Add HiDPI support for lock screen (#148)

* Password dialog is now scaled
* Background of lock screen is now scaled

src/gs-lock-plug.c

@@ -980,6 +980,30 @@ set_face_image (GSLockPlug *plug)
 	return TRUE;
 }
 
+static void
+gs_lock_plug_get_preferred_width (GtkWidget *widget, gint *minimum_width, gint *natural_width)
+{
+    gint scale;
+
+    GTK_WIDGET_CLASS (gs_lock_plug_parent_class)->get_preferred_width (widget, minimum_width, natural_width);
+
+    scale = gtk_widget_get_scale_factor (widget);
+    *minimum_width /= scale;
+    *natural_width /= scale;
+}
+
+static void
+gs_lock_plug_get_preferred_height_for_width (GtkWidget *widget, gint width, gint *minimum_height, gint *natural_height)
+{
+    gint scale;
+
+    GTK_WIDGET_CLASS (gs_lock_plug_parent_class)->get_preferred_height_for_width (widget, width, minimum_height, natural_height);
+
+    scale = gtk_widget_get_scale_factor (widget);
+    *minimum_height /= scale;
+    *natural_height /= scale;
+}
+
 static void
 gs_lock_plug_show (GtkWidget *widget)
 {
@@ -1254,6 +1278,8 @@ gs_lock_plug_class_init (GSLockPlugClass *klass)
 	widget_class->style_set                      = gs_lock_plug_style_set;
 	widget_class->show                           = gs_lock_plug_show;
 	widget_class->hide                           = gs_lock_plug_hide;
+	widget_class->get_preferred_width            = gs_lock_plug_get_preferred_width;
+	widget_class->get_preferred_height_for_width = gs_lock_plug_get_preferred_height_for_width;
 
 	klass->close = gs_lock_plug_close;
 

src/gs-manager.c

@@ -1309,6 +1309,7 @@ apply_background_to_window (GSManager *manager,
 	GdkScreen       *screen;
 	int              width;
 	int              height;
+	gint             scale;
 
         mate_bg_load_from_preferences (manager->priv->bg);
 
@@ -1320,8 +1321,9 @@ apply_background_to_window (GSManager *manager,
 
 	display = gs_window_get_display (window);
 	screen = gdk_display_get_default_screen (display);
-	width = WidthOfScreen (gdk_x11_screen_get_xscreen (screen));
-	height = HeightOfScreen (gdk_x11_screen_get_xscreen (screen));
+	scale = gdk_window_get_scale_factor (gdk_screen_get_root_window (screen));
+	width = WidthOfScreen (gdk_x11_screen_get_xscreen (screen)) / scale;
+	height = HeightOfScreen (gdk_x11_screen_get_xscreen (screen)) / scale;
 	gs_debug ("Creating background w:%d h:%d", width, height);
 	surface = mate_bg_create_surface (manager->priv->bg,
 	                                  gs_window_get_gdk_window (window),