[tasque/transition: 65/213] Transition to CollectionView and TreeModelListAdapter

[Antonius Riha <antoniusri src gnome org>]

commit 28da7c66c9baa0ae4bb37c236d4526f758e4da47
Author: Antonius Riha <antoniusriha gmail com>
Date:   Sun Jul 8 21:39:56 2012 +0200

    Transition to CollectionView and TreeModelListAdapter
    
    * IBackend.cs: SortedTasks is now IEnumerable, so it can be assigned from CollectionView.
    * ITask.cs:
    	- ITask needs to be an INotifyPropertyChanged for the CollectionView to work properly.
    	- There is no need for the CompareTo method anymore. This is already defined in IComparable<T>.
    * AbstractTask.cs: Provide a OnNotifyPropertyChanged method for children to call.
    * Application.cs:
    	- Hook up tooltip change handler with CollectionView's CollectionChanged event.
    	- Use CollectionView.Count to retrieve the number of items in the View.
    * DummyBackend.cs: Apply CollectionView for SortedTasks implementation. Use the default comparer (which is used by the default SortDescription).
    * DummyTask.cs: Fire OnPropertyChanged events instead of calling IBackend.UpdateTask (ITask).
    * CompletedTaskGroup.cs:
    	- Add static helper method for creating the completed tasks' CollectionView.
    	- Remove CompletedTasksComparer, which is obsolete since the introduction of CollectionView.
    * CompletedTaskGroupModel.cs:
    	- Adjust FilterTasks method to meet the requirements of CollectionView.Filter predicate.
    	- Adjust to changes of base class.
    * TaskGroup.cs:
    	- Adjust for the use of CollectionView
    	- Use TreeModelListAdapter<ITask> to hook up the underlying CollectionView with the TreeView.
    	- Use CollectionView.Refresh method to reflect changes in the filter.
    * TaskGroupModel.cs:
    	- Change base class from TreeModelFilter to CollectionView<ITask> and adjust resp. members appropriately
    	- Rearrange some members to better meet oo design concepts
    	- Shorten IsToday method.
    * TaskGroupModelFactory.cs: Adjust to new TaskGroupModel class.

 src/libtasque/IBackend.cs                 |    3 +-
 src/libtasque/ITask.cs                    |   15 +----
 src/tasque/AbstractTask.cs                |    9 +++
 src/tasque/Application.cs                 |   20 ++----
 src/tasque/Backends/Dummy/DummyBackend.cs |   17 +++--
 src/tasque/Backends/Dummy/DummyTask.cs    |   59 +++++++++-------
 src/tasque/CompletedTaskGroup.cs          |   35 +++++-----
 src/tasque/CompletedTaskGroupModel.cs     |   39 ++++++++---
 src/tasque/TaskGroup.cs                   |   43 +++++++++---
 src/tasque/TaskGroupModel.cs              |  107 +++++++++++++++++------------
 src/tasque/TaskGroupModelFactory.cs       |   37 ++++++++--
 11 files changed, 236 insertions(+), 148 deletions(-)
---
diff --git a/src/libtasque/IBackend.cs b/src/libtasque/IBackend.cs
index e41b885..8bfaf4a 100644
--- a/src/libtasque/IBackend.cs
+++ b/src/libtasque/IBackend.cs
@@ -4,6 +4,7 @@
 using System;
 using System.Collections.ObjectModel;
 using System.Collections.Generic;
+using System.Collections;
 
 namespace Tasque.Backends
 {
@@ -38,7 +39,7 @@ namespace Tasque.Backends
 			get;
 		}
 
-		IEnumerable<ITask> SortedTasks {
+		IEnumerable SortedTasks {
 			get;
 		}
 		
diff --git a/src/libtasque/ITask.cs b/src/libtasque/ITask.cs
index 852c263..18dba53 100644
--- a/src/libtasque/ITask.cs
+++ b/src/libtasque/ITask.cs
@@ -3,10 +3,11 @@
 
