Add internal _cogl_init() function

This adds a _cogl_init function for Cogl that we expect to be the first
thing called before anything else is done with Cogl. It's not a public
API so it's expected that all entry points for Cogl that might be the
first function used should call _cogl_init().

We currently call _cogl_init() in these functions:
  cogl_renderer_new
  cogl_display_new
  cogl_context_new
  cogl_android_set_native_window

_cogl_init() can be called multiple times, and only the first call has
any affect.

For example _cogl_init() gives us a place check and parse the COGL_DEBUG
environment variable.

Since we don't have any need to parse command line arguments (we can
always get user configuration options from the environment) our init
function doesn't require argc/argv pointers.

By saying up front that we aren't interested in command line arguments
that means we can avoid the mess that is GOption based library
initialization which is extremely fragile due to its lack of dependency
tracking between modules.

Signed-off-by: Neil Roberts <neil@linux.intel.com>

cogl/cogl-context.c

@@ -111,6 +111,8 @@ cogl_context_new (CoglDisplay *display,
   const CoglWinsysVtable *winsys;
   int i;
 
+  _cogl_init ();
+
 #ifdef COGL_ENABLE_PROFILE
   /* We need to be absolutely sure that uprof has been initialized
    * before calling _cogl_uprof_init. uprof_init (NULL, NULL)

cogl/cogl-debug.c

@@ -28,10 +28,10 @@
 #include <stdlib.h>
 #include <glib/gi18n-lib.h>
 
+#include "cogl.h"
+#include "cogl-private.h"
 #include "cogl-debug.h"
 
-#ifdef COGL_ENABLE_DEBUG
-
 /* XXX: If you add a debug option, please also add an option
  * definition to cogl-debug-options.h. This will enable us - for
  * example - to emit a "help" description for the option.
@@ -176,6 +176,7 @@ _cogl_parse_debug_string (const char *value,
     }
 }
 
+#ifdef COGL_ENABLE_DEBUG
 static gboolean
 cogl_arg_debug_cb (const char *key,
                    const char *value,
@@ -209,13 +210,9 @@ static GOptionEntry cogl_args[] = {
   { NULL, },
 };
 
-static gboolean
-pre_parse_hook (GOptionContext  *context,
-                GOptionGroup    *group,
-                gpointer         data,
-                GError         **error)
+void
+_cogl_debug_check_environment (void)
 {
-#ifdef COGL_ENABLE_DEBUG
   const char *env_string;
 
   env_string = g_getenv ("COGL_DEBUG");
@@ -226,11 +223,22 @@ pre_parse_hook (GOptionContext  *context,
                                 FALSE /* don't ignore help */);
       env_string = NULL;
     }
-#endif /* COGL_ENABLE_DEBUG */
+}
+
+static gboolean
+pre_parse_hook (GOptionContext  *context,
+                GOptionGroup    *group,
+                gpointer         data,
+                GError         **error)
+{
+  _cogl_init ();
 
   return TRUE;
 }
 
+/* XXX: GOption based library initialization is not reliable because the
+ * GOption API has no way to represent dependencies between libraries.
+ */
 GOptionGroup *
 cogl_get_option_group (void)
 {

cogl/cogl-debug.h

@@ -116,6 +116,9 @@ extern GHashTable *_cogl_debug_instances;
 
 #endif /* COGL_ENABLE_DEBUG */
 
+void
+_cogl_debug_check_environment (void);
+
 G_END_DECLS
 
 #endif /* __COGL_DEBUG_H__ */

cogl/cogl-display.c

@@ -29,6 +29,7 @@
 #endif
 
 #include "cogl.h"
+#include "cogl-private.h"
 #include "cogl-object.h"
 
 #include "cogl-display-private.h"
@@ -70,6 +71,8 @@ cogl_display_new (CoglRenderer *renderer,
   CoglDisplay *display = g_slice_new0 (CoglDisplay);
   GError *error = NULL;
 
+  _cogl_init ();
+
   display->renderer = renderer;
   if (renderer)
     cogl_object_ref (renderer);

cogl/cogl-private.h

@@ -48,6 +48,9 @@ _cogl_read_pixels_with_rowstride (int x,
                                   guint8 *pixels,
                                   int rowstride);
 
+void
+_cogl_init (void);
+
 G_END_DECLS
 
 #endif /* __COGL_PRIVATE_H__ */

cogl/cogl-renderer.c

@@ -33,6 +33,7 @@
 
 #include "cogl.h"
 #include "cogl-internal.h"
+#include "cogl-private.h"
 #include "cogl-object.h"
 
 #include "cogl-renderer.h"
@@ -112,6 +113,8 @@ cogl_renderer_new (void)
 {
   CoglRenderer *renderer = g_new0 (CoglRenderer, 1);
 
+  _cogl_init ();
+
   renderer->connected = FALSE;
   renderer->event_filters = NULL;
 

cogl/cogl.c

@@ -1088,3 +1088,17 @@ _cogl_error_quark (void)
 {
   return g_quark_from_static_string ("cogl-error-quark");
 }
+
+void
+_cogl_init (void)
+{
+  static gsize init_status = 0;
+
+  if (g_once_init_enter (&init_status))
+    {
+      g_type_init ();
+
+      _cogl_debug_check_environment ();
+      g_once_init_leave (&init_status, 1);
+    }
+}

cogl/winsys/cogl-winsys-egl.c

@@ -223,6 +223,8 @@ static ANativeWindow *android_native_window;
 void
 cogl_android_set_native_window (ANativeWindow *window)
 {
+  _cogl_init ();
+
   android_native_window = window;
 }
 #endif