From 0a0a59cf7bdc5d4ee3639923f19cb57bf666815b Mon Sep 17 00:00:00 2001
From: Damien Lespiau <damien.lespiau@intel.com>
Date: Sat, 28 Aug 2010 12:06:11 +0100
Subject: [PATCH] cex100: Add an API to configure the buffering mode of the GDL
 plane

GDL planes can be double or triple buffered. Let the user choose between
the two modes befored initalizing Clutter.
---
 clutter/egl/clutter-backend-cex100.c       | 21 +++++++++--------
 clutter/egl/clutter-cex100.h.in            | 27 ++++++++++++++++++++++
 doc/reference/clutter/clutter-sections.txt |  2 ++
 3 files changed, 40 insertions(+), 10 deletions(-)

diff --git a/clutter/egl/clutter-backend-cex100.c b/clutter/egl/clutter-backend-cex100.c
index d93d5bc1b..caf31a611 100644
--- a/clutter/egl/clutter-backend-cex100.c
+++ b/clutter/egl/clutter-backend-cex100.c
@@ -38,6 +38,7 @@
 #include "clutter-cex100.h"
 
 static gdl_plane_id_t gdl_plane = GDL_PLANE_ID_UPP_C;
+static guint gdl_n_buffers = CLUTTER_CEX100_TRIPLE_BUFFERING;
 
 G_DEFINE_TYPE (ClutterBackendCex100,
                clutter_backend_cex100,
@@ -122,17 +123,8 @@ gdl_plane_init (gdl_display_id_t   dpy,
   if (rc == GDL_SUCCESS)
     rc = gdl_plane_set_attr (GDL_PLANE_DST_RECT, &dstRect);
 
-#if 0
-  /*
-   * Change the number of back buffers for the eglWindowSurface, Default
-   * value is 3, could be changed to 2, means one front buffer and one back
-   * buffer.
-   *
-   * TODO: Make a new API to tune that;
-   */
   if (rc == GDL_SUCCESS)
-    rc = gdl_plane_set_uint (GDL_PLANE_NUM_GFX_SURFACES, 2);
-#endif
+    rc = gdl_plane_set_uint (GDL_PLANE_NUM_GFX_SURFACES, gdl_n_buffers);
 
   if (rc == GDL_SUCCESS)
     rc = gdl_plane_config_end (GDL_FALSE);
@@ -365,3 +357,12 @@ clutter_cex100_set_plane (gdl_plane_id_t plane)
 
   gdl_plane = plane;
 }
+
+void
+clutter_cex100_set_buffering_mode (ClutterCex100BufferingMode mode)
+{
+  g_return_if_fail (mode == CLUTTER_CEX100_DOUBLE_BUFFERING ||
+                    mode == CLUTTER_CEX100_TRIPLE_BUFFERING);
+
+  gdl_n_buffers = mode;
+}
diff --git a/clutter/egl/clutter-cex100.h.in b/clutter/egl/clutter-cex100.h.in
index 835365f42..54a53738b 100644
--- a/clutter/egl/clutter-cex100.h.in
+++ b/clutter/egl/clutter-cex100.h.in
@@ -59,6 +59,33 @@ G_BEGIN_DECLS
  */
 void clutter_cex100_set_plane (gdl_plane_id_t plane);
 
+/**
+ * ClutterCex100BufferingMode:
+ * @CLUTTER_CEX100_DOUBLE_BUFFERING: The GDL plane will be double buffered
+ * @CLUTTER_CEX100_TRIPLE_BUFFERING: The GDL plane will be triple buffered
+ *
+ * Enum passed to clutter_cex100_set_buffering_mode().
+ */
+typedef enum /*< prefix=CLUTTER_CEX100 >*/
+{
+  CLUTTER_CEX100_DOUBLE_BUFFERING = 2,
+  CLUTTER_CEX100_TRIPLE_BUFFERING = 3
+} ClutterCex100BufferingMode;
+
+/**
+ * clutter_cex100_set_buffering_mode:
+ * @mode: a #ClutterCex100BufferingMode
+ *
+ * Configure the buffering mode of the underlying GDL plane. The GDL
+ * surface used by Clutter to draw can be backed up by either one or two
+ * back buffers thus being double or triple buffered, respectively.
+ *
+ * Clutter defaults to #CLUTTER_CEX100_TRIPLE_BUFFERING.
+ *
+ * <note>This function has to be called before clutter_init()</note>
+ */
+void clutter_cex100_set_buffering_mode (ClutterCex100BufferingMode mode);
+
 G_END_DECLS
 
 #endif /* __CLUTTER_CEX100_H__ */
diff --git a/doc/reference/clutter/clutter-sections.txt b/doc/reference/clutter/clutter-sections.txt
index 7844a8c0c..3059a74fe 100644
--- a/doc/reference/clutter/clutter-sections.txt
+++ b/doc/reference/clutter/clutter-sections.txt
@@ -1839,6 +1839,8 @@ clutter_eglx_display
 <TITLE>Intel CE3100, CE4100 Specific Support</TITLE>
 <FILE>clutter-cex100</FILE>
 clutter_cex100_set_plane
+ClutterCex100BufferingMode
+clutter_cex100_set_buffering_mode
 </SECTION>
 
 <SECTION>