[gtk/wip/chergert/quartz4u] macos: discover NSWindow if one was not provided

[Christian Hergert <chergert src gnome org>]

commit 70ff231ea62735f0be1bfa4f074f5ff6ca48c0c6
Author: Christian Hergert <chergert redhat com>
Date:   Sat May 9 12:03:44 2020 -0700

    macos: discover NSWindow if one was not provided

 gdk/macos/gdkmacosdisplay-private.h   |  3 +++
 gdk/macos/gdkmacosdisplay-translate.c | 18 ++++++++++++----
 gdk/macos/gdkmacosdisplay.c           | 40 +++++++++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+), 4 deletions(-)
---
diff --git a/gdk/macos/gdkmacosdisplay-private.h b/gdk/macos/gdkmacosdisplay-private.h
index 6d31144415..01c20ccfe2 100644
--- a/gdk/macos/gdkmacosdisplay-private.h
+++ b/gdk/macos/gdkmacosdisplay-private.h
@@ -64,6 +64,9 @@ void             _gdk_macos_display_remove_frame_callback          (GdkMacosDisp
                                                                     GdkMacosSurface *surface);
 void             _gdk_macos_display_synthesize_motion              (GdkMacosDisplay *self,
                                                                     GdkMacosSurface *surface);
+NSWindow        *_gdk_macos_display_find_native_under_pointer      (GdkMacosDisplay *self,
+                                                                    int             *x,
+                                                                    int             *y);
 
 G_END_DECLS
 
diff --git a/gdk/macos/gdkmacosdisplay-translate.c b/gdk/macos/gdkmacosdisplay-translate.c
index a1e107ef03..1ab1fdbeec 100644
--- a/gdk/macos/gdkmacosdisplay-translate.c
+++ b/gdk/macos/gdkmacosdisplay-translate.c
@@ -711,7 +711,20 @@ _gdk_macos_display_translate (GdkMacosDisplay *self,
 
   /* Make sure the event has a window */
   if (!(nswindow = [nsevent window]))
-    return NULL;
+    {
+      int x_tmp;
+      int y_tmp;
+
+      if (!(nswindow = _gdk_macos_display_find_native_under_pointer (self, &x_tmp, &y_tmp)))
+        return NULL;
+
+      point.x = x_tmp;
+      point.y = y_tmp;
+    }
+  else
+    {
+      point = [[nswindow contentView] convertPoint:[nsevent locationInWindow] fromView:nil];
+    }
 
   /* Ignore unless it is for a GdkMacosWindow */
   if (!GDK_IS_MACOS_WINDOW (nswindow))
@@ -739,9 +752,6 @@ _gdk_macos_display_translate (GdkMacosDisplay *self,
   if (!(surface = [window getGdkSurface]))
     return NULL;
 
-  /* Get the location of event within toplevel coordinates */
-  point = [[window contentView] convertPoint:[nsevent locationInWindow] fromView:nil];
-
   /* Quartz handles resizing on its own, so stay out of the way. */
   if (test_resize (nsevent, surface, point.x, point.y))
     return NULL;
diff --git a/gdk/macos/gdkmacosdisplay.c b/gdk/macos/gdkmacosdisplay.c
index bc60017710..8646cca36b 100644
--- a/gdk/macos/gdkmacosdisplay.c
+++ b/gdk/macos/gdkmacosdisplay.c
@@ -799,3 +799,43 @@ _gdk_macos_display_remove_frame_callback (GdkMacosDisplay *self,
   if (self->awaiting_frames.length == 0)
     gdk_display_link_source_pause ((GdkDisplayLinkSource *)self->frame_source);
 }
+
+NSWindow *
+_gdk_macos_display_find_native_under_pointer (GdkMacosDisplay *self,
+                                              int             *x,
+                                              int             *y)
+{
+  NSPoint point;
+  int x_tmp;
+  int y_tmp;
+
+  g_assert (GDK_IS_MACOS_DISPLAY (self));
+
+  point = [NSEvent mouseLocation];
+
+  _gdk_macos_display_from_display_coords (self, point.x, point.y, &x_tmp, &y_tmp);
+
+  for (const GList *iter = self->surfaces.head; iter; iter = iter->next)
+    {
+      GdkSurface *surface = iter->data;
+
+      g_assert (GDK_IS_MACOS_SURFACE (surface));
+
+      if (x_tmp >= surface->x &&
+          x_tmp < surface->x + surface->width &&
+          y_tmp >= surface->y &&
+          y_tmp < surface->y + surface->height)
+        {
+          *x = x_tmp - surface->x;
+          *y = y_tmp - surface->y;
+
+          return _gdk_macos_surface_get_native (GDK_MACOS_SURFACE (surface));
+        }
+    }
+
+  *x = 0;
+  *y = 0;
+
+  return NULL;
+}
+