[mutter/wip/carlosg/grabs-pt1: 12/13] clutter: Integrate ClutterSeat grabs into ClutterGrab

[Carlos Garnacho <carlosg src gnome org>]

commit 9fb38b4ed8b074ee335cb128d97a7d44833e3bc5
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Oct 28 17:05:44 2021 +0200

    clutter: Integrate ClutterSeat grabs into ClutterGrab
    
    As ClutterGrab is a stack, the backend only cares about some grab
    existing currently or not. Make it sure that we grab whenever we
    go to >=1 grabs, and ungrab whenever we go to <1.

 clutter/clutter/clutter-stage.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
---
diff --git a/clutter/clutter/clutter-stage.c b/clutter/clutter/clutter-stage.c
index bbd57d905f..85ebec59d9 100644
--- a/clutter/clutter/clutter-stage.c
+++ b/clutter/clutter/clutter-stage.c
@@ -62,6 +62,7 @@
 #include "clutter-paint-volume-private.h"
 #include "clutter-pick-context-private.h"
 #include "clutter-private.h"
+#include "clutter-seat-private.h"
 #include "clutter-stage-manager-private.h"
 #include "clutter-stage-private.h"
 #include "clutter-stage-view-private.h"
@@ -3757,6 +3758,18 @@ clutter_stage_grab (ClutterStage *stage,
   g_return_val_if_fail (CLUTTER_IS_STAGE (stage), NULL);
   g_return_val_if_fail (CLUTTER_IS_ACTOR (actor), NULL);
 
+  if (!priv->grabs)
+    {
+      ClutterMainContext *context;
+      ClutterSeat *seat;
+
+      /* First grab in the chain, trigger a backend grab too */
+      context = _clutter_context_get_default ();
+      seat = clutter_backend_get_default_seat (context->backend);
+      if (!clutter_seat_grab (seat, clutter_get_current_event_time ()))
+        return NULL;
+    }
+
   grab = g_new0 (ClutterGrab, 1);
   grab->stage = stage;
   grab->actor = actor;
@@ -3801,6 +3814,17 @@ clutter_stage_unlink_grab (ClutterStage *stage,
 
   clutter_actor_detach_grab (grab->actor, grab);
 
+  if (!priv->grabs)
+    {
+      ClutterMainContext *context;
+      ClutterSeat *seat;
+
+      /* This was the last remaining grab, trigger a backend ungrab */
+      context = _clutter_context_get_default ();
+      seat = clutter_backend_get_default_seat (context->backend);
+      clutter_seat_ungrab (seat, clutter_get_current_event_time ());
+    }
+
   grab->next = NULL;
   grab->prev = NULL;
 }