compositor: Refactor backend-specific code into MetaCompositor vfuncs

Do these Wayland operations (that apply on both native and nested backends)
in the MetaCompositorServer subclass. We want to add more backend specific
behavior here in the future.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1659>

src/compositor/compositor-private.h

@@ -32,6 +32,8 @@ struct _MetaCompositorClass
                           MetaWindow     *window);
   int64_t (* monotonic_to_high_res_xserver_time) (MetaCompositor *compositor,
                                                   int64_t         time_us);
+  void (* grab_begin) (MetaCompositor *compositor);
+  void (* grab_end) (MetaCompositor *compositor);
 };
 
 gboolean meta_compositor_do_manage (MetaCompositor  *compositor,

src/compositor/compositor.c

@@ -56,7 +56,6 @@
 
 #include <X11/extensions/Xcomposite.h>
 
-#include "backends/meta-dnd-private.h"
 #include "backends/x11/meta-backend-x11.h"
 #include "backends/x11/meta-event-x11.h"
 #include "backends/x11/meta-stage-x11.h"
@@ -66,7 +65,6 @@
 #include "compositor/meta-window-actor-x11.h"
 #include "compositor/meta-window-actor-private.h"
 #include "compositor/meta-window-group-private.h"
-#include "core/display-private.h"
 #include "core/frame.h"
 #include "core/util-private.h"
 #include "core/window-private.h"
@@ -384,6 +382,18 @@ grab_devices (MetaModalOptions  options,
   return FALSE;
 }
 
+static void
+meta_compositor_grab_begin (MetaCompositor *compositor)
+{
+  META_COMPOSITOR_GET_CLASS (compositor)->grab_begin (compositor);
+}
+
+static void
+meta_compositor_grab_end (MetaCompositor *compositor)
+{
+  META_COMPOSITOR_GET_CLASS (compositor)->grab_end (compositor);
+}
+
 gboolean
 meta_begin_modal_for_plugin (MetaCompositor   *compositor,
                              MetaPlugin       *plugin,
@@ -431,15 +441,7 @@ meta_begin_modal_for_plugin (MetaCompositor   *compositor,
                          meta_plugin_get_display (plugin),
                          display->grab_window, display->grab_op);
 
-  if (meta_is_wayland_compositor ())
+  meta_compositor_grab_begin (compositor);
-    {
-      meta_display_sync_wayland_input_focus (display);
-      meta_display_cancel_touch (display);
-
-#ifdef HAVE_WAYLAND
-      meta_dnd_wayland_handle_begin_modal (compositor);
-#endif
-    }
 
   return TRUE;
 }
@@ -467,13 +469,7 @@ meta_end_modal_for_plugin (MetaCompositor *compositor,
   meta_backend_ungrab_device (backend, META_VIRTUAL_CORE_POINTER_ID, timestamp);
   meta_backend_ungrab_device (backend, META_VIRTUAL_CORE_KEYBOARD_ID, timestamp);
 
-#ifdef HAVE_WAYLAND
+  meta_compositor_grab_end (compositor);
-  if (meta_is_wayland_compositor ())
-    {
-      meta_dnd_wayland_handle_end_modal (compositor);
-      meta_display_sync_wayland_input_focus (display);
-    }
-#endif
 
   g_signal_emit_by_name (display, "grab-op-end",
                          meta_plugin_get_display (plugin),

src/compositor/meta-compositor-server.c

@@ -20,7 +20,9 @@
 
 #include "config.h"
 
+#include "backends/meta-dnd-private.h"
 #include "compositor/meta-compositor-server.h"
+#include "core/display-private.h"
 
 G_DEFINE_TYPE (MetaCompositorServer, meta_compositor_server, META_TYPE_COMPOSITOR)
 
@@ -43,6 +45,32 @@ meta_compositor_server_monotonic_to_high_res_xserver_time (MetaCompositor *compo
   return meta_translate_to_high_res_xserver_time (monotonic_time_us);
 }
 
+static void
+meta_compositor_server_grab_begin (MetaCompositor *compositor)
+{
+  MetaDisplay *display;
+
+  display = meta_compositor_get_display (compositor);
+  meta_display_sync_wayland_input_focus (display);
+  meta_display_cancel_touch (display);
+
+#ifdef HAVE_WAYLAND
+  meta_dnd_wayland_handle_begin_modal (compositor);
+#endif
+}
+
+static void
+meta_compositor_server_grab_end (MetaCompositor *compositor)
+{
+  MetaDisplay *display;
+
+  display = meta_compositor_get_display (compositor);
+#ifdef HAVE_WAYLAND
+  meta_dnd_wayland_handle_end_modal (compositor);
+#endif
+  meta_display_sync_wayland_input_focus (display);
+}
+
 MetaCompositorServer *
 meta_compositor_server_new (MetaDisplay *display,
                             MetaBackend *backend)
@@ -67,4 +95,6 @@ meta_compositor_server_class_init (MetaCompositorServerClass *klass)
   compositor_class->unmanage = meta_compositor_server_unmanage;
   compositor_class->monotonic_to_high_res_xserver_time =
    meta_compositor_server_monotonic_to_high_res_xserver_time;
+  compositor_class->grab_begin = meta_compositor_server_grab_begin;
+  compositor_class->grab_end = meta_compositor_server_grab_end;
 }

src/compositor/meta-compositor-x11.c

@@ -439,6 +439,16 @@ meta_compositor_x11_monotonic_to_high_res_xserver_time (MetaCompositor *composit
   return monotonic_time_us + compositor_x11->xserver_time_offset_us;
 }
 
+static void
+meta_compositor_x11_grab_begin (MetaCompositor *compositor)
+{
+}
+
+static void
+meta_compositor_x11_grab_end (MetaCompositor *compositor)
+{
+}
+
 Window
 meta_compositor_x11_get_output_xwindow (MetaCompositorX11 *compositor_x11)
 {
@@ -508,4 +518,6 @@ meta_compositor_x11_class_init (MetaCompositorX11Class *klass)
   compositor_class->remove_window = meta_compositor_x11_remove_window;
   compositor_class->monotonic_to_high_res_xserver_time =
    meta_compositor_x11_monotonic_to_high_res_xserver_time;
+  compositor_class->grab_begin = meta_compositor_x11_grab_begin;
+  compositor_class->grab_end = meta_compositor_x11_grab_end;
 }