Allow checking the backend type at run-time

Portable code should be allowed to check type backend currently being
used, so that it can use platform-specific API (not just Clutter's).

We don't want to go down the GDK route, with public types for
ClutterBackend and ClutterStageWindow implementations, and use the type
system, e.g.:

  #ifdef GDK_WINDOWING_X11
    if (GDK_IS_WINDOW_X11 (window))
      use_x11_api (window);
    else
  #endif
  #ifdef GDK_WINDOWING_WIN32
    if (GDK_IS_WINDOW_WIN32 (window))
      use_win32_api (window);
    else
  #endif
    g_critical ("Unsupported backend");

This system would make us expose the backend system, and we want to
still reserve us the option to change the backend system to increase its
granularity — e.g. choosing different input event systems regardless of
the windowing system.

This commit adds a simple function that checks the backend type against
a symbolic constant — the same constant string that can be used to
select the backend at run-time through the CLUTTER_BACKEND environment
variable.
This commit is contained in:
Emmanuele Bassi 2011-09-26 13:14:26 +01:00
parent a09bbffd92
commit 21a24c862e
3 changed files with 133 additions and 6 deletions

View File

@ -48,6 +48,73 @@ G_BEGIN_DECLS
#define CLUTTER_BACKEND(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), CLUTTER_TYPE_BACKEND, ClutterBackend))
#define CLUTTER_IS_BACKEND(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), CLUTTER_TYPE_BACKEND))
/**
* CLUTTER_OSX_BACKEND:
*
* Evaluates to the symbolic name of the Quartz Clutter backend.
*
* This macro should be used with clutter_check_backend().
*
* Since: 1.10
*/
#define CLUTTER_OSX_BACKEND "osx"
/**
* CLUTTER_X11_BACKEND:
*
* Evaluates to the symbolic name of the X11 Clutter backend.
*
* This macro should be used with clutter_check_backend().
*
* Since: 1.10
*/
#define CLUTTER_X11_BACKEND "x11"
/**
* CLUTTER_WIN32_BACKEND:
*
* Evaluates to the symbolic name of the Windows Clutter backend.
*
* This macro should be used with clutter_check_backend().
*
* Since: 1.10
*/
#define CLUTTER_WIN32_BACKEND "win32"
/**
* CLUTTER_EGL_NATIVE_BACKEND:
*
* Evaluates to the symbolic name of the EGL framebuffer Clutter backend.
*
* This macro should be used with clutter_check_backend().
*
* Since: 1.10
*/
#define CLUTTER_EGL_NATIVE_BACKEND "eglnative"
/**
* CLUTTER_WAYLAND_BACKEND:
*
* Evaluates to the symbolic name of the Wayland client Clutter backend.
*
* This macro should be used with clutter_check_backend().
*
* Since: 1.10
*/
#define CLUTTER_WAYLAND_BACKEND "wayland"
/**
* CLUTTER_GDK_BACKEND:
*
* Evaluates to the symbolic name of the GDK Clutter backend.
*
* This macro should be used with clutter_check_backend().
*
* Since: 1.10
*/
#define CLUTTER_GDK_BACKEND "gdk"
/**
* ClutterBackend:
*

