Bug 329664 – Move gunichar_to_glyph cache from PangoCairoFcFont to

2006-04-29  Behdad Esfahbod  <behdad@gnome.org>

        Bug 329664 – Move gunichar_to_glyph cache from PangoCairoFcFont to
        PangoFcFont
        Patch from LingNing Zhang.

        * pango/pangocairo-fcfont.c (pango_cairo_fc_font_finalize),
        (pango_cairo_fc_font_glyph_extents_cache_init),
        (pango_cairo_fc_font_get_glyph_extents_cache_entry),
        (pango_cairo_fc_font_class_init), (pango_cairo_fc_font_init):
        * pango/pangofc-font.c (pango_fc_font_finalize),
        (pango_fc_font_real_get_glyph): Move gunichar->glyph cache to
        pangofc-font.c

1 files changed, 49 insertions, 10 deletions

diff --git a/pango/pangofc-font.c b/pango/pangofc-font.c
index e3585acf..2c0968d4 100644
--- a/pango/pangofc-font.c
+++ b/pango/pangofc-font.c
@@ -37,14 +37,33 @@ enum {
   PROP_PATTERN
 };
 
+typedef struct _GUnicharToGlyphCacheEntry GUnicharToGlyphCacheEntry;
+
+/* An entry in the fixed-size cache for the gunichar -> glyph mapping.
+ * The cache is indexed by the lower N bits of the gunichar (see
+ * GLYPH_CACHE_NUM_ENTRIES).  For scripts with few code points,
+ * this should provide pretty much instant lookups.
+ *
+ * The "ch" field is zero if that cache entry is invalid.
+ */
+struct _GUnicharToGlyphCacheEntry
+{
+  gunichar   ch;
+  PangoGlyph glyph;
+};
+
 typedef struct _PangoFcFontPrivate PangoFcFontPrivate;
 
 struct _PangoFcFontPrivate
 {
   PangoFcDecoder *decoder;
   gpointer context_key;
+  GUnicharToGlyphCacheEntry *char_to_glyph_cache;  
 };
 
+#define GLYPH_CACHE_NUM_ENTRIES 256 /* should be power of two */
+#define GLYPH_CACHE_MASK (GLYPH_CACHE_NUM_ENTRIES - 1)
+
 static gboolean pango_fc_font_real_has_char  (PangoFcFont *font,
 					      gunichar     wc);
 static guint    pango_fc_font_real_get_glyph (PangoFcFont *font,
@@ -69,9 +88,6 @@ static PangoFontDescription *pango_fc_font_describe     (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))
 
-
-
-
 G_DEFINE_TYPE (PangoFcFont, pango_fc_font, PANGO_TYPE_FONT)
 
 static void
@@ -134,6 +150,9 @@ pango_fc_font_finalize (GObject *object)
   if (priv->decoder)
     _pango_fc_font_set_decoder (fcfont, NULL);
 
+  if (priv->char_to_glyph_cache)
+    g_free (priv->char_to_glyph_cache);
+
   G_OBJECT_CLASS (pango_fc_font_parent_class)->finalize (object);
 }
 
@@ -505,15 +524,35 @@ pango_fc_font_real_get_glyph (PangoFcFont *font,
   FT_Face face;
   FT_UInt index;
 
-  face = PANGO_FC_FONT_LOCK_FACE (font);
-  
-  index = FcFreeTypeCharIndex (face, wc);
-  if (index > (FT_UInt)face->num_glyphs)
-    index = 0;
+  guint idx;
+  GUnicharToGlyphCacheEntry *entry;
 
-  PANGO_FC_FONT_UNLOCK_FACE (font);
+  PangoFcFontPrivate *priv = font->priv;
+
+  if (G_UNLIKELY (priv->char_to_glyph_cache == NULL))
+    {
+      priv->char_to_glyph_cache = g_new0 (GUnicharToGlyphCacheEntry, GLYPH_CACHE_NUM_ENTRIES);
+      /* Make sure all cache entries are invalid initially */
+      priv->char_to_glyph_cache[0].ch = 1; /* char 1 cannot happen in bucket 0 */
+    }
+
+  idx = wc & GLYPH_CACHE_MASK;
+  entry = priv->char_to_glyph_cache + idx;
+
+  if (entry->ch != wc)
+    {
+      face = PANGO_FC_FONT_LOCK_FACE (font);
+      index = FcFreeTypeCharIndex (face, wc);
+      if (index > (FT_UInt)face->num_glyphs)
+        index = 0;
+
+      entry->ch = wc;
+      entry->glyph = index;
+      
+      PANGO_FC_FONT_UNLOCK_FACE (font);
+    }
 
-  return index;
+  return entry->glyph;
 }
 
 /**