   hb_face_t *hb_face;