[mutter/gnome-3-22] wayland/pointer: Add way to cancel current grab

[Jonas Ådahl <jadahl src gnome org>]

commit 20efdfcb41e096586505bd9c2494d8780a5fdafe
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Sep 21 14:33:47 2016 +0800

    wayland/pointer: Add way to cancel current grab
    
    Previously a grab could suddenly end without the grabber knowing
    anything about it. Some grabs assume they won't suddenly end without
    notice, and can use then new 'cancel' vfunc to be notified.
    
    Currently a grab is cancelled when a new one is started (i.e. in
    meta_wayland_pointer_grab_start()), when a non-popup compositor wide
    event route is initiated, and when the seat looses the pointer
    capability.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=771858

 src/wayland/meta-wayland-pointer.c |   15 +++++++++++++++
 src/wayland/meta-wayland-pointer.h |    1 +
 2 files changed, 16 insertions(+), 0 deletions(-)
---
diff --git a/src/wayland/meta-wayland-pointer.c b/src/wayland/meta-wayland-pointer.c
index 55fcb06..7122d09 100644
--- a/src/wayland/meta-wayland-pointer.c
+++ b/src/wayland/meta-wayland-pointer.c
@@ -89,6 +89,9 @@ G_DEFINE_TYPE (MetaWaylandPointer, meta_wayland_pointer,
 static void
 meta_wayland_pointer_reset_grab (MetaWaylandPointer *pointer);
 
+static void
+meta_wayland_pointer_cancel_grab (MetaWaylandPointer *pointer);
+
 static MetaWaylandPointerClient *
 meta_wayland_pointer_client_new (void)
 {
@@ -226,6 +229,8 @@ sync_focus_surface (MetaWaylandPointer *pointer)
     case META_EVENT_ROUTE_COMPOSITOR_GRAB:
     case META_EVENT_ROUTE_FRAME_BUTTON:
       /* The compositor has a grab, so remove our focus... */
+      meta_wayland_pointer_cancel_grab (pointer);
+      meta_wayland_pointer_reset_grab (pointer);
       meta_wayland_pointer_set_focus (pointer, NULL);
       break;
 
@@ -498,6 +503,7 @@ meta_wayland_pointer_disable (MetaWaylandPointer *pointer)
                                    pointer->cursor_surface_destroy_id);
     }
 
+  meta_wayland_pointer_cancel_grab (pointer);
   meta_wayland_pointer_reset_grab (pointer);
   meta_wayland_pointer_set_focus (pointer, NULL);
 
@@ -862,6 +868,8 @@ meta_wayland_pointer_start_grab (MetaWaylandPointer *pointer,
 {
   const MetaWaylandPointerGrabInterface *interface;
 
+  meta_wayland_pointer_cancel_grab (pointer);
+
   pointer->grab = grab;
   interface = pointer->grab->interface;
   grab->pointer = pointer;
@@ -887,6 +895,13 @@ meta_wayland_pointer_end_grab (MetaWaylandPointer *pointer)
   meta_wayland_pointer_update_cursor_surface (pointer);
 }
 
+static void
+meta_wayland_pointer_cancel_grab (MetaWaylandPointer *pointer)
+{
+  if (pointer->grab->interface->cancel)
+    pointer->grab->interface->cancel (pointer->grab);
+}
+
 void
 meta_wayland_pointer_end_popup_grab (MetaWaylandPointer *pointer)
 {
diff --git a/src/wayland/meta-wayland-pointer.h b/src/wayland/meta-wayland-pointer.h
index 1076592..547cd56 100644
--- a/src/wayland/meta-wayland-pointer.h
+++ b/src/wayland/meta-wayland-pointer.h
@@ -46,6 +46,7 @@ struct _MetaWaylandPointerGrabInterface
                  const ClutterEvent     *event);
   void (*button) (MetaWaylandPointerGrab *grab,
                  const ClutterEvent     *event);
+  void (*cancel) (MetaWaylandPointerGrab *grab);
 };
 
 struct _MetaWaylandPointerGrab