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 
 namespace Tasque
 {
-	public interface ITask : IComparable<ITask>
+	public interface ITask : IComparable<ITask>, INotifyPropertyChanged
 	{
 		#region Properties
 		/// <value>
@@ -144,18 +145,6 @@ namespace Tasque
 		void SaveNote (INote note);
 		
 		/// <summary>
-		/// This is used for sorting tasks in the TaskWindow and should compare
-		/// based on due date.
-		/// </summary>
-		/// <param name="task">
-		/// A <see cref="ITask"/>
-		/// </param>
-		/// <returns>
-		/// A <see cref="System.Int32"/>
-		/// </returns>
-		int CompareTo (ITask task);
-		
-		/// <summary>
 		/// This is the same as CompareTo above but should use completion date
 		/// instead of due date.  This is used to sort items in the
 		/// CompletedTaskGroup.
diff --git a/src/tasque/AbstractTask.cs b/src/tasque/AbstractTask.cs
index 3aa5a2d..32be7ef 100644
--- a/src/tasque/AbstractTask.cs
+++ b/src/tasque/AbstractTask.cs
@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 
 namespace Tasque
 {
@@ -150,6 +151,14 @@ namespace Tasque
 			return CompareByPriorityAndName (task);
 		}
 		#endregion // Methods
+
+		public event PropertyChangedEventHandler PropertyChanged;
+
+		protected void OnPropertyChanged (string propertyName)
+		{
+			if (PropertyChanged != null)
+				PropertyChanged (this, new PropertyChangedEventArgs (propertyName));
+		}
 		
 		#region Private Methods
 		
diff --git a/src/tasque/Application.cs b/src/tasque/Application.cs
index 652c560..fe570eb 100644
--- a/src/tasque/Application.cs
+++ b/src/tasque/Application.cs
@@ -453,13 +453,10 @@ namespace Tasque
 		{
 			foreach (TaskGroupModel model in new TaskGroupModel[] { overdue_tasks, today_tasks, tomorrow_tasks })
 			{
-				if (model == null) {
+				if (model == null)
 					continue;
-				}
 				
-				model.RowInserted -= OnTooltipModelChanged;
-				model.RowChanged -= OnTooltipModelChanged;
-				model.RowDeleted -= OnTooltipModelChanged;
+				model.CollectionChanged -= OnTooltipModelChanged;
 			}
 		}
 
@@ -484,13 +481,10 @@ namespace Tasque
 
 			foreach (TaskGroupModel model in new TaskGroupModel[] { overdue_tasks, today_tasks, tomorrow_tasks })
 			{
-				if (model == null) {
+				if (model == null)
 					continue;
-				}
 				
-				model.RowInserted += OnTooltipModelChanged;
-				model.RowChanged += OnTooltipModelChanged;
-				model.RowDeleted += OnTooltipModelChanged;
+				model.CollectionChanged += OnTooltipModelChanged;
 			}
 		}
 		
@@ -502,7 +496,7 @@ namespace Tasque
 
 			StringBuilder sb = new StringBuilder ();
 			if (overdue_tasks != null) {
-				int count =  overdue_tasks.IterNChildren ();
+				int count =  overdue_tasks.Count;
 
 				if (count > 0) {
 					sb.Append (String.Format (Catalog.GetPluralString ("{0} task is Overdue\n", "{0} tasks are Overdue\n", count), count));
@@ -510,7 +504,7 @@ namespace Tasque
 			}
 			
 			if (today_tasks != null) {
-				int count =  today_tasks.IterNChildren ();
+				int count =  today_tasks.Count;
 
 				if (count > 0) {
 					sb.Append (String.Format (Catalog.GetPluralString ("{0} task for Today\n", "{0} tasks for Today\n", count), count));
@@ -518,7 +512,7 @@ namespace Tasque
 			}
 
 			if (tomorrow_tasks != null) {
-				int count =  tomorrow_tasks.IterNChildren ();
+				int count =  tomorrow_tasks.Count;
 
