[mistelix] Save Preferences only when they are dirty

[Jordi Mas <jmas src gnome org>]

commit 2a25cf93f976208b45008935db2e2c9682fd7279
Author: Jordi Mas <jmas softcatala org>
Date:   Tue Feb 9 19:45:38 2010 +0100

    Save Preferences only when they are dirty

 src/Core/Preferences.cs |   26 +++++++++++++++++++++++---
 1 files changed, 23 insertions(+), 3 deletions(-)
---
diff --git a/src/Core/Preferences.cs b/src/Core/Preferences.cs
index b1769bf..27bd40a 100644
--- a/src/Core/Preferences.cs
+++ b/src/Core/Preferences.cs
@@ -1,5 +1,5 @@
 //
-// Copyright (C) 2009 Jordi Mas i Hernandez, jmas softcatala org
+// Copyright (C) 2009-2010 Jordi Mas i Hernandez, jmas softcatala org
 //
 // Permission is hereby granted, free of charge, to any person obtaining
 // a copy of this software and associated documentation files (the
@@ -135,17 +135,22 @@ namespace Mistelix.Core
 			Load ();
 		}
 
+		public bool IsDirty { get; set;}
+
 		public void Save ()
 		{
 			try {
+				if (IsDirty == false)
+					return;
+
 				if (!Directory.Exists (config_path))
 					Directory.CreateDirectory (config_path);
 
 				XmlTextWriter writer = new XmlTextWriter (file, Encoding.UTF8);
 				writer.Formatting = Formatting.Indented;
-
 				properties.WriteXml (writer);
 				writer.Close ();
+				IsDirty = false;
 			}		
 			catch (Exception e)
 			{
@@ -170,17 +175,29 @@ namespace Mistelix.Core
 
 		public void SetIntValue (string key, int value)
 		{
+			if (properties[key] == value.ToString ())
+				return;
+
 			properties[key] = value.ToString ();
+			IsDirty = true;
 		}
 
 		public void SetBoolValue (string key, bool value)
 		{
+			if (properties [key] == value.ToString ())
+				return;
+
 			properties [key] = value.ToString ();
+			IsDirty = true;
 		}
 
 		public void SetStringValue (string key, string value)
 		{
+			if (properties[key] == value)
+				return;
+
 			properties[key] = value;
+			IsDirty = true;
 		}
 
 		void LoadDefaultValues ()
@@ -220,12 +237,15 @@ namespace Mistelix.Core
 			try {
 				LoadDefaultValues ();
 
-				if (File.Exists (file) == false)
+				if (File.Exists (file) == false) {
+					IsDirty = true;
 					return;
+				}
 
 				XmlTextReader reader = new XmlTextReader (file);
 				properties.ReadXml (reader);
 				reader.Close ();
+				IsDirty = false;
 			}
 			catch (Exception e)
 			{