backend: Unify the event initialization

Input backends are, in some cases, independent from the windowing system
backends; we can initialize input handling using a model similar to what
we use for windowing backends, including an environment variable and
compile-/run-time checks.

This model allows us to remove the backend-specific init_events(), and
use a generic implementation directly inside the base ClutterBackend
class, thus further reducing the backend-specific code that every
platform has to implement.

This requires some minor surgery to every single backend, to make sure
that the function exposed to initialize the event loop is similar and
performs roughly the same operations.

1 files changed, 83 insertions, 2 deletions

diff --git a/clutter/clutter-backend.c b/clutter/clutter-backend.c
index e448a27f5..4891bffa3 100644
--- a/clutter/clutter-backend.c
+++ b/clutter/clutter-backend.c
@@ -55,6 +55,23 @@
 
 #include <cogl/cogl.h>
 
+#ifdef CLUTTER_INPUT_X11
+#include "x11/clutter-backend-x11.h"
+#endif
+#ifdef CLUTTER_INPUT_WIN32
+#include "win32/clutter-backend-win32.h"
+#endif
+#ifdef CLUTTER_INPUT_OSX
+#include "osx/clutter-backend-osx.h"
+#endif
+#ifdef CLUTTER_INPUT_EVDEV
+#include "evdev/clutter-device-manager-evdev.h"
+#endif
+#ifdef CLUTTER_INPUT_TSLIB
+/* XXX - should probably warn, here */
+#include "tslib/clutter-event-tslib.h"
+#endif
+
 G_DEFINE_ABSTRACT_TYPE (ClutterBackend, clutter_backend, G_TYPE_OBJECT);
 
 #define DEFAULT_FONT_NAME       "Sans 10"
@@ -243,6 +260,70 @@ clutter_backend_real_redraw (ClutterBackend *backend,
   _clutter_stage_window_redraw (impl);
 }
 
+static void
+clutter_backend_real_init_events (ClutterBackend *backend)
+{
+  const char *input_backend = NULL;
+
+  input_backend = g_getenv ("CLUTTER_INPUT_BACKEND");
+  if (input_backend != NULL)
+    input_backend = g_intern_string (input_backend);
+
+#ifdef CLUTTER_INPUT_X11
+  if (clutter_check_windowing_backend (CLUTTER_WINDOWING_X11) &&
+      (input_backend == NULL || input_backend == I_(CLUTTER_INPUT_X11)))
+    {
+      _clutter_backend_x11_events_init (backend);
+    }
+  else
+#endif
+#ifdef CLUTTER_INPUT_OSX
+  if (clutter_check_windowing_backend (CLUTTER_WINDOWING_OSX) &&
+      (input_backend == NULL || input_backend == I_(CLUTTER_INPUT_OSX)))
+    {
+      _clutter_backend_osx_events_init (backend);
+    }
+#endif
+#ifdef CLUTTER_INPUT_WIN32
+  if (clutter_check_windowing_backend (CLUTTER_WINDOWING_WIN32) &&
+      (input_backend == NULL || input_backend == I_(CLUTTER_INPUT_WIN32)))
+    {
+      _clutter_backend_win32_events_init (backend);
+    }
+  else
+#endif
+#ifdef CLUTTER_INPUT_GDK
+  if (clutter_check_windowing_backend (CLUTTER_WINDOWING_GDK) &&
+      (input_backend == NULL || input_backend == I_(CLUTTER_INPUT_GDK)))
+    {
+      _clutter_backend_gdk_events_init (backend);
+    }
+  else
+#endif
+#ifdef CLUTTER_INPUT_EVDEV
+  /* Evdev can be used regardless of the windowing system */
+  if (input_backend != NULL &&
+      strcmp (input_backend, CLUTTER_INPUT_EVDEV) == 0)
+    {
+      _clutter_events_evdev_init (backend);
+    }
+  else
+#endif
+#ifdef CLUTTER_INPUT_TSLIB
+  /* Tslib can be used regardless of the windowing system */
+  if (input_backend != NULL &&
+      strcmp (input_backend, CLUTTER_INPUT_TSLIB) == 0)
+    {
+      _clutter_events_tslib_init (backend);
+    }
+  else
+#endif
+  if (input_backend != NULL)
+    g_error ("Unrecognized input backend '%s'", input_backend);
+  else
+    g_error ("Unknown input backend");
+}
+
 static gboolean
 clutter_backend_real_translate_event (ClutterBackend *backend,
                                       gpointer        native,
@@ -339,6 +420,7 @@ clutter_backend_class_init (ClutterBackendClass *klass)
   klass->resolution_changed = clutter_backend_real_resolution_changed;
   klass->font_changed = clutter_backend_real_font_changed;
 
+  klass->init_events = clutter_backend_real_init_events;
   klass->translate_event = clutter_backend_real_translate_event;
   klass->ensure_context = clutter_backend_real_ensure_context;
   klass->redraw = clutter_backend_real_redraw;
@@ -591,8 +673,7 @@ _clutter_backend_init_events (ClutterBackend *backend)
   g_assert (CLUTTER_IS_BACKEND (backend));
 
   klass = CLUTTER_BACKEND_GET_CLASS (backend);
-  if (klass->init_events)
-    klass->init_events (backend);
+  klass->init_events (backend);
 }
 
 gfloat