[gtk+/gtk-3-10] Fix font size when gdk_x11_display_set_window_scale() is used

[Matthias Clasen <matthiasc src gnome org>]

commit f27ad4df43a20a46ba805c72d145d6cf9bd1a466
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Wed Mar 5 15:42:38 2014 -0500

    Fix font size when gdk_x11_display_set_window_scale() is used
    
    We have a hack in the XSETTINGS code to substitute gtk-xft-dpi
    with gdk-unscaled-dpi unless the screen has a fixed window scale,
    in which case we just use gtk-xft-dpi.
    
    But if the screen is changed to have a fixed window scale, then
    the substituted value of gdk-unscaled-dpi will stick around until
    the next (coincidental) change to XSETTINGS. To fix this, force
    an immediate reread of the XSETTINGS property when
    gdk_x11_display_set_window_scale() is used.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=725754

 gdk/x11/gdkdisplay-x11.c   |   14 +++++++++++++-
 gdk/x11/xsettings-client.c |    6 ++++++
 gdk/x11/xsettings-client.h |    1 +
 3 files changed, 20 insertions(+), 1 deletions(-)
---
diff --git a/gdk/x11/gdkdisplay-x11.c b/gdk/x11/gdkdisplay-x11.c
index fbbd918..ae47812 100644
--- a/gdk/x11/gdkdisplay-x11.c
+++ b/gdk/x11/gdkdisplay-x11.c
@@ -2718,6 +2718,7 @@ gdk_x11_display_set_window_scale (GdkDisplay *display,
                                   gint scale)
 {
   GdkX11Screen *x11_screen;
+  gboolean need_reread_settings = FALSE;
 
   g_return_if_fail (GDK_IS_X11_DISPLAY (display));
 
@@ -2730,8 +2731,19 @@ gdk_x11_display_set_window_scale (GdkDisplay *display,
 
   x11_screen = GDK_X11_SCREEN (GDK_X11_DISPLAY (display)->screen);
 
-  x11_screen->fixed_window_scale = TRUE;
+  if (!x11_screen->fixed_window_scale)
+    {
+      x11_screen->fixed_window_scale = TRUE;
+
+      /* We treat screens with a window scale set differently when
+       * reading xsettings, so we need to reread */
+      need_reread_settings = TRUE;
+    }
+
   _gdk_x11_screen_set_window_scale (x11_screen, scale);
+
+  if (need_reread_settings)
+    _gdk_x11_settings_force_reread (x11_screen);
 }
 
 
diff --git a/gdk/x11/xsettings-client.c b/gdk/x11/xsettings-client.c
index 2d1c251..f5754d9 100644
--- a/gdk/x11/xsettings-client.c
+++ b/gdk/x11/xsettings-client.c
@@ -581,6 +581,12 @@ _gdk_x11_xsettings_init (GdkX11Screen *x11_screen)
 }
 
 void
+_gdk_x11_settings_force_reread (GdkX11Screen *x11_screen)
+{
+  read_settings (x11_screen, TRUE);
+}
+
+void
 _gdk_x11_xsettings_finish (GdkX11Screen *x11_screen)
 {
   gdk_window_remove_filter (gdk_screen_get_root_window (GDK_SCREEN (x11_screen)), 
gdk_xsettings_root_window_filter, x11_screen);
diff --git a/gdk/x11/xsettings-client.h b/gdk/x11/xsettings-client.h
index 9ae149e..89adc7d 100644
--- a/gdk/x11/xsettings-client.h
+++ b/gdk/x11/xsettings-client.h
@@ -27,5 +27,6 @@
 
 void _gdk_x11_xsettings_init            (GdkX11Screen        *x11_screen);
 void _gdk_x11_xsettings_finish          (GdkX11Screen        *x11_screen);
+void _gdk_x11_settings_force_reread     (GdkX11Screen        *x11_screen);
 
 #endif /* XSETTINGS_CLIENT_H */