Implement INotifyPropertyChanged in TextDocument.

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/TextDocument.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using System.ComponentModel;
 using System.Diagnostics;
 using System.Linq;
 using System.Globalization;
@@ -21,7 +22,7 @@ namespace ICSharpCode.AvalonEdit.Document
 	/// <inheritdoc cref="VerifyAccess"/>
 	/// <para>However, there is a single method that is thread-safe: <see cref="CreateSnapshot()"/> (and its overloads).</para>
 	/// </remarks>
-	public sealed class TextDocument : ITextSource
+	public sealed class TextDocument : ITextSource, INotifyPropertyChanged
 	{
 		#region Thread ownership
 		readonly object lockObject = new object();
@@ -207,8 +208,16 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// Is raised when the TextLength property changes.
 		/// </summary>
 		/// <remarks><inheritdoc cref="Changing"/></remarks>
+		[Obsolete("This event will be removed in a future version; use the PropertyChanged event instead")]
 		public event EventHandler TextLengthChanged;
 		
+		/// <summary>
+		/// Is raised when one of the properties <see cref="Text"/>, <see cref="TextLength"/>, <see cref="LineCount"/>,
+		/// <see cref="UndoStack"/> changes.
+		/// </summary>
+		/// <remarks><inheritdoc cref="Changing"/></remarks>
+		public event PropertyChangedEventHandler PropertyChanged;
+		
 		/// <summary>
 		/// Is raised before the document changes.
 		/// </summary>
@@ -231,8 +240,7 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// <item><description><b><see cref="EndUpdate">EndUpdate()</see></b></description>
 		///   <list type="bullet">
 		///   <item><description><see cref="TextChanged"/> event is raised</description></item>
-		///   <item><description><see cref="TextLengthChanged"/> event is raised</description></item>
-		///   <item><description><see cref="LineCountChanged"/> event is raised</description></item>
+		///   <item><description><see cref="PropertyChanged"/> event is raised (for the Text, TextLength, LineCount properties, in that order)</description></item>
 		///   <item><description>End of change group (on undo stack)</description></item>
 		///   <item><description><see cref="UpdateFinished"/> event is raised</description></item>
 		///   </list></item>
@@ -418,21 +426,30 @@ namespace ICSharpCode.AvalonEdit.Document
 				fireTextChanged = false;
 				if (TextChanged != null)
 					TextChanged(this, EventArgs.Empty);
+				OnPropertyChanged("Text");
 				
 				int textLength = rope.Length;
 				if (textLength != oldTextLength) {
 					oldTextLength = textLength;
 					if (TextLengthChanged != null)
 						TextLengthChanged(this, EventArgs.Empty);
+					OnPropertyChanged("TextLength");
 				}
 				int lineCount = lineTree.LineCount;
 				if (lineCount != oldLineCount) {
 					oldLineCount = lineCount;
 					if (LineCountChanged != null)
 						LineCountChanged(this, EventArgs.Empty);
+					OnPropertyChanged("LineCount");
 				}
 			}
 		}
+		
+		void OnPropertyChanged(string propertyName)
+		{
+			if (PropertyChanged != null)
+				PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
+		}
 		#endregion
 		
 		#region Insert / Remove  / Replace
@@ -743,6 +760,7 @@ namespace ICSharpCode.AvalonEdit.Document
 					undoStack.ClearAll(); // first clear old undo stack, so that it can't be used to perform unexpected changes on this document
 					// ClearAll() will also throw an exception when it's not safe to replace the undo stack (e.g. update is currently in progress)
 					undoStack = value;
+					OnPropertyChanged("UndoStack");
 				}
 			}
 		}
@@ -775,6 +793,7 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// <summary>
 		/// Is raised when the LineCount property changes.
 		/// </summary>
+		[Obsolete("This event will be removed in a future version; use the PropertyChanged event instead")]
 		public event EventHandler LineCountChanged;
 		#endregion
 		

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/TextDocumentWeakEventManager.cs

@@ -91,6 +91,7 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// Weak event manager for the <see cref="TextDocument.LineCountChanged"/> event.
 		/// </summary>
 		[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1034:NestedTypesShouldNotBeVisible")]
+		[Obsolete("The TextDocument.LineCountChanged event will be removed in a future version. Use PropertyChangedEventManager instead.")]
 		public sealed class LineCountChanged : WeakEventManagerBase<LineCountChanged, TextDocument>
 		{
 			/// <inheritdoc/>
@@ -110,6 +111,7 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// Weak event manager for the <see cref="TextDocument.TextLengthChanged"/> event.
 		/// </summary>
 		[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1034:NestedTypesShouldNotBeVisible")]
+		[Obsolete("The TextDocument.TextLengthChanged event will be removed in a future version. Use PropertyChangedEventManager instead.")]
 		public sealed class TextLengthChanged : WeakEventManagerBase<TextLengthChanged, TextDocument>
 		{
 			/// <inheritdoc/>

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Editing/LineNumberMargin.cs

@@ -2,6 +2,7 @@
 // This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
 
 using System;
+using System.ComponentModel;
 using System.Globalization;
 using System.Windows;
 using System.Windows.Controls;
@@ -89,11 +90,11 @@ namespace ICSharpCode.AvalonEdit.Editing
 		protected override void OnDocumentChanged(TextDocument oldDocument, TextDocument newDocument)
 		{
 			if (oldDocument != null) {
-				TextDocumentWeakEventManager.LineCountChanged.RemoveListener(oldDocument, this);
+				PropertyChangedEventManager.RemoveListener(oldDocument, this, "LineCount");
 			}
 			base.OnDocumentChanged(oldDocument, newDocument);
 			if (newDocument != null) {
-				TextDocumentWeakEventManager.LineCountChanged.AddListener(newDocument, this);
+				PropertyChangedEventManager.AddListener(oldDocument, this, "LineCount");
 			}
 			OnDocumentLineCountChanged();
 		}
@@ -101,7 +102,7 @@ namespace ICSharpCode.AvalonEdit.Editing
 		/// <inheritdoc cref="IWeakEventListener.ReceiveWeakEvent"/>
 		protected virtual bool ReceiveWeakEvent(Type managerType, object sender, EventArgs e)
 		{
-			if (managerType == typeof(TextDocumentWeakEventManager.LineCountChanged)) {
+			if (managerType == typeof(PropertyChangedEventManager)) {
 				OnDocumentLineCountChanged();
 				return true;
 			}