[mutter] window: Throttle window move grab updates

[Marge Bot <marge-bot src gnome org>]

commit bd6b14a843563d6fb9cc6fdd37d6421d0e3b542a
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Oct 5 14:56:21 2022 +0200

    window: Throttle window move grab updates
    
    There is no point in moving a window at the input event refresh rate,
    when the end result will only be used once per update, thus, throttle
    the move done during grabs to once per stage update.
    
    Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2233
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2652>

 src/core/window.c | 47 ++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 42 insertions(+), 5 deletions(-)
---
diff --git a/src/core/window.c b/src/core/window.c
index 9666617b4c..d376017166 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -132,10 +132,6 @@ static void     ensure_mru_position_after (MetaWindow *window,
 static void meta_window_unqueue (MetaWindow    *window,
                                  MetaQueueType  queuebits);
 
-static void     update_move           (MetaWindow              *window,
-                                       MetaEdgeResistanceFlags  flags,
-                                       int                      x,
-                                       int                      y);
 static gboolean should_be_on_all_workspaces (MetaWindow *window);
 
 static void meta_window_flush_calc_showing   (MetaWindow *window);
@@ -5830,6 +5826,8 @@ update_move (MetaWindow              *window,
   display->grab_latest_motion_x = x;
   display->grab_latest_motion_y = y;
 
+  meta_display_clear_grab_move_resize_later (display);
+
   dx = x - display->grab_anchor_root_x;
   dy = y - display->grab_anchor_root_y;
 
@@ -5999,6 +5997,45 @@ update_move (MetaWindow              *window,
   meta_window_move_frame (window, TRUE, new_x, new_y);
 }
 
+static gboolean
+update_move_cb (gpointer user_data)
+{
+  MetaWindow *window = user_data;
+
+  window->display->grab_move_resize_later_id = 0;
+
+  update_move (window,
+               window->display->grab_last_edge_resistance_flags,
+               window->display->grab_latest_motion_x,
+               window->display->grab_latest_motion_y);
+
+  return G_SOURCE_REMOVE;
+}
+
+static void
+queue_update_move (MetaWindow              *window,
+                   MetaEdgeResistanceFlags  flags,
+                   int                      x,
+                   int                      y)
+{
+  MetaCompositor *compositor;
+  MetaLaters *laters;
+
+  window->display->grab_latest_motion_x = x;
+  window->display->grab_latest_motion_y = y;
+
+  if (window->display->grab_move_resize_later_id)
+    return;
+
+  compositor = meta_display_get_compositor (window->display);
+  laters = meta_compositor_get_laters (compositor);
+  window->display->grab_move_resize_later_id =
+    meta_laters_add (laters,
+                     META_LATER_BEFORE_REDRAW,
+                     update_move_cb,
+                     window, NULL);
+}
+
 static void
 update_resize (MetaWindow              *window,
                MetaEdgeResistanceFlags  flags,
@@ -6288,7 +6325,7 @@ meta_window_handle_mouse_grab_op_event  (MetaWindow         *window,
       meta_display_check_threshold_reached (window->display, x, y);
       if (meta_grab_op_is_moving (window->display->grab_op))
         {
-          update_move (window, flags, x, y);
+          queue_update_move (window, flags, x, y);
         }
       else if (meta_grab_op_is_resizing (window->display->grab_op))
         {