 				if (count > 0) {
 					sb.Append (String.Format (Catalog.GetPluralString ("{0} task for Tomorrow\n", "{0} tasks for Tomorrow\n", count), count));
diff --git a/src/tasque/Backends/Dummy/DummyBackend.cs b/src/tasque/Backends/Dummy/DummyBackend.cs
index 49e0fbe..be9eb9d 100644
--- a/src/tasque/Backends/Dummy/DummyBackend.cs
+++ b/src/tasque/Backends/Dummy/DummyBackend.cs
@@ -2,11 +2,11 @@
 // User: boyd at 7:10 AMÂ2/11/2008
 
 using System;
-using System.Collections.Generic;
-using Mono.Unix;
 using Tasque.Backends;
 using System.Collections.ObjectModel;
-using System.Linq;
+using CollectionTransforms;
+using System.ComponentModel;
+using System.Collections;
 
 namespace Tasque.Backends.Dummy
 {
@@ -39,6 +39,13 @@ namespace Tasque.Backends.Dummy
 			initialized = false;
 			newTaskId = 0;
 			Tasks = new ObservableCollection<ITask> ();
+			var cv =  new CollectionView<ITask> (Tasks);
+			/*
+			 * this invokes the default comparer, which in turn
+			 * will use the IComparable implmentation of Task
+			 */
+			cv.SortDescriptions.Add (new SortDescription ());
+			SortedTasks = cv;
 			
 			categoryListStore = new Gtk.ListStore (typeof(ICategory));
 			
@@ -55,9 +62,7 @@ namespace Tasque.Backends.Dummy
 		/// <value>
 		/// All the tasks including ITaskDivider items.
 		/// </value>
-		public IEnumerable<ITask> SortedTasks {
-			get { return Tasks.OrderBy (t => t, Comparer<ITask>.Default); }
-		}
+		public IEnumerable SortedTasks { get; private set; }
 
 		public ObservableCollection<ITask> Tasks { get; private set; }
 		
diff --git a/src/tasque/Backends/Dummy/DummyTask.cs b/src/tasque/Backends/Dummy/DummyTask.cs
index e8e86e3..1033d83 100644
--- a/src/tasque/Backends/Dummy/DummyTask.cs
+++ b/src/tasque/Backends/Dummy/DummyTask.cs
@@ -47,13 +47,14 @@ namespace Tasque.Backends.Dummy
 		{
 			get { return name; }
 			set {
-Logger.Debug ("Setting new task name");
-				if (value == null)
-					name = string.Empty;
+				if (value != name) {
+					Logger.Debug ("Setting new task name");
+					if (value == null)
+						name = string.Empty;
 				
-				name = value.Trim ();
-				
-				backend.UpdateTask (this);
+					name = value.Trim ();
+					OnPropertyChanged ("Name");
+				}
 			}
 		}
 		
@@ -61,10 +62,11 @@ Logger.Debug ("Setting new task name");
 		{
 			get { return dueDate; }
 			set {
-Logger.Debug ("Setting new task due date");
-				dueDate = value;
-				
-				backend.UpdateTask (this);
+				if (value != dueDate) {
+					Logger.Debug ("Setting new task due date");
+					dueDate = value;
+					OnPropertyChanged ("DueDate");
+				}
 			}
 		}
 		
@@ -72,10 +74,11 @@ Logger.Debug ("Setting new task due date");
 		{
 			get { return completionDate; }
 			set {
-Logger.Debug ("Setting new task completion date");
-				completionDate = value;
-				
-				backend.UpdateTask (this);
+				if (value != completionDate) {
+					Logger.Debug ("Setting new task completion date");
+					completionDate = value;
+					OnPropertyChanged ("CompletionDate");
+				}
 			}
 		}
 		
@@ -88,10 +91,11 @@ Logger.Debug ("Setting new task completion date");
 		{
 			get { return priority; }
 			set {
-Logger.Debug ("Setting new task priority");
-				priority = value;
-				
-				backend.UpdateTask (this);
+				if (value != priority) {
+					Logger.Debug ("Setting new task priority");
+					priority = value;
+					OnPropertyChanged ("Priority");
+				}
 			}
 		}
 
