[gtk+] x11: Bring back fullscreen-on-all-monitors support

[Matthias Clasen <matthiasc src gnome org>]

commit 5c1d0915afd1e1e5a84523da7a9597f9ad68df99
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Apr 27 23:08:25 2016 -0400

    x11: Bring back fullscreen-on-all-monitors support
    
    It is unfortunate the EWMH requires Xinerama here - lets do this
    without the caching that was previously there, I don't think it is
    needed.

 gdk/x11/gdkscreen-x11.c |   45 +++++++++++++++++++++++++++++++++------------
 gdk/x11/gdkwindow-x11.c |   14 ++++++--------
 2 files changed, 39 insertions(+), 20 deletions(-)
---
diff --git a/gdk/x11/gdkscreen-x11.c b/gdk/x11/gdkscreen-x11.c
index 7dfe373..3e608bf 100644
--- a/gdk/x11/gdkscreen-x11.c
+++ b/gdk/x11/gdkscreen-x11.c
@@ -34,6 +34,10 @@
 
 #include <X11/Xatom.h>
 
+#ifdef HAVE_XFREE_XINERAMA
+#include <X11/extensions/Xinerama.h>
+#endif
+
 #ifdef HAVE_RANDR
 #include <X11/extensions/Xrandr.h>
 #endif
@@ -1071,35 +1075,52 @@ _gdk_x11_screen_get_edge_monitors (GdkScreen *screen,
   gint          bottom_most_pos = 0;
   gint          right_most_pos = 0;
   gint          i;
+#ifdef HAVE_XFREE_XINERAMA
+  XineramaScreenInfo *x_monitors;
+  int x_n_monitors;
+#endif
+
+  *top = *bottom = *left = *right = -1;
+
+#ifdef HAVE_XFREE_XINERAMA
+  if (!XineramaIsActive (x11_screen->xdisplay))
+    return;
 
-  for (i = 0; i < x11_screen->monitors->len; i++)
+  x_monitors = XineramaQueryScreens (x11_screen->xdisplay, &x_n_monitors);
+  if (x_n_monitors <= 0 || x_monitors == NULL)
     {
-      GdkMonitor *monitor = x11_screen->monitors->pdata[i];
-      GdkRectangle geometry;
+      if (x_monitors)
+        XFree (x_monitors);
 
-      gdk_monitor_get_geometry (monitor, &geometry);
+      return;
+    }
 
-      if (left && left_most_pos > geometry.x)
+  for (i = 0; i < x_n_monitors; i++)
+    {
+      if (left && left_most_pos > x_monitors[i].x_org)
        {
-         left_most_pos = geometry.x;
+         left_most_pos = x_monitors[i].x_org;
          *left = i;
        }
-      if (right && right_most_pos < geometry.x + geometry.width)
+      if (right && right_most_pos < x_monitors[i].x_org + x_monitors[i].width)
        {
-         right_most_pos = geometry.x + geometry.width;
+         right_most_pos = x_monitors[i].x_org + x_monitors[i].width;
          *right = i;
        }
-      if (top && top_most_pos > geometry.y)
+      if (top && top_most_pos > x_monitors[i].y_org)
        {
-         top_most_pos = geometry.y;
+         top_most_pos = x_monitors[i].y_org;
          *top = i;
        }
-      if (bottom && bottom_most_pos < geometry.y + geometry.height)
+      if (bottom && bottom_most_pos < x_monitors[i].y_org + x_monitors[i].height)
        {
-         bottom_most_pos = geometry.y + geometry.height;
+         bottom_most_pos = x_monitors[i].y_org + x_monitors[i].height;
          *bottom = i;
        }
     }
+
+  XFree (x_monitors);
+#endif
 }
 
 void
diff --git a/gdk/x11/gdkwindow-x11.c b/gdk/x11/gdkwindow-x11.c
index 3aa4038..fe311a7 100644
--- a/gdk/x11/gdkwindow-x11.c
+++ b/gdk/x11/gdkwindow-x11.c
@@ -4167,7 +4167,7 @@ gdk_x11_window_apply_fullscreen_mode (GdkWindow *window)
   if (GDK_WINDOW_IS_MAPPED (window))
     {
       XClientMessageEvent xclient;
-      gint                gdk_monitors[4];
+      gint                monitors[4];
       gint                i;
 
       memset (&xclient, 0, sizeof (xclient));
@@ -4208,16 +4208,14 @@ gdk_x11_window_apply_fullscreen_mode (GdkWindow *window)
        case GDK_FULLSCREEN_ON_ALL_MONITORS:
 
          _gdk_x11_screen_get_edge_monitors (GDK_WINDOW_SCREEN (window),
-                                            &gdk_monitors[0],
-                                            &gdk_monitors[1],
-                                            &gdk_monitors[2],
-                                            &gdk_monitors[3]);
+                                            &monitors[0],
+                                            &monitors[1],
+                                            &monitors[2],
+                                            &monitors[3]);
          /* Translate all 4 monitors from the GDK set into XINERAMA indices */
          for (i = 0; i < 4; ++i)
            {
-              /* FIXME
-               xclient.data.l[i] = _gdk_x11_screen_ge_xinerama_index (GDK_WINDOW_SCREEN (window), 
gdk_monitors[i]); */
-             xclient.data.l[i] = 0;
+             xclient.data.l[i] = monitors[i];
              /* Sanity check, if XINERAMA is not available, we could have invalid
               * negative values for the XINERAMA indices.
               */