View File

@ -1326,32 +1326,32 @@ clutter_context_get_default_unlocked (void)
backend = g_getenv ("CLUTTER_BACKEND");
#ifdef CLUTTER_WINDOWING_OSX
if (backend == NULL || strcmp (backend, "osx") == 0)
if (backend == NULL || strcmp (backend, CLUTTER_OSX_BACKEND) == 0)
ctx->backend = g_object_new (CLUTTER_TYPE_BACKEND_OSX, NULL);
else
#endif
#ifdef CLUTTER_WINDOWING_WIN32
if (backend == NULL || strcmp (backend, "win32") == 0)
if (backend == NULL || strcmp (backend, CLUTTER_WIN32_BACKEND) == 0)
ctx->backend = g_object_new (CLUTTER_TYPE_BACKEND_WIN32, NULL);
else
#endif
#ifdef CLUTTER_WINDOWING_WAYLAND
if (backend == NULL || strcmp (backend, "wayland") == 0)
if (backend == NULL || strcmp (backend, CLUTTER_WAYLAND_BACKEND) == 0)
ctx->backend = g_object_new (CLUTTER_TYPE_BACKEND_WAYLAND, NULL);
else
#endif
#ifdef CLUTTER_WINDOWING_EGL
if (backend == NULL || strcmp (backend, "eglnative") == 0)
if (backend == NULL || strcmp (backend, CLUTTER_EGL_NATIVE_BACKEND) == 0)
ctx->backend = g_object_new (CLUTTER_TYPE_BACKEND_EGLNATIVE, NULL);
else
#endif
#ifdef CLUTTER_WINDOWING_X11
if (backend == NULL || strcmp (backend, "x11") == 0)
if (backend == NULL || strcmp (backend, CLUTTER_X11_BACKEND) == 0)
ctx->backend = g_object_new (CLUTTER_TYPE_BACKEND_X11, NULL);
else
#endif
#ifdef CLUTTER_WINDOWING_GDK
if (backend == NULL || strcmp (backend, "gdk") == 0)
if (backend == NULL || strcmp (backend, CLUTTER_GDK_BACKEND) == 0)
ctx->backend = g_object_new (CLUTTER_TYPE_BACKEND_GDK, NULL);
else
#endif
@ -3610,3 +3610,61 @@ _clutter_context_get_motion_events_enabled (void)
return context->motion_events_per_actor;
}
/**
* clutter_check_backend:
* @backend_type: the name of the backend to check
*
* Checks the run-time name of the Clutter backend, using the symbolic
* macros like %CLUTTER_OSX_BACKEND or %CLUTTER_X11_BACKEND.
*
* Return value: %TRUE if the current Clutter backend is the one checked,
* and %FALSE otherwise
*
* Since: 1.10
*/
gboolean
clutter_check_backend (const char *backend_type)
{
ClutterMainContext *context = _clutter_context_get_default ();
g_return_val_if_fail (backend_type != NULL, FALSE);
#ifdef CLUTTER_WINDOWING_OSX
if (strcmp (backend_type, CLUTTER_OSX_BACKEND) == 0 &&
CLUTTER_IS_BACKEND_OSX (context->backend))
return TRUE;
else
#endif
#ifdef CLUTTER_WINDOWING_WIN32
if (strcmp (backend_type, CLUTTER_WIN32_BACKEND) == 0 &&
CLUTTER_IS_BACKEND_WIN32 (context->backend))
return TRUE;
else
#endif
#ifdef CLUTTER_WINDOWING_WAYLAND
if (strcmp (backend_type, CLUTTER_WAYLAND_BACKEND) == 0 &&
CLUTTER_IS_BACKEND_WAYLAND (context->backend))
return TRUE;
else
#endif
#ifdef CLUTTER_WINDOWING_EGL
if (strcmp (backend_type, CLUTTER_EGL_BACKEND) == 0 &&
CLUTTER_IS_BACKEND_EGL_NATIVE (context->backend))
return TRUE;
else
#endif
#ifdef CLUTTER_WINDOWING_X11
if (strcmp (backend_type, CLUTTER_X11_BACKEND) == 0 &&
CLUTTER_IS_BACKEND_X11 (context->backend))
return TRUE;
else
#endif
#ifdef CLUTTER_WINDOWING_GDK
if (strcmp (backend_type, CLUTTER_GDK_BACKEND) == 0 &&
CLUTTER_IS_BACKEND_GDK (context->backend))
return TRUE;
else
#endif
return FALSE;
}

View File

@ -195,6 +195,8 @@ gboolean clutter_check_version (guint major,
guint minor,
guint micro);
gboolean clutter_check_backend (const char *backend_type);
G_END_DECLS
#endif /* __CLUTTER_VERSION_H__ */