@@ -114,7 +118,10 @@ Logger.Debug ("Setting new task priority");
 		{
 			get { return category; } 
 			set {
-				category = value as DummyCategory;
+				if (value != category) {
+					category = value as DummyCategory;
+					OnPropertyChanged ("Category");
+				}
 			}
 		}
 		
@@ -128,18 +135,18 @@ Logger.Debug ("Setting new task priority");
 		#region Public Methods
 		public override void Activate ()
 		{
-Logger.Debug ("DummyTask.Activate ()");
+			Logger.Debug ("DummyTask.Activate ()");
 			completionDate = DateTime.MinValue;
 			state = TaskState.Active;
-			backend.UpdateTask (this);
+			OnPropertyChanged ("State");
 		}
 		
 		public override void Inactivate ()
 		{
-Logger.Debug ("DummyTask.Inactivate ()");
+			Logger.Debug ("DummyTask.Inactivate ()");
 			completionDate = DateTime.Now;
 			state = TaskState.Inactive;
-			backend.UpdateTask (this);
+			OnPropertyChanged ("State");
 		}
 		
 		public override void Complete ()
@@ -147,14 +154,14 @@ Logger.Debug ("DummyTask.Inactivate ()");
 			Logger.Debug ("DummyTask.Complete ()");
 			CompletionDate = DateTime.Now;
 			state = TaskState.Completed;
-			backend.UpdateTask (this);
+			OnPropertyChanged ("State");
 		}
 		
 		public override void Delete ()
 		{
-Logger.Debug ("DummyTask.Delete ()");
+			Logger.Debug ("DummyTask.Delete ()");
 			state = TaskState.Deleted;
-			backend.UpdateTask (this);
+			OnPropertyChanged ("State");
 		}
 		
 		public override INote CreateNote(string text)
diff --git a/src/tasque/CompletedTaskGroup.cs b/src/tasque/CompletedTaskGroup.cs
index c663f29..43e5c0b 100644
--- a/src/tasque/CompletedTaskGroup.cs
+++ b/src/tasque/CompletedTaskGroup.cs
@@ -10,6 +10,9 @@ using Mono.Unix;
 using System.Collections.ObjectModel;
 using System.Collections.Generic;
 using System.Linq;
+using System.Collections;
+using CollectionTransforms;
+using System.ComponentModel;
 
 namespace Tasque
 {
@@ -24,14 +27,25 @@ namespace Tasque
 	
 	public class CompletedTaskGroup : TaskGroup
 	{
+		/// <summary>
+		/// The purpose of this method is to allow the CompletedTaskGroup to show
+		/// completed tasks in reverse order (i.e., most recently completed tasks
+		/// at the top of the list).
+		/// </summary>
+		static IEnumerable GetSortedTasks (IEnumerable tasks)
+		{
+			var cv = new CollectionView<ITask> (tasks);
+			cv.SortDescriptions.Add (new SortDescription ("CompletionDate", ListSortDirection.Descending));
+			return cv;
+		}
+		
 		ICategory selectedCategory;
 		HScale rangeSlider;
 		ShowCompletedRange currentRange;
 		
 		public CompletedTaskGroup (string groupName, DateTime rangeStart,
-								   DateTime rangeEnd, IEnumerable<ITask> tasks)
-			: base (groupName, rangeStart, rangeEnd,
-					tasks.OrderBy (f => f, new CompletedTasksComparer ()))
+								   DateTime rangeEnd, IEnumerable tasks)
+			: base (groupName, rangeStart, rangeEnd, GetSortedTasks (tasks))
 		{
 			// Don't hide this group when it's empty because then the range
 			// slider won't appear and the user won't be able to customize the
@@ -80,7 +94,7 @@ namespace Tasque
 
