xsettings: Don't mix GnomeRR and GDK information

If we don't mix information from GnomeRR and GDK, then the "changed"
signal on GnomeRRScreen is all we need to properly know when the
resolution of the system is changed - mixing them presents problems
because GDK may not yet have updated it's information from X when the
"changed" is triggered by a D-Bus signal.

We still use GDK information before we have a GnomeRRScreen to minimize
the chance of switching the window scale during startup.

https://bugzilla.gnome.org/show_bug.cgi?id=709859

1 files changed, 63 insertions, 16 deletions

diff --git a/plugins/xsettings/gsd-xsettings-manager.c b/plugins/xsettings/gsd-xsettings-manager.c
index 6d04b524..366a55b4 100644
--- a/plugins/xsettings/gsd-xsettings-manager.c
+++ b/plugins/xsettings/gsd-xsettings-manager.c
@@ -511,44 +511,91 @@ primary_monitor_should_skip_resolution_check (GnomeRROutput *primary)
         return FALSE;
 }
 
+static void
+get_dimensions_xrandr (GnomeRROutput *primary,
+                       int           *width,
+                       int           *height,
+                       int           *width_mm,
+                       int           *height_mm)
+{
+        GnomeRRMode *mode;
+
+        mode = gnome_rr_output_get_current_mode (primary);
+        *width = gnome_rr_mode_get_width (mode);
+        *height = gnome_rr_mode_get_height (mode);
+
+        gnome_rr_output_get_physical_size (primary,
+                                           width_mm,
+                                           height_mm);
+}
+
+static void
+get_dimensions_gdk (int *width,
+                    int *height,
+                    int *width_mm,
+                    int *height_mm)
+{
+        GdkDisplay *display;
+        GdkScreen *screen;
+        GdkRectangle rect;
+        int primary;
+        int monitor_scale;
+
+        display = gdk_display_get_default ();
+        screen = gdk_display_get_default_screen (display);
+        primary = gdk_screen_get_primary_monitor (screen);
+        gdk_screen_get_monitor_geometry (screen, primary, &rect);
+        monitor_scale = gdk_screen_get_monitor_scale_factor (screen, primary);
+
+        *width = rect.width * monitor_scale;
+        *height = rect.height * monitor_scale;
+
+        *width_mm = gdk_screen_get_monitor_width_mm (screen, primary);
+        *height_mm = gdk_screen_get_monitor_height_mm (screen, primary);
+}
+
 static int
 get_window_scale (GnomeXSettingsManager *manager)
 {
 	GSettings  *interface_settings;
         int window_scale;
-        GdkRectangle rect;
-        GdkDisplay *display;
-        GdkScreen *screen;
+        int width, height;
         int width_mm, height_mm;
-        int monitor_scale;
         double dpi_x, dpi_y;
 
 	interface_settings = g_hash_table_lookup (manager->priv->settings, INTERFACE_SETTINGS_SCHEMA);
         window_scale =
                 g_settings_get_uint (interface_settings, SCALING_FACTOR_KEY);
         if (window_scale == 0) {
-                int primary;
                 GnomeRROutput *output = NULL;
 
                 window_scale = 1;
 
                 if (manager->priv->rr_screen)
                         output = get_primary_output (manager->priv->rr_screen);
-                if (output && primary_monitor_should_skip_resolution_check (output))
-                        goto out;
 
-                display = gdk_display_get_default ();
-                screen = gdk_display_get_default_screen (display);
-                primary = gdk_screen_get_primary_monitor (screen);
-                gdk_screen_get_monitor_geometry (screen, primary, &rect);
-                width_mm = gdk_screen_get_monitor_width_mm (screen, primary);
-                height_mm = gdk_screen_get_monitor_height_mm (screen, primary);
-                monitor_scale = gdk_screen_get_monitor_scale_factor (screen, primary);
+                if (output) {
+                        if (primary_monitor_should_skip_resolution_check (output))
+                                goto out;
+
+                        get_dimensions_xrandr (output,
+                                               &width, &height,
+                                               &width_mm, &height_mm);
+                } else {
+                        /* Before the D-Bus DisplayConfig service exported by
+                         * Mutter becomes available, use the current information
+                         * that GDK has from the X server; in simple cases, this
+                         * will hopefully keep us from switching the window_scale
+                         * during startup.
+                         */
+                        get_dimensions_gdk (&width, &height,
+                                            &width_mm, &height_mm);
+                }
 
                 window_scale = 1;
                 if (width_mm > 0 && height_mm > 0) {
-                        dpi_x = (double)rect.width * monitor_scale / (width_mm / 25.4);
-                        dpi_y = (double)rect.height * monitor_scale / (height_mm / 25.4);
+                        dpi_x = (double)width / (width_mm / 25.4);
+                        dpi_y = (double)height / (height_mm / 25.4);
                         /* We don't completely trust these values so both
                            must be high, and never pick higher ratio than
                            2 automatically */