[cogl] framebuffer: make _swap_region coords top-left relative

[Robert Bragg <rbragg src gnome org>]

commit 3a2f94045e0c4e423e14b8823535512271f2d9bf
Author: Robert Bragg <robert linux intel com>
Date:   Fri Jul 22 12:23:40 2011 +0100

    framebuffer: make _swap_region coords top-left relative
    
    Cogl aims to consistently put the origin of 2D objects at the top-left
    instead of the bottom left as OpenGL does, but there was an oversight
    and the experimental cogl_framebuffer_swap_region API was accepting
    coordinates relative to the bottom left. Cogl will now flip the user's
    given rectangles to be relative to the bottom of the framebufffer before
    sending them to APIs like glXCopySubBuffer and glBlitFramebuffer.
    
    Reviewed-by: Neil Roberts <neil linux intel com>

 cogl/cogl-framebuffer.c           |    2 +-
 cogl/cogl-framebuffer.h           |    2 +-
 cogl/winsys/cogl-winsys-egl.c     |   16 +++++++++++++++-
 cogl/winsys/cogl-winsys-glx.c     |   15 ++++++++++++++-
 cogl/winsys/cogl-winsys-private.h |    2 +-
 5 files changed, 32 insertions(+), 5 deletions(-)
---
diff --git a/cogl/cogl-framebuffer.c b/cogl/cogl-framebuffer.c
index a7a442c..4a45e75 100644
--- a/cogl/cogl-framebuffer.c
+++ b/cogl/cogl-framebuffer.c
@@ -1666,7 +1666,7 @@ cogl_framebuffer_swap_buffers (CoglFramebuffer *framebuffer)
 
 void
 cogl_framebuffer_swap_region (CoglFramebuffer *framebuffer,
-                              int *rectangles,
+                              const int *rectangles,
                               int n_rectangles)
 {
   /* FIXME: we shouldn't need to flush *all* journals here! */
diff --git a/cogl/cogl-framebuffer.h b/cogl/cogl-framebuffer.h
index 9619f01..fb69da4 100644
--- a/cogl/cogl-framebuffer.h
+++ b/cogl/cogl-framebuffer.h
@@ -333,7 +333,7 @@ cogl_framebuffer_swap_buffers (CoglFramebuffer *framebuffer);
 #define cogl_framebuffer_swap_region cogl_framebuffer_swap_region_EXP
 void
 cogl_framebuffer_swap_region (CoglFramebuffer *framebuffer,
-                              int *rectangles,
+                              const int *rectangles,
                               int n_rectangles);
 
 
diff --git a/cogl/winsys/cogl-winsys-egl.c b/cogl/winsys/cogl-winsys-egl.c
index 08cd354..35230fc 100644
--- a/cogl/winsys/cogl-winsys-egl.c
+++ b/cogl/winsys/cogl-winsys-egl.c
@@ -1512,12 +1512,26 @@ _cogl_winsys_onscreen_bind (CoglOnscreen *onscreen)
 
 static void
 _cogl_winsys_onscreen_swap_region (CoglOnscreen *onscreen,
-                                   int *rectangles,
+                                   const int *user_rectangles,
                                    int n_rectangles)
 {
   CoglContext *context = COGL_FRAMEBUFFER (onscreen)->context;
   CoglRendererEGL *egl_renderer = context->display->renderer->winsys;
   CoglOnscreenEGL *egl_onscreen = onscreen->winsys;
+  CoglFramebuffer *framebuffer = COGL_FRAMEBUFFER (onscreen);
+  int framebuffer_height  = cogl_framebuffer_get_height (framebuffer);
+  int *rectangles = g_alloca (sizeof (int) * n_rectangles * 4);
+  int i;
+
+  /* eglSwapBuffersRegion expects rectangles relative to the bottom left corner
+   * but we are given rectangles relative to the top left so we need to flip
+   * them... */
+  memcpy (rectangles, user_rectangles, sizeof (int) * n_rectangles * 4);
+  for (i = 0; i < n_rectangles; i++)
+    {
+      int *rect = &rectangles[4 * i];
+      rect[1] = framebuffer_height - rect[1] - rect[3];
+    }
 
   if (egl_renderer->pf_eglSwapBuffersRegion (egl_renderer->edpy,
                                              egl_onscreen->egl_surface,
diff --git a/cogl/winsys/cogl-winsys-glx.c b/cogl/winsys/cogl-winsys-glx.c
index 0a2fe00..b50af55 100644
--- a/cogl/winsys/cogl-winsys-glx.c
+++ b/cogl/winsys/cogl-winsys-glx.c
@@ -1114,7 +1114,7 @@ _cogl_winsys_get_vsync_counter (void)
 
 static void
 _cogl_winsys_onscreen_swap_region (CoglOnscreen *onscreen,
-                                   int *rectangles,
+                                   const int *user_rectangles,
                                    int n_rectangles)
 {
   CoglFramebuffer *framebuffer = COGL_FRAMEBUFFER (onscreen);
@@ -1128,6 +1128,19 @@ _cogl_winsys_onscreen_swap_region (CoglOnscreen *onscreen,
   guint32 end_frame_vsync_counter = 0;
   gboolean have_counter;
   gboolean can_wait;
+  int framebuffer_height =  cogl_framebuffer_get_height (framebuffer);
+  int *rectangles = g_alloca (sizeof (int) * n_rectangles * 4);
+  int i;
+
+  /* glXCopySubBuffer expects rectangles relative to the bottom left corner but
+   * we are given rectangles relative to the top left so we need to flip
+   * them... */
+  memcpy (rectangles, user_rectangles, sizeof (int) * n_rectangles * 4);
+  for (i = 0; i < n_rectangles; i++)
+    {
+      int *rect = &rectangles[4 * i];
+      rect[1] = framebuffer_height - rect[1] - rect[3];
+    }
 
   _cogl_framebuffer_flush_state (framebuffer,
                                  framebuffer,
diff --git a/cogl/winsys/cogl-winsys-private.h b/cogl/winsys/cogl-winsys-private.h
index 88df22d..dbc4097 100644
--- a/cogl/winsys/cogl-winsys-private.h
+++ b/cogl/winsys/cogl-winsys-private.h
@@ -107,7 +107,7 @@ typedef struct _CoglWinsysVtable
 
   void
   (*onscreen_swap_region) (CoglOnscreen *onscreen,
-                           int *rectangles,
+                           const int *rectangles,
                            int n_rectangles);
 
 #ifdef COGL_HAS_EGL_SUPPORT