 		protected override TaskGroupModel CreateModel (DateTime rangeStart,
 		                                               DateTime rangeEnd,
-		                                               IEnumerable<ITask> tasks)
+		                                               IEnumerable tasks)
 		{
 			return new CompletedTaskGroupModel (rangeStart, rangeEnd, tasks);
 		}
@@ -208,17 +222,4 @@ namespace Tasque
 			this.TimeRangeStart = date;
 		}
 	}
-
-	/// <summary>
-	/// The purpose of this class is to allow the CompletedTaskGroup to show
-	/// completed tasks in reverse order (i.e., most recently completed tasks
-	/// at the top of the list).
-	/// </summary>
-	class CompletedTasksComparer : Comparer<ITask>
-	{
-		public override int Compare (ITask x, ITask y)
-		{
-			return x.CompareToByCompletionDate (y);
-		}
-	}
 }
diff --git a/src/tasque/CompletedTaskGroupModel.cs b/src/tasque/CompletedTaskGroupModel.cs
index 3ecbf3a..53e7ac7 100644
--- a/src/tasque/CompletedTaskGroupModel.cs
+++ b/src/tasque/CompletedTaskGroupModel.cs
@@ -1,14 +1,36 @@
-
+// 
+// CompletedTaskGroupModel.cs
+//  
+// Author:
+//       Antonius Riha <antoniusriha gmail com>
+// 
+// Copyright (c) 2012 Antonius Riha
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
 using System;
-using Gtk;
-using System.Collections.ObjectModel;
-using System.Collections.Generic;
+using System.Collections;
 
 namespace Tasque
 {
 	public class CompletedTaskGroupModel : TaskGroupModel
 	{
-		public CompletedTaskGroupModel (DateTime rangeStart, DateTime rangeEnd, IEnumerable<ITask> tasks)
+		public CompletedTaskGroupModel (DateTime rangeStart, DateTime rangeEnd, IEnumerable tasks)
 			: base (rangeStart, rangeEnd, tasks)
 		{
 		}
@@ -26,19 +48,18 @@ namespace Tasque
 		/// <returns>
 		/// A <see cref="System.Boolean"/>
 		/// </returns>
-		protected override bool FilterTasks (TreeModel model, TreeIter iter)
+		protected override bool FilterTasks (ITask task)
 		{
 			// Don't show any task here if showCompletedTasks is false
-			if (!showCompletedTasks)
+			if (!ShowCompletedTasks)
 				return false;
 			
-			ITask task = model.GetValue (iter, 0) as ITask;
 			if (task == null || task.State != TaskState.Completed)
 				return false;
 			
 			// Make sure that the task fits into the specified range depending
 			// on what the user has set the range slider to be.
-			if (task.CompletionDate < this.timeRangeStart)
+			if (task.CompletionDate < TimeRangeStart)
 				return false;
 			
 			if (task.CompletionDate == DateTime.MinValue)
diff --git a/src/tasque/TaskGroup.cs b/src/tasque/TaskGroup.cs
index 4228a5b..0e4d29f 100644
--- a/src/tasque/TaskGroup.cs
+++ b/src/tasque/TaskGroup.cs
@@ -1,11 +1,33 @@
 // TaskGroup.cs created with MonoDevelop
 // User: boyd at 7:50 PMÂ2/11/2008
-
+// 
+// TaskGroup.cs
+//  
+// Author:
+//       Antonius Riha <antoniusriha gmail com>
+// 
+// Copyright (c) 2012 Antonius Riha
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
 using System;
-using Gdk;
 using Gtk;
-using System.Collections.ObjectModel;
-using System.Collections.Generic;
+using System.Collections;
 
 namespace Tasque
 {
@@ -26,7 +48,7 @@ namespace Tasque
 		
 		#region Constructor
 		public TaskGroup (string groupName, DateTime rangeStart,
-						  DateTime rangeEnd, IEnumerable<ITask> tasks)
+						  DateTime rangeEnd, IEnumerable tasks)
 		{
 			hideWhenEmpty = true;
 						
