[gtk/wip/chergert/for-main: 7/9] macos: send stop event when fingers touch

[Christian Hergert <chergert src gnome org>]

commit f0384ba0097c76f5b8158d8c34d7a238dfc95c2a
Author: Christian Hergert <christian hergert me>
Date:   Sat Feb 26 13:31:18 2022 -0800

    macos: send stop event when fingers touch
    
    When the fingers are placed on the touchpad, we get a scroll event with
    the phase NSEventPhaseMayBegin. We can use this to synthesize an is_stop
    event. This results in the scrolledwindow stopping scroll with stop
    gestures.
    
    This can cause another warning as well, however, which should be addressed
    from #4730.
    
    Fixes #4733

 gdk/macos/gdkmacosdisplay-translate.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
---
diff --git a/gdk/macos/gdkmacosdisplay-translate.c b/gdk/macos/gdkmacosdisplay-translate.c
index db1cfa2527..e261b8a4ae 100644
--- a/gdk/macos/gdkmacosdisplay-translate.c
+++ b/gdk/macos/gdkmacosdisplay-translate.c
@@ -635,6 +635,20 @@ fill_scroll_event (GdkMacosDisplay *self,
   state = _gdk_macos_display_get_current_mouse_modifiers (self) |
           _gdk_macos_display_get_current_keyboard_modifiers (self);
 
+  /* If we are starting a new phase, send a stop so any previous
+   * scrolling immediately stops.
+   */
+  if (phase == NSEventPhaseMayBegin)
+    {
+      ret = gdk_scroll_event_new (GDK_SURFACE (surface),
+                                  pointer,
+                                  NULL,
+                                  get_time_from_ns_event (nsevent),
+                                  state,
+                                  0.0, 0.0, TRUE);
+      _gdk_event_queue_append (GDK_DISPLAY (self), g_steal_pointer (&ret));
+    }
+
   dx = [nsevent deltaX];
   dy = [nsevent deltaY];