[mutter] clutter-seat: Handle device events and emit signals

[Robert Mader <rmader src gnome org>]

commit cf67c54f87e7ae035a6bf0f19fd37e1751af41d1
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Fri Jul 17 17:40:12 2020 +0200

    clutter-seat: Handle device events and emit signals
    
    Clutter device events are special events coming from the backend when an
    input device is added or removed.
    
    When such events are processed, we should make the seat to handle them by
    calling vfunc that can be implemented by each backend and eventually
    emitting the appropriate signal.
    
    If a device is removed, we can also safely dispose it, as it can be
    considered stale at this point.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1371

 clutter/clutter/clutter-main.c | 11 +++++++++++
 clutter/clutter/clutter-seat.c | 40 ++++++++++++++++++++++++++++++++++++++++
 clutter/clutter/clutter-seat.h |  6 ++++++
 3 files changed, 57 insertions(+)
---
diff --git a/clutter/clutter/clutter-main.c b/clutter/clutter/clutter-main.c
index 2fa3d39ce0..a2adc0d0fc 100644
--- a/clutter/clutter/clutter-main.c
+++ b/clutter/clutter/clutter-main.c
@@ -1954,6 +1954,17 @@ _clutter_process_event_details (ClutterActor        *stage,
       case CLUTTER_CLIENT_MESSAGE:
         break;
 
+      case CLUTTER_DEVICE_ADDED:
+      case CLUTTER_DEVICE_REMOVED:
+        if (!_clutter_event_process_filters (event))
+          {
+            ClutterSeat *seat;
+
+            seat = clutter_backend_get_default_seat (context->backend);
+            clutter_seat_handle_device_event (seat, event);
+          }
+        break;
+
       case CLUTTER_EVENT_LAST:
         break;
     }
diff --git a/clutter/clutter/clutter-seat.c b/clutter/clutter/clutter-seat.c
index 73672bd361..ba9f2f55aa 100644
--- a/clutter/clutter/clutter-seat.c
+++ b/clutter/clutter/clutter-seat.c
@@ -674,6 +674,46 @@ clutter_seat_compress_motion (ClutterSeat        *seat,
     seat_class->compress_motion (seat, event, to_discard);
 }
 
+gboolean
+clutter_seat_handle_device_event (ClutterSeat  *seat,
+                                  ClutterEvent *event)
+{
+  ClutterSeatClass *seat_class;
+  ClutterInputDevice *device;
+
+  g_return_val_if_fail (CLUTTER_IS_SEAT (seat), FALSE);
+  g_return_val_if_fail (event, FALSE);
+
+  g_assert (event->type == CLUTTER_DEVICE_ADDED ||
+            event->type == CLUTTER_DEVICE_REMOVED);
+
+  seat_class = CLUTTER_SEAT_GET_CLASS (seat);
+
+  if (seat_class->handle_device_event)
+    {
+      if (!seat_class->handle_device_event (seat, event))
+        return FALSE;
+    }
+
+  device = clutter_event_get_source_device (event);
+  g_assert_true (CLUTTER_IS_INPUT_DEVICE (device));
+
+  switch (event->type)
+    {
+      case CLUTTER_DEVICE_ADDED:
+        g_signal_emit (seat, signals[DEVICE_ADDED], 0, device);
+        break;
+      case CLUTTER_DEVICE_REMOVED:
+        g_signal_emit (seat, signals[DEVICE_REMOVED], 0, device);
+        g_object_run_dispose (G_OBJECT (device));
+        break;
+      default:
+        break;
+    }
+
+  return TRUE;
+}
+
 void
 clutter_seat_warp_pointer (ClutterSeat *seat,
                            int          x,
diff --git a/clutter/clutter/clutter-seat.h b/clutter/clutter/clutter-seat.h
index 7818647af5..aa88d73003 100644
--- a/clutter/clutter/clutter-seat.h
+++ b/clutter/clutter/clutter-seat.h
@@ -106,6 +106,9 @@ struct _ClutterSeatClass
                             ClutterEvent       *event,
                             const ClutterEvent *to_discard);
 
+  gboolean (* handle_device_event) (ClutterSeat  *seat,
+                                    ClutterEvent *event);
+
   void (* warp_pointer) (ClutterSeat *seat,
                          int          x,
                          int          y);
@@ -181,6 +184,9 @@ void clutter_seat_compress_motion (ClutterSeat        *seat,
                                    ClutterEvent       *event,
                                    const ClutterEvent *to_discard);
 
+gboolean clutter_seat_handle_device_event (ClutterSeat  *seat,
+                                           ClutterEvent *event);
+
 CLUTTER_EXPORT
 void clutter_seat_warp_pointer (ClutterSeat *seat,
                                 int          x,