@@ -86,7 +108,8 @@ namespace Tasque
 			//
 			// Group TreeView
 			//
-			treeView = new TaskTreeView (filteredTasks);
+			var adapter = new TreeModelListAdapter<ITask> (filteredTasks);
+			treeView = new TaskTreeView (adapter);
 			treeView.Show ();
 			PackStart (treeView, true, true, 0);
 			
@@ -187,7 +210,7 @@ namespace Tasque
 		#region Public Methods
 		public void Refilter (ICategory selectedCategory)
 		{
-			filteredTasks.Refilter ();
+			filteredTasks.Refresh ();
 			treeView.Refilter (selectedCategory);
 		}
 		
@@ -327,13 +350,13 @@ namespace Tasque
 			header.Markup = GetHeaderMarkup (DisplayName);
 		}
 
-		protected virtual  TaskGroupModel CreateModel (DateTime rangeStart,
+		protected virtual TaskGroupModel CreateModel (DateTime rangeStart,
 		                                               DateTime rangeEnd,
-		                                               IEnumerable<ITask> tasks)
+		                                               IEnumerable tasks)
 		{
 			return new TaskGroupModel (rangeStart, rangeEnd, tasks);
 		}
-		
+
 		/// <summary>
 		/// Refilter the hard way by discovering the category to filter on
 		/// </summary>
diff --git a/src/tasque/TaskGroupModel.cs b/src/tasque/TaskGroupModel.cs
index 4da66c1..5ee4e95 100644
--- a/src/tasque/TaskGroupModel.cs
+++ b/src/tasque/TaskGroupModel.cs
@@ -1,69 +1,92 @@
-
+// 
+// TaskGroupModel.cs
+//  
+// Author:
+//       Antonius Riha <antoniusriha gmail com>
+// 
+// Copyright (c) 2012 Antonius Riha
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
 using System;
-using System.Collections.ObjectModel;
-using Gtk;
-using System.Collections.Generic;
+using System.Collections;
+using CollectionTransforms;
 
 namespace Tasque
 {
-	public class TaskGroupModel : TreeModelFilter
+	public class TaskGroupModel : CollectionView<ITask>
 	{
 		public bool ShowCompletedTasks {
 			get { return showCompletedTasks; }
 			set {
+				if (showCompletedTasks == value)
+					return;
+				
 				showCompletedTasks = value;
-				base.Refilter ();
+				Refresh ();
 			}
 		}
-
-		public DateTime TimeRangeStart {
-			get { return timeRangeStart; }
-		}
-
-		public DateTime TimeRangeEnd {
-			get { return timeRangeEnd; }
-		}
 		
-		public TaskGroupModel (DateTime rangeStart, DateTime rangeEnd,
-		                       IEnumerable<ITask> tasks)
-			: base (new TreeModelAdapter (new TreeViewModelImplementor<ITask> (tasks)), null)
+		public DateTime TimeRangeStart { get; private set; }
+		
+		public DateTime TimeRangeEnd { get; private set; }
+		
+		public TaskGroupModel (DateTime rangeStart, DateTime rangeEnd, IEnumerable tasks)
+			: base (tasks)
 		{
-			this.timeRangeStart = rangeStart;
-			this.timeRangeEnd = rangeEnd;
+			TimeRangeStart = rangeStart;
+			TimeRangeEnd = rangeEnd;
 
-			base.VisibleFunc = FilterTasks;
+			Filter = FilterTasks;
+			int i = 5;
 		}
-
+		
 		public void SetRange (DateTime rangeStart, DateTime rangeEnd)
 		{
-			this.timeRangeStart = rangeStart;
-			this.timeRangeEnd = rangeEnd;
-			base.Refilter ();
+			if (rangeStart == TimeRangeStart && rangeEnd == TimeRangeEnd)
+				return;
+			
+			TimeRangeStart = rangeStart;
+			TimeRangeEnd = rangeEnd;
+			Refresh ();
 		}
-
+		
 		/// <summary>
 		/// Filter out tasks that don't fit within the group's date range
 		/// </summary>
-		protected virtual bool FilterTasks (Gtk.TreeModel model, Gtk.TreeIter iter)
+		protected virtual bool FilterTasks (ITask task)
 		{
-			ITask task = model.GetValue (iter, 0) as ITask;
 			if (task == null || task.State == TaskState.Deleted)
 				return false;
 			
