From bd6b14a843563d6fb9cc6fdd37d6421d0e3b542a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonas=20=C3=85dahl?= <jadahl@gmail.com>
Date: Wed, 5 Oct 2022 14:56:21 +0200
Subject: [PATCH] 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 9666617b4..d37601716 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))
         {