[gtk+] GDK W32: Ensure that we use made-up monitors when there are none

[Руслан Ижбулатов <ruslanizhb src gnome org>]

commit 58ba4d6a3e0bda764ad7ae9aeede39627ec6deb1
Author: Руслан Ижбулатов <lrn1986 gmail com>
Date:   Fri Jan 20 10:23:00 2017 +0000

    GDK W32: Ensure that we use made-up monitors when there are none
    
    Previously GDK only made up monitors when it initially found none. Now it
    also makes up monitors when it initially finds some, but later fails to get
    their informatin in a normal way and finally prunes them out, being left with
    zero monitors.
    
    Having zero-length monitor array is unexpected and causes a number
    of critical warnings and some critical functionality (such as displaying
    drop-down menus) fails in such cases.
    
    Ideally, there might be such a way to interrogate W32 API that produces the
    information about non-real (but active) monitors out of it so that it isn't
    necessary for us to make stuff up. However, this code is already complicated,
    and i am not prepared to dig W32 API to find a way to do this.
    
    This fixes the issues people had when they accessed a Windows desktop via RDP.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=777527

 gdk/win32/gdkmonitor-win32.c |   37 +++++++++++++++++++++++++++++++------
 1 files changed, 31 insertions(+), 6 deletions(-)
---
diff --git a/gdk/win32/gdkmonitor-win32.c b/gdk/win32/gdkmonitor-win32.c
index 1686eb5..ea58cb5 100644
--- a/gdk/win32/gdkmonitor-win32.c
+++ b/gdk/win32/gdkmonitor-win32.c
@@ -722,6 +722,25 @@ enum_monitor (HMONITOR hmonitor,
   return TRUE;
 }
 
+static void
+prune_monitors (EnumMonitorData *data)
+{
+  gint i;
+
+  for (i = 0; i < data->monitors->len; i++)
+    {
+      GdkWin32Monitor *m;
+
+      m = g_ptr_array_index (data->monitors, i);
+
+      if (m->remove)
+        {
+          g_ptr_array_remove_index (data->monitors, i);
+          continue;
+        }
+    }
+}
+
 GPtrArray *
 _gdk_win32_display_get_monitor_list (GdkWin32Display *win32_display)
 {
@@ -743,6 +762,18 @@ _gdk_win32_display_get_monitor_list (GdkWin32Display *win32_display)
 
   EnumDisplayMonitors (NULL, NULL, enum_monitor, (LPARAM) &data);
 
+  prune_monitors (&data);
+
+  if (data.monitors->len == 0 && data.have_monitor_devices)
+    {
+      /* We thought we had monitors, but enumeration eventually failed, and
+       * we have none. Try again, this time making stuff up as we go.
+       */
+      data.have_monitor_devices = FALSE;
+      EnumDisplayMonitors (NULL, NULL, enum_monitor, (LPARAM) &data);
+      prune_monitors (&data);
+    }
+
   _gdk_offset_x = G_MININT;
   _gdk_offset_y = G_MININT;
 
@@ -753,12 +784,6 @@ _gdk_win32_display_get_monitor_list (GdkWin32Display *win32_display)
 
       m = g_ptr_array_index (data.monitors, i);
 
-      if (m->remove)
-        {
-          g_ptr_array_remove_index (data.monitors, i);
-          continue;
-        }
-
       /* Calculate offset */
       gdk_monitor_get_geometry (GDK_MONITOR (m), &rect);
       _gdk_offset_x = MAX (_gdk_offset_x, -rect.x);