 			// Do something special when task.DueDate == DateTime.MinValue since
 			// these tasks should always be in the very last category.
 			if (task.DueDate == DateTime.MinValue) {
-				if (timeRangeEnd == DateTime.MaxValue) {
+				if (TimeRangeEnd == DateTime.MaxValue) {
 					if (!ShowCompletedTask (task))
 						return false;
 					
 					return true;
-				} else {
+				} else
 					return false;
-				}
 			}
 			
-			if (task.DueDate < timeRangeStart || task.DueDate > timeRangeEnd)
+			if (task.DueDate < TimeRangeStart || task.DueDate > TimeRangeEnd)
 				return false;
 			
 			if (!ShowCompletedTask (task))
@@ -72,11 +95,13 @@ namespace Tasque
 			return true;
 		}
 		
-		protected DateTime timeRangeStart;
-		protected DateTime timeRangeEnd;
-		protected bool showCompletedTasks = false;
-
-		private bool ShowCompletedTask (ITask task)
+		bool IsToday (DateTime date)
+		{
+			DateTime today = DateTime.Now;
+			return today.Year == date.Year && today.DayOfYear == date.DayOfYear;
+		}
+		
+		bool ShowCompletedTask (ITask task)
 		{
 			if (task.State == TaskState.Completed) {
 				if (!showCompletedTasks)
@@ -95,14 +120,6 @@ namespace Tasque
 			return true;
 		}
 		
-		private bool IsToday (DateTime testDate)
-		{
-			DateTime today = DateTime.Now;
-			if (today.Year != testDate.Year
-				|| today.DayOfYear != testDate.DayOfYear)
-				return false;
-			
-			return true;
-		}
+		bool showCompletedTasks;
 	}
 }
diff --git a/src/tasque/TaskGroupModelFactory.cs b/src/tasque/TaskGroupModelFactory.cs
index c0f4cec..e67e857 100644
--- a/src/tasque/TaskGroupModelFactory.cs
+++ b/src/tasque/TaskGroupModelFactory.cs
@@ -1,15 +1,36 @@
-
+// 
+// TaskGroupModelFactory.cs
+//  
+// Author:
+//       Antonius Riha <antoniusriha gmail com>
+// 
+// Copyright (c) 2012 Antonius Riha
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
 using System;
-
-using Gtk;
-using System.Collections.ObjectModel;
-using System.Collections.Generic;
+using System.Collections;
 
 namespace Tasque
 {
 	public static class TaskGroupModelFactory
 	{
-		public static TaskGroupModel CreateTodayModel (IEnumerable<ITask> tasks)
+		public static TaskGroupModel CreateTodayModel (IEnumerable tasks)
 		{
 			DateTime rangeStart = DateTime.Now;
 			rangeStart = new DateTime (rangeStart.Year, rangeStart.Month,
@@ -20,7 +41,7 @@ namespace Tasque
 			return new TaskGroupModel (rangeStart, rangeEnd, tasks);
 		}
 
-		public static TaskGroupModel CreateOverdueModel (IEnumerable<ITask> tasks)
+		public static TaskGroupModel CreateOverdueModel (IEnumerable tasks)
 		{
 			DateTime rangeStart = DateTime.MinValue;
 			DateTime rangeEnd = DateTime.Now.AddDays (-1);
@@ -30,7 +51,7 @@ namespace Tasque
 			return new TaskGroupModel (rangeStart, rangeEnd, tasks);
 		}
 
-		public static TaskGroupModel CreateTomorrowModel (IEnumerable<ITask> tasks)
+		public static TaskGroupModel CreateTomorrowModel (IEnumerable tasks)
 		{
 			DateTime rangeStart = DateTime.Now.AddDays (1);
 			rangeStart = new DateTime (rangeStart.Year, rangeStart.Month,