Implement accessors for the color bits in a framebuffer

Instead of using cogl_get_bitmasks() to query the GL machinery for the
size of the color bits, we should store the values inside the
CoglFramebuffer object and query them the first time we set the framebuffer
as the current one.

Currently, cogl_get_bitmasks() is re-implemented in terms of
cogl_framebuffer_get_*_bits(). As soon as we are able to expose the
CoglOnscreen framebuffer object in the public API we'll be able to
deprecate cogl_get_bitmasks() altogether.

http://bugzilla.openedhand.com/show_bug.cgi?id=2094

clutter/cogl/cogl/cogl-context.c

@@ -100,6 +100,7 @@ cogl_create_context (void)
   _context->n_texcoord_arrays_enabled = 0;
 
   _context->framebuffer_stack = _cogl_create_framebuffer_stack ();
+
   window_buffer = _cogl_onscreen_new ();
   cogl_set_framebuffer (window_buffer);
   /* XXX: the deprecated _cogl_set_draw_buffer API expects to

clutter/cogl/cogl/cogl-framebuffer-private.h

@@ -48,6 +48,12 @@ typedef struct
   int                 viewport_height;
 
   CoglClipState       clip_state;
+
+  gboolean            dirty_bitmasks;
+  int                 red_bits;
+  int                 blue_bits;
+  int                 green_bits;
+  int                 alpha_bits;
 } CoglFramebuffer;
 
 #define COGL_FRAMEBUFFER(X) ((CoglFramebuffer *)(X))
@@ -71,12 +77,16 @@ typedef struct _CoglOnscreen
 
 void
 _cogl_framebuffer_state_init (void);
+
 int
 _cogl_framebuffer_get_width (CoglHandle handle);
+
 int
 _cogl_framebuffer_get_height (CoglHandle handle);
+
 CoglClipState *
 _cogl_framebuffer_get_clip_state (CoglHandle handle);
+
 void
 _cogl_framebuffer_set_viewport (CoglHandle handle,
                                 int x,
@@ -85,16 +95,22 @@ _cogl_framebuffer_set_viewport (CoglHandle handle,
                                 int height);
 int
 _cogl_framebuffer_get_viewport_x (CoglHandle handle);
+
 int
 _cogl_framebuffer_get_viewport_y (CoglHandle handle);
+
 int
 _cogl_framebuffer_get_viewport_width (CoglHandle handle);
+
 int
 _cogl_framebuffer_get_viewport_height (CoglHandle handle);
+
 void
 _cogl_framebuffer_get_viewport4fv (CoglHandle handle, int *viewport);
+
 CoglMatrixStack *
 _cogl_framebuffer_get_modelview_stack (CoglHandle handle);
+
 CoglMatrixStack *
 _cogl_framebuffer_get_projection_stack (CoglHandle handle);
 
@@ -116,8 +132,10 @@ _cogl_onscreen_new (void);
 
 CoglHandle
 _cogl_get_framebuffer (void);
+
 GSList *
 _cogl_create_framebuffer_stack (void);
+
 void
 _cogl_free_framebuffer_stack (GSList *stack);
 

clutter/cogl/cogl/cogl-framebuffer.c

@@ -130,6 +130,8 @@ _cogl_framebuffer_init (CoglFramebuffer *framebuffer,
   framebuffer->modelview_stack  = _cogl_matrix_stack_new ();
   framebuffer->projection_stack = _cogl_matrix_stack_new ();
 
+  framebuffer->dirty_bitmasks   = TRUE;
+
   /* Initialise the clip stack */
   _cogl_clip_state_init (&framebuffer->clip_state);
 }
@@ -248,6 +250,20 @@ _cogl_framebuffer_get_projection_stack (CoglHandle handle)
   return framebuffer->projection_stack;
 }
 
+static inline void
+_cogl_framebuffer_init_bits (CoglFramebuffer *framebuffer)
+{
+  if (G_LIKELY (!framebuffer->dirty_bitmasks))
+    return;
+
+  GE( glGetIntegerv (GL_RED_BITS,   &framebuffer->red_bits)   );
+  GE( glGetIntegerv (GL_GREEN_BITS, &framebuffer->green_bits) );
+  GE( glGetIntegerv (GL_BLUE_BITS,  &framebuffer->blue_bits)  );
+  GE( glGetIntegerv (GL_ALPHA_BITS, &framebuffer->alpha_bits) );
+
+  framebuffer->dirty_bitmasks = FALSE;
+}
+
 static gboolean
 try_creating_fbo (CoglOffscreen *offscreen,
                   TryFBOFlags flags,
@@ -552,6 +568,8 @@ _cogl_set_framebuffer_real (CoglFramebuffer *framebuffer)
   _cogl_matrix_stack_dirty (framebuffer->modelview_stack);
   _cogl_matrix_stack_dirty (framebuffer->projection_stack);
   _cogl_clip_state_dirty (&framebuffer->clip_state);
+
+  _cogl_framebuffer_init_bits (framebuffer);
 }
 
 void
@@ -707,3 +725,42 @@ _cogl_framebuffer_flush_state (CoglHandle handle,
                                   COGL_MATRIX_PROJECTION);
 }
 
