[longomatch] Add a new base class for a canvas with a scaled background image

[Andoni Morales Alastruey <amorales src gnome org>]

commit 4255e88c75b3b230aa7a7c41754e1d20a966f276
Author: Andoni Morales Alastruey <ylatuya gmail com>
Date:   Tue Jun 17 18:51:04 2014 +0200

    Add a new base class for a canvas with a scaled background image

 LongoMatch.Drawing/Canvas.cs |   38 +++++++++++++++++++++++++++++++++++++-
 1 files changed, 37 insertions(+), 1 deletions(-)
---
diff --git a/LongoMatch.Drawing/Canvas.cs b/LongoMatch.Drawing/Canvas.cs
index f425c2d..8c91b1f 100644
--- a/LongoMatch.Drawing/Canvas.cs
+++ b/LongoMatch.Drawing/Canvas.cs
@@ -211,7 +211,43 @@ namespace LongoMatch.Drawing
                        }
                        lastTime = time;
                }
+       }
+       
+       public abstract class BackgroundCanvas: SelectionCanvas
+       {
+
+               Image background;
+
+               public BackgroundCanvas (IWidget widget): base (widget) {
+                       widget.SizeChangedEvent += HandleSizeChangedEvent;;
+               }
+
+               public Image Background {
+                       set {
+                               background = value;
+                               HandleSizeChangedEvent ();
+                       }
+                       get {
+                               return background;
+                       }
+               }
                
+               protected virtual void HandleSizeChangedEvent ()
+               {
+                       if (background != null) {
+                               background.ScaleFactor ((int) widget.Width, (int) widget.Height, out scaleX,
+                                                       out scaleY, out translation);
+                       }
+               }
+               
+               protected override void HandleDraw (object context, Area area)
+               {
+                       tk.Context = context;
+                       tk.Begin ();
+                       tk.TranslateAndScale (translation, new Point (scaleX, scaleY));
+                       tk.DrawImage (Background);
+                       tk.End ();
+                       base.HandleDraw (context, area);
+               }
        }
 }
-