[gegl] buffer: cache the vfunc in instance

[Ãyvind KolÃs <ok src gnome org>]

commit 6fde478a8c541555d08966ab3ca5065d6772cfc7
Author: Ãyvind KolÃs <pippin gimp org>
Date:   Sun Jul 3 17:07:58 2011 +0100

    buffer: cache the vfunc in instance
    
    Slight speedup of sampler dispatch.

 gegl/buffer/gegl-buffer.h  |    1 +
 gegl/buffer/gegl-sampler.c |   15 ++-------------
 gegl/buffer/gegl-sampler.h |   10 ++++++++++
 3 files changed, 13 insertions(+), 13 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer.h b/gegl/buffer/gegl-buffer.h
index 78f76f6..58a37c4 100644
--- a/gegl/buffer/gegl-buffer.h
+++ b/gegl/buffer/gegl-buffer.h
@@ -382,6 +382,7 @@ GeglSampler *
 gegl_buffer_sampler_new (GeglBuffer       *buffer,
                          Babl             *format,
                          GeglInterpolation interpolation);
+
 void  gegl_sampler_set_scale   (GeglSampler *self,
                                 GeglMatrix2 *scale);
 void  gegl_sampler_get         (GeglSampler *self,
diff --git a/gegl/buffer/gegl-sampler.c b/gegl/buffer/gegl-sampler.c
index 0e2b48b..b7d2676 100644
--- a/gegl/buffer/gegl-sampler.c
+++ b/gegl/buffer/gegl-sampler.c
@@ -122,18 +122,7 @@ gegl_sampler_get (GeglSampler *self,
                   GeglMatrix2 *scale,
                   void        *output)
 {
-  GeglSamplerClass *klass;
-
-#if 0  /* avoiding expensive typecheck here */
-  g_return_if_fail (GEGL_IS_SAMPLER (self));
-#endif
-
-  self->x = x;
-  self->y = y;
-
-  klass = GEGL_SAMPLER_GET_CLASS (self); /*XXX: bottleneck, store the vfunc cached
-                                                in the instance instead  */
-  klass->get (self, x, y, scale, output);
+  self->get (self, x, y, scale, output);
 }
 
 void
@@ -166,7 +155,7 @@ gegl_sampler_prepare (GeglSampler *self)
       self->cache_buffer = NULL;
     }
 #endif
-
+  self->get = klass->get; /* cache the sampler in the instance */
 }
 
 void
diff --git a/gegl/buffer/gegl-sampler.h b/gegl/buffer/gegl-sampler.h
index 0fef155..78e2fe5 100644
--- a/gegl/buffer/gegl-sampler.h
+++ b/gegl/buffer/gegl-sampler.h
@@ -49,6 +49,16 @@ struct _GeglSampler
   GeglRectangle  sampler_rectangle[GEGL_SAMPLER_MIPMAP_LEVELS];
   gdouble        x; /* mirrors the currently requested */
   gdouble        y; /* coordinates in the instance     */
+
+  /* we cache the getter in the instance, (being able to return the
+     function pointer itself and cache it outside the calling loop
+     would be even quicker.
+   */
+  void (* get)       (GeglSampler *self,
+                      gdouble      x,
+                      gdouble      y,
+                      GeglMatrix2 *scale,
+                      void        *output);
 };
 
 struct _GeglSamplerClass