Initial Commit

Common/UndoSystem/UndoProvider.cs

@@ -0,0 +1,154 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.ComponentModel;
+using System.Windows;
+
+namespace Microsoft.Research.DynamicDataDisplay.Common.UndoSystem
+{
+	public class UndoProvider : INotifyPropertyChanged
+	{
+		private readonly ActionStack undoStack = new ActionStack();
+		private readonly ActionStack redoStack = new ActionStack();
+
+		public UndoProvider()
+		{
+			undoStack.IsEmptyChanged += OnUndoStackIsEmptyChanged;
+			redoStack.IsEmptyChanged += OnRedoStackIsEmptyChanged;
+		}
+
+		private bool isEnabled = true;
+		public bool IsEnabled
+		{
+			get { return isEnabled; }
+			set { isEnabled = value; }
+		}
+
+		private void OnUndoStackIsEmptyChanged(object sender, EventArgs e)
+		{
+			PropertyChanged.Raise(this, "CanUndo");
+		}
+
+		private void OnRedoStackIsEmptyChanged(object sender, EventArgs e)
+		{
+			PropertyChanged.Raise(this, "CanRedo");
+		}
+
+		public void AddAction(UndoAction action)
+		{
+			if (!isEnabled)
+				return;
+
+			if (state != UndoState.None)
+				return;
+
+			undoStack.Push(action);
+			redoStack.Clear();
+		}
+
+		public void Undo()
+		{
+			var action = undoStack.Pop();
+			redoStack.Push(action);
+
+			state = UndoState.Undoing;
+			try
+			{
+				action.Undo();
+			}
+			finally
+			{
+				state = UndoState.None;
+			}
+		}
+
+		public void Redo()
+		{
+			var action = redoStack.Pop();
+			undoStack.Push(action);
+
+			state = UndoState.Redoing;
+			try
+			{
+				action.Do();
+			}
+			finally
+			{
+				state = UndoState.None;
+			}
+		}
+
+		public bool CanUndo
+		{
+			get { return !undoStack.IsEmpty; }
+		}
+
+		public bool CanRedo
+		{
+			get { return !redoStack.IsEmpty; }
+		}
+
+		private UndoState state = UndoState.None;
+		public UndoState State
+		{
+			get { return state; }
+		}
+
+		#region INotifyPropertyChanged Members
+
+		public event PropertyChangedEventHandler PropertyChanged;
+
+		#endregion
+
+		private readonly Dictionary<CaptureKeyHolder, object> captureHolders = new Dictionary<CaptureKeyHolder, object>();
+		public void CaptureOldValue(DependencyObject target, DependencyProperty property, object oldValue)
+		{
+			captureHolders[new CaptureKeyHolder { Target = target, Property = property }] = oldValue;
+		}
+
+		public void CaptureNewValue(DependencyObject target, DependencyProperty property, object newValue)
+		{
+			var holder = new CaptureKeyHolder { Target = target, Property = property };
+			if (captureHolders.ContainsKey(holder))
+			{
+				object oldValue = captureHolders[holder];
+				captureHolders.Remove(holder);
+
+				if (!Object.Equals(oldValue, newValue))
+				{
+					var action = new DependencyPropertyChangedUndoAction(target, property, oldValue, newValue);
+					AddAction(action);
+				}
+			}
+		}
+
+		private sealed class CaptureKeyHolder
+		{
+			public DependencyObject Target { get; set; }
+			public DependencyProperty Property { get; set; }
+
+			public override int GetHashCode()
+			{
+				return Target.GetHashCode() ^ Property.GetHashCode();
+			}
+
+			public override bool Equals(object obj)
+			{
+				if (obj == null) return false;
+
+				CaptureKeyHolder other = obj as CaptureKeyHolder;
+				if (other == null) return false;
+
+				return Target == other.Target && Property == other.Property;
+			}
+		}
+	}
+
+	public enum UndoState
+	{
+		None,
+		Undoing,
+		Redoing
+	}
+}