[gnome-2048] Fix setting of grid size

[Juan R. Garcia Blanco <juanrgar src gnome org>]

commit c77e7edc681f735e17c0531af3efcb8fc7da1171
Author: Juan R. García Blanco <juanrgar gmail com>
Date:   Thu Feb 12 22:42:55 2015 +0100

    Fix setting of grid size
    
    Changing the grid size crashed the game. Now the background structure is
    only initialized when appropriate, i.e. when it has been cleared and
    when grid has the new settings applied.

 src/game.vala |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)
---
diff --git a/src/game.vala b/src/game.vala
index eedaf6f..6c6f5e0 100644
--- a/src/game.vala
+++ b/src/game.vala
@@ -128,6 +128,8 @@ public class Game : GLib.Object
     lines = contents.split ("\n");
     score = (uint)int.parse (lines[lines.length-2]);
 
+    if (_background != null)
+      _clear_background ();
     _init_background ();
     _restore_foreground ();
 
@@ -163,12 +165,13 @@ public class Game : GLib.Object
 
     if ((rows != _grid.rows) || (cols != _grid.cols)) {
       _clear_foreground ();
-      _clear_background ();
 
-      _init_background ();
+      _clear_background ();
 
       _grid = new Grid (rows, cols);
 
+      _init_background ();
+
       return true;
     }
 
@@ -223,6 +226,8 @@ public class Game : GLib.Object
         rect.actor.show ();
 
         _background[i,j] = rect;
+        _foreground_cur[i,j] = null;
+        _foreground_nxt[i,j] = null;
       }
     }
   }
@@ -507,6 +512,7 @@ public class Game : GLib.Object
           tile.actor.hide ();
           _view.remove_child (tile.actor);
           _foreground_cur[i,j] = null;
+          _foreground_nxt[i,j] = null;
         }
       }
     }