From 1c57f38daf4d7ef7986b951d2f70fc7ce1352289 Mon Sep 17 00:00:00 2001
From: Carlos Garnacho <carlosg@gnome.org>
Date: Mon, 15 Jul 2024 22:50:58 +0200
Subject: [PATCH] wayland: Only cancel touch when a new event handler takes
 over

And notably, don't cancel touch when an event handler is being
removed. Touch events are largely unaffected by most Wayland
grabs (pointer constraints, popups), so we might be cancelling
input too early if one of these wayland grabs was effective when
touch interaction began, but stopped sometime between touch updates.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3889>
(cherry picked from commit 77b21ef8dc820f6ccb80f8d1026d901872d6d780)
---
 src/wayland/meta-wayland-input.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/src/wayland/meta-wayland-input.c b/src/wayland/meta-wayland-input.c
index 44490ee19..f8829ea65 100644
--- a/src/wayland/meta-wayland-input.c
+++ b/src/wayland/meta-wayland-input.c
@@ -48,6 +48,12 @@ struct _MetaWaylandInput
   ClutterGrab *grab;
 };
 
+typedef enum
+{
+  INVALIDATE_FOCUS_FLAG_DEFAULT = 0,
+  INVALIDATE_FOCUS_FLAG_CANCEL_TOUCH = 1 << 0,
+} InvalidateFocusFlag;
+
 static void meta_wayland_input_sync_focus (MetaWaylandInput *input);
 
 G_DEFINE_FINAL_TYPE (MetaWaylandInput, meta_wayland_input, G_TYPE_OBJECT)
@@ -137,7 +143,8 @@ meta_wayland_event_handler_invalidate_focus (MetaWaylandEventHandler *handler,
 }
 
 static void
-meta_wayland_input_invalidate_all_focus (MetaWaylandInput *input)
+meta_wayland_input_invalidate_all_focus (MetaWaylandInput    *input,
+                                         InvalidateFocusFlag  flags)
 {
   MetaWaylandEventHandler *handler;
   MetaWaylandSeat *seat = input->seat;
@@ -161,7 +168,8 @@ meta_wayland_input_invalidate_all_focus (MetaWaylandInput *input)
       meta_wayland_event_handler_invalidate_focus (handler, device, NULL);
     }
 
-  if (meta_wayland_seat_has_touch (seat))
+  if (meta_wayland_seat_has_touch (seat) &&
+      (flags & INVALIDATE_FOCUS_FLAG_CANCEL_TOUCH) != 0)
     meta_wayland_touch_cancel (seat->touch);
 
   g_hash_table_iter_init (&iter, seat->tablet_seat->tablets);
@@ -257,7 +265,8 @@ meta_wayland_input_sync_focus (MetaWaylandInput *input)
 
   g_assert (!wl_list_empty (&input->event_handler_list));
   handler = wl_container_of (input->event_handler_list.next, handler, link);
-  meta_wayland_input_invalidate_all_focus (input);
+  meta_wayland_input_invalidate_all_focus (input,
+                                           INVALIDATE_FOCUS_FLAG_CANCEL_TOUCH);
 }
 
 static void
@@ -310,7 +319,8 @@ meta_wayland_input_attach_event_handler (MetaWaylandInput                *input,
                                 input);
     }
 
-  meta_wayland_input_invalidate_all_focus (input);
+  meta_wayland_input_invalidate_all_focus (input,
+                                           INVALIDATE_FOCUS_FLAG_DEFAULT);
 
   return handler;
 }
@@ -337,7 +347,8 @@ meta_wayland_input_detach_event_handler (MetaWaylandInput        *input,
   wl_list_remove (&handler->link);
 
   if (handler_change && !wl_list_empty (&input->event_handler_list))
-    meta_wayland_input_invalidate_all_focus (input);
+    meta_wayland_input_invalidate_all_focus (input,
+                                             INVALIDATE_FOCUS_FLAG_DEFAULT);
 
   if (input->grab && !should_be_grabbed (input))
     {