[longomatch] Add support for exporting canvases with a roi defined

[Andoni Morales Alastruey <amorales src gnome org>]

commit 2f2d93d03f78f1ffe274c13f46bee17af214be4e
Author: Andoni Morales Alastruey <ylatuya gmail com>
Date:   Tue Apr 21 11:48:31 2015 +0200

    Add support for exporting canvases with a roi defined

 .../Interfaces/Drawing/IDrawingToolkit.cs          |    2 +-
 LongoMatch.Drawing.Cairo/CairoBackend.cs           |   15 +++++++++------
 LongoMatch.Drawing/Widgets/Blackboard.cs           |    8 +++++++-
 3 files changed, 17 insertions(+), 8 deletions(-)
---
diff --git a/LongoMatch.Core/Interfaces/Drawing/IDrawingToolkit.cs 
b/LongoMatch.Core/Interfaces/Drawing/IDrawingToolkit.cs
index 3214770..cb76f3a 100644
--- a/LongoMatch.Core/Interfaces/Drawing/IDrawingToolkit.cs
+++ b/LongoMatch.Core/Interfaces/Drawing/IDrawingToolkit.cs
@@ -105,7 +105,7 @@ namespace LongoMatch.Core.Interfaces.Drawing
 
                void DrawArrow (Point start, Point stop, int lenght, double degrees, bool closed);
 
-               void Save (ICanvas canvas, double width, double height, string filename);
+               void Save (ICanvas canvas, Area area, string filename);
 
                Image Copy (ICanvas canvas, double width, double height);
 
diff --git a/LongoMatch.Drawing.Cairo/CairoBackend.cs b/LongoMatch.Drawing.Cairo/CairoBackend.cs
index 68f7d70..1696b3f 100644
--- a/LongoMatch.Drawing.Cairo/CairoBackend.cs
+++ b/LongoMatch.Drawing.Cairo/CairoBackend.cs
@@ -190,9 +190,11 @@ namespace LongoMatch.Drawing.Cairo
 
                public void Clip (Area area)
                {
-                       CContext.Rectangle (area.Start.X, area.Start.Y,
-                               area.Width, area.Height);
-                       CContext.Clip ();
+                       if (!disableScalling) {
+                               CContext.Rectangle (area.Start.X, area.Start.Y,
+                                       area.Width, area.Height);
+                               CContext.Clip ();
+                       }
                }
 
                public Area UserToDevice (Area a)
@@ -490,12 +492,13 @@ namespace LongoMatch.Drawing.Cairo
                        return img;
                }
 
-               public void Save (ICanvas canvas, double width, double height, string filename)
+               public void Save (ICanvas canvas, Area area, string filename)
                {
-                       ImageSurface pngSurface = new ImageSurface (Format.ARGB32, (int)width, (int)height);
+                       ImageSurface pngSurface = new ImageSurface (Format.ARGB32, (int)area.Width, 
(int)area.Height);
                        disableScalling = true;
                        using (CairoContext c = new CairoContext (new global::Cairo.Context (pngSurface))) {
-                               canvas.Draw (c, new Area (new Point (0, 0), width, height));
+                               (c.Value as global::Cairo.Context).Translate (-area.Start.X, -area.Start.Y);
+                               canvas.Draw (c, null);
                        }
                        pngSurface.WriteToPng (filename);
                        disableScalling = false;
diff --git a/LongoMatch.Drawing/Widgets/Blackboard.cs b/LongoMatch.Drawing/Widgets/Blackboard.cs
index 8b4f35c..afb3b76 100644
--- a/LongoMatch.Drawing/Widgets/Blackboard.cs
+++ b/LongoMatch.Drawing/Widgets/Blackboard.cs
@@ -171,8 +171,14 @@ namespace LongoMatch.Drawing.Widgets
 
                public void Save (string filename)
                {
+                       Area area;
+
                        ClearSelection ();
-                       tk.Save (this, Background.Width, Background.Height, filename);
+                       area = RegionOfInterest;
+                       if (area == null) {
+                               area = new Area (0, 0, Background.Width, Background.Height); 
+                       }
+                       tk.Save (this, area, filename);
                }
 
                public void Zoom (double zoom, Point center = null)