[gegl/gsoc2009-gpu] GeglBufferIterator: Disable iteration on GPU data when GPU acceleration is disabled

[Jerson Michael Perpetua <jperpetua src gnome org>]

commit 70ac56eb6cfdf412662a654803c0a9400b9db15f
Author: Jerson Michael Perpetua <jersonperpetua gmail com>
Date:   Mon Jul 6 05:26:34 2009 +0800

    GeglBufferIterator: Disable iteration on GPU data when GPU acceleration is disabled

 gegl/buffer/gegl-buffer-iterator.c |   18 ++++++++++++++----
 1 files changed, 14 insertions(+), 4 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer-iterator.c b/gegl/buffer/gegl-buffer-iterator.c
index 58f5f16..7e196b2 100644
--- a/gegl/buffer/gegl-buffer-iterator.c
+++ b/gegl/buffer/gegl-buffer-iterator.c
@@ -172,6 +172,7 @@ gulp:
       i->tile = NULL;
 
       i->sub_data = NULL;
+      i->gpu_data = NULL;
     }
 
   memset (&i->subrect, 0, sizeof (GeglRectangle));
@@ -290,10 +291,19 @@ gegl_buffer_iterator_add (GeglBufferIterator  *iterator,
     lock_mode |= GEGL_TILE_LOCK_READ;
   if (flags & GEGL_BUFFER_WRITE)
     lock_mode |= GEGL_TILE_LOCK_WRITE;
-  if (flags & GEGL_BUFFER_GPU_READ)
-    lock_mode |= GEGL_TILE_LOCK_GPU_READ;
-  if (flags & GEGL_BUFFER_GPU_WRITE)
-    lock_mode |= GEGL_TILE_LOCK_GPU_WRITE;
+
+  if (gegl_gpu_is_accelerated ())
+    {
+      if (flags & GEGL_BUFFER_GPU_READ)
+        lock_mode |= GEGL_TILE_LOCK_GPU_READ;
+      if (flags & GEGL_BUFFER_GPU_WRITE)
+        lock_mode |= GEGL_TILE_LOCK_GPU_WRITE;
+    }
+  else
+    /* do not allow iteration on GPU data when GPU acceleration
+     * is disabled
+     */
+    flags &= ~GEGL_BUFFER_GPU_READ & ~GEGL_BUFFER_GPU_WRITE;
 
   if (self == 0)
     {