+int
+cogl_framebuffer_get_red_bits (CoglHandle framebuffer)
+{
+  CoglFramebuffer *fb = COGL_FRAMEBUFFER (framebuffer);
+
+  _cogl_framebuffer_init_bits (fb);
+
+  return fb->red_bits;
+}
+
+int
+cogl_framebuffer_get_green_bits (CoglHandle framebuffer)
+{
+  CoglFramebuffer *fb = COGL_FRAMEBUFFER (framebuffer);
+
+  _cogl_framebuffer_init_bits (fb);
+
+  return fb->green_bits;
+}
+
+int
+cogl_framebuffer_get_blue_bits (CoglHandle framebuffer)
+{
+  CoglFramebuffer *fb = COGL_FRAMEBUFFER (framebuffer);
+
+  _cogl_framebuffer_init_bits (fb);
+
+  return fb->blue_bits;
+}
+
+int
+cogl_framebuffer_get_alpha_bits (CoglHandle framebuffer)
+{
+  CoglFramebuffer *fb = COGL_FRAMEBUFFER (framebuffer);
+
+  _cogl_framebuffer_init_bits (fb);
+
+  return fb->alpha_bits;
+}

clutter/cogl/cogl/cogl.c

@@ -533,31 +533,21 @@ cogl_get_bitmasks (int *red,
                    int *blue,
                    int *alpha)
 {
-  GLint value;
+  CoglHandle framebuffer;
+
+  framebuffer = _cogl_get_framebuffer ();
 
   if (red)
-    {
-      GE( glGetIntegerv(GL_RED_BITS, &value) );
-      *red = value;
-    }
+    *red = cogl_framebuffer_get_red_bits (framebuffer);
 
   if (green)
-    {
-      GE( glGetIntegerv(GL_GREEN_BITS, &value) );
-      *green = value;
-    }
+    *green = cogl_framebuffer_get_green_bits (framebuffer);
 
   if (blue)
-    {
-      GE( glGetIntegerv(GL_BLUE_BITS, &value) );
-      *blue = value;
-    }
+    *blue = cogl_framebuffer_get_blue_bits (framebuffer);
 
   if (alpha)
-    {
-      GE( glGetIntegerv(GL_ALPHA_BITS, &value ) );
-      *alpha = value;
-    }
+    *alpha = cogl_framebuffer_get_alpha_bits (framebuffer);
 }
 
 void

clutter/cogl/cogl/cogl.h

@@ -159,6 +159,58 @@ cogl_get_bitmasks (int *red,
                    int *blue,
                    int *alpha);
 
+/**
+ * cogl_framebuffer_get_red_bits:
+ * @framebuffer: a handle for a framebuffer
+ *
+ * Retrieves the number of red bits of @framebuffer
+ *
+ * Return value: the number of bits
+ *
+ * Since: 1.4
+ */
+int
+cogl_framebuffer_get_red_bits (CoglHandle framebuffer);
+
+/**
+ * cogl_framebuffer_get_green_bits:
+ * @framebuffer: a handle for a framebuffer
+ *
+ * Retrieves the number of green bits of @framebuffer
+ *
+ * Return value: the number of bits
+ *
+ * Since: 1.4
+ */
+int
+cogl_framebuffer_get_green_bits (CoglHandle framebuffer);
+
+/**
+ * cogl_framebuffer_get_blue_bits:
+ * @framebuffer: a handle for a framebuffer
+ *
+ * Retrieves the number of blue bits of @framebuffer
+ *
+ * Return value: the number of bits
+ *
+ * Since: 1.4
+ */
+int
+cogl_framebuffer_get_blue_bits (CoglHandle framebuffer);
+
+/**
+ * cogl_framebuffer_get_alpha_bits:
+ * @framebuffer: a handle for a framebuffer
+ *
+ * Retrieves the number of alpha bits of @framebuffer
+ *
+ * Return value: the number of bits
+ *
+ * Since: 1.4
+ */
+int
+cogl_framebuffer_get_alpha_bits (CoglHandle framebuffer);
+
 /**
  * cogl_perspective:
  * @fovy: Vertical of view angle in degrees.