[gtk] quartz: do not cache the screen in the gdkmonitor

[Ignacio Casal Quinteiro <icq src gnome org>]

commit 1729da8a3e611ce83624663b1cf762080a13eab2
Author: Ignacio Casal Quinteiro <qignacio amazon com>
Date:   Sun Oct 7 21:51:35 2018 +0200

    quartz: do not cache the screen in the gdkmonitor
    
    Instead we just cache the monitor number and get
    out of it the nsscreen when it is needed. This is
    a requirement since it nsscreen it is not supposed
    to be cached.
    
    Fixes: https://gitlab.gnome.org/GNOME/gtk/issues/1312

 gdk/quartz/gdkmonitor-quartz.c | 17 ++++++++++++-----
 gdk/quartz/gdkmonitor-quartz.h |  2 +-
 gdk/quartz/gdkscreen-quartz.c  |  2 +-
 3 files changed, 14 insertions(+), 7 deletions(-)
---
diff --git a/gdk/quartz/gdkmonitor-quartz.c b/gdk/quartz/gdkmonitor-quartz.c
index 8130f2f6cc..b3e11f7d3e 100644
--- a/gdk/quartz/gdkmonitor-quartz.c
+++ b/gdk/quartz/gdkmonitor-quartz.c
@@ -35,12 +35,19 @@ gdk_quartz_monitor_get_workarea (GdkMonitor   *monitor,
 
   GDK_QUARTZ_ALLOC_POOL;
 
-  NSRect rect = [quartz_monitor->nsscreen visibleFrame];
+  NSArray *array = [NSScreen screens];
+  if (quartz_monitor->monitor_num < [array count])
+    {
+      NSScreen *screen = [array objectAtIndex:quartz_monitor->monitor_num];
+      NSRect rect = [screen visibleFrame];
 
-  dest->x = rect.origin.x - quartz_screen->min_x;
-  dest->y = quartz_screen->height - (rect.origin.y + rect.size.height) + quartz_screen->min_y;
-  dest->width = rect.size.width;
-  dest->height = rect.size.height;
+      dest->x = rect.origin.x - quartz_screen->min_x;
+      dest->y = quartz_screen->height - (rect.origin.y + rect.size.height) + quartz_screen->min_y;
+      dest->width = rect.size.width;
+      dest->height = rect.size.height;
+    }
+  else
+    *dest = monitor->geometry;
 
   GDK_QUARTZ_RELEASE_POOL;
 }
diff --git a/gdk/quartz/gdkmonitor-quartz.h b/gdk/quartz/gdkmonitor-quartz.h
index 448c483f7a..468a1d8f96 100644
--- a/gdk/quartz/gdkmonitor-quartz.h
+++ b/gdk/quartz/gdkmonitor-quartz.h
@@ -30,7 +30,7 @@ struct _GdkQuartzMonitor
 {
   GdkMonitor parent;
 
-  NSScreen *nsscreen;
+  gint monitor_num;
 };
 
 struct _GdkQuartzMonitorClass {
diff --git a/gdk/quartz/gdkscreen-quartz.c b/gdk/quartz/gdkscreen-quartz.c
index f8094354a0..303c603fcc 100644
--- a/gdk/quartz/gdkscreen-quartz.c
+++ b/gdk/quartz/gdkscreen-quartz.c
@@ -144,7 +144,7 @@ gdk_quartz_screen_calculate_layout (GdkQuartzScreen *screen)
                                                 "display", display,
                                                 NULL);
       g_ptr_array_add (display_quartz->monitors, monitor);
-      monitor->nsscreen = [array objectAtIndex:i];
+      monitor->monitor_num = i;
 
       NSRect rect = [[array objectAtIndex:i] frame];