[gtk/wip/chergert/quartz4u] macos: locate surface at pointer position

[Christian Hergert <chergert src gnome org>]

commit 6ce3c33793f7ff0bd6bc6cdaa21b0d2436664bdc
Author: Christian Hergert <chergert redhat com>
Date:   Mon May 4 12:16:46 2020 -0700

    macos: locate surface at pointer position

 gdk/macos/gdkmacosdevice.c | 39 ++++++++++++++++++++++++++++++++-------
 1 file changed, 32 insertions(+), 7 deletions(-)
---
diff --git a/gdk/macos/gdkmacosdevice.c b/gdk/macos/gdkmacosdevice.c
index 0f8e47c552..82c956e690 100644
--- a/gdk/macos/gdkmacosdevice.c
+++ b/gdk/macos/gdkmacosdevice.c
@@ -25,7 +25,8 @@
 
 #include "gdkmacoscursor-private.h"
 #include "gdkmacosdevice.h"
-#include "gdkmacossurface.h"
+#include "gdkmacosdisplay-private.h"
+#include "gdkmacossurface-private.h"
 
 struct _GdkMacosDevice
 {
@@ -59,21 +60,45 @@ gdk_macos_device_set_surface_cursor (GdkDevice  *device,
     }
 }
 
-static void
-gdk_macos_device_finalize (GObject *object)
+static GdkSurface *
+gdk_macos_device_surface_at_position (GdkDevice       *device,
+                                      gdouble         *win_x,
+                                      gdouble         *win_y,
+                                      GdkModifierType *state,
+                                      gboolean         get_toplevel)
 {
-  G_OBJECT_CLASS (gdk_macos_device_parent_class)->finalize (object);
+  GdkMacosDisplay *display;
+  GdkMacosSurface *surface;
+  NSPoint point;
+  gint x;
+  gint y;
+
+  g_assert (GDK_IS_MACOS_DEVICE (device));
+  g_assert (win_x != NULL);
+  g_assert (win_y != NULL);
+
+  point = [NSEvent mouseLocation];
+  display = GDK_MACOS_DISPLAY (gdk_device_get_display (device));
+
+  if (state != NULL)
+    *state = (_gdk_macos_display_get_current_keyboard_modifiers (display) |
+              _gdk_macos_display_get_current_mouse_modifiers (display));
+
+  surface = _gdk_macos_display_get_surface_at_display_coords (display, point.x, point.y, &x, &y);
+
+  *win_x = x;
+  *win_y = y;
+
+  return GDK_SURFACE (surface);
 }
 
 static void
 gdk_macos_device_class_init (GdkMacosDeviceClass *klass)
 {
-  GObjectClass *object_class = G_OBJECT_CLASS (klass);
   GdkDeviceClass *device_class = GDK_DEVICE_CLASS (klass);
 
-  object_class->finalize = gdk_macos_device_finalize;
-
   device_class->set_surface_cursor = gdk_macos_device_set_surface_cursor;
+  device_class->surface_at_position = gdk_macos_device_surface_at_position;
 }
 
 static void