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Using AvalonEdit (WPF Text Editor)

, 1 Apr 2013
AvalonEdit is an extensible Open-Source text editor with support for syntax highlighting and folding.
AvalonEdit_4.3.1_Binaries-noexe.zip
AvalonEdit_4.3.1_Binaries.zip
AvalonEdit_4.3.1_Source-noexe.zip
AvalonEdit.Sample
AvalonEdit
dependencies.png
folding.png
renderingPipeline.png
screenshot.png
snoop.png
CustomHighlighting.xshd
Images
Copy.png
Cut.png
Delete.png
Open.png
Paste.png
Redo.png
Save.png
Undo.png
WordWrap.png
Properties
RenderingPipeline.pptx
Documentation
Architecture.aml
Code Completion.aml
Coordinate Systems.aml
Folding.aml
ICSharpCode.AvalonEdit.content
ICSharpCode.AvalonEdit.shfbproj
Media
NamespaceDependencies.png
RenderingPipeline.png
VisualTree.png
WelcomeScreenshot.png
Sample Application.aml
Syntax Highlighting.aml
Text Rendering.aml
Welcome.aml
ICSharpCode.AvalonEdit.Tests
Document
Editing
Highlighting
ICSharpCode.AvalonEdit.Tests.PartCover.Settings
Properties
Search
Utils
ICSharpCode.AvalonEdit
CodeCompletion
Document
Editing
Folding
Highlighting
Resources
ASPX.xshd
Boo.xshd
Coco-Mode.xshd
CPP-Mode.xshd
CSharp-Mode.xshd
CSS-Mode.xshd
HTML-Mode.xshd
Java-Mode.xshd
JavaScript-Mode.xshd
MarkDown-Mode.xshd
Patch-Mode.xshd
PHP-Mode.xshd
PowerShell.xshd
Tex-Mode.xshd
VBNET-Mode.xshd
XML-Mode.xshd
XmlDoc.xshd
Xshd
ICSharpCode.AvalonEdit.snk
Indentation
CSharp
Properties
Rendering
Search
next.png
prev.png
Snippets
themes
RightArrow.cur
Utils
Xml
AvalonEdit_4.3.1_Source.zip
dependencies.png
folding.png
renderingPipeline.png
screenshot.png
snoop.png
CustomHighlighting.xshd
Copy.png
Cut.png
Delete.png
Open.png
Paste.png
Redo.png
Save.png
Undo.png
WordWrap.png
RenderingPipeline.pptx
Architecture.aml
Code Completion.aml
Coordinate Systems.aml
Folding.aml
ICSharpCode.AvalonEdit.content
ICSharpCode.AvalonEdit.shfbproj
NamespaceDependencies.png
RenderingPipeline.png
VisualTree.png
WelcomeScreenshot.png
Sample Application.aml
Syntax Highlighting.aml
Text Rendering.aml
Welcome.aml
ICSharpCode.AvalonEdit.Tests.PartCover.Settings
nunit.framework.dll
ASPX.xshd
Boo.xshd
Coco-Mode.xshd
CPP-Mode.xshd
CSharp-Mode.xshd
CSS-Mode.xshd
HTML-Mode.xshd
Java-Mode.xshd
JavaScript-Mode.xshd
MarkDown-Mode.xshd
Patch-Mode.xshd
PHP-Mode.xshd
PowerShell.xshd
Tex-Mode.xshd
VBNET-Mode.xshd
XML-Mode.xshd
XmlDoc.xshd
ICSharpCode.AvalonEdit.snk
next.png
prev.png
RightArrow.cur
AvalonEdit_Binaries-noexe.zip
AvalonEdit_Binaries.zip
AvalonEdit_CHM_Documentation.zip
AvalonEdit_Source.zip
dependencies.png
folding.png
renderingPipeline.png
screenshot.png
snoop.png
CustomHighlighting.xshd
Copy.png
Cut.png
Delete.png
Open.png
Paste.png
Redo.png
Save.png
Undo.png
WordWrap.png
RenderingPipeline.pptx
Architecture.aml
Code Completion.aml
Coordinate Systems.aml
Folding.aml
Help
ICSharpCode.AvalonEdit.content
ICSharpCode.AvalonEdit.shfbproj
NamespaceDependencies.png
RenderingPipeline.png
VisualTree.png
WelcomeScreenshot.png
Sample Application.aml
Syntax Highlighting.aml
Text Rendering.aml
Welcome.aml
ICSharpCode.AvalonEdit.Tests.PartCover.Settings
nunit.framework.dll
ASPX.xshd
Boo.xshd
Coco-Mode.xshd
CPP-Mode.xshd
CSharp-Mode.xshd
CSS-Mode.xshd
HTML-Mode.xshd
Java-Mode.xshd
JavaScript-Mode.xshd
Patch-Mode.xshd
PHP-Mode.xshd
PowerShell.xshd
Tex-Mode.xshd
VBNET-Mode.xshd
XML-Mode.xshd
XmlDoc.xshd
ICSharpCode.AvalonEdit.snk
next.png
prev.png
RightArrow.cur
// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)

using System;
using System.Diagnostics;
using System.Text;

using ICSharpCode.AvalonEdit.Utils;

namespace ICSharpCode.AvalonEdit.Document
{
	/*
	/// <summary>
	/// Implementation of a gap text buffer.
	/// </summary>
	sealed class GapTextBuffer
	{
		char[] buffer = Empty<char>.Array;
		
		/// <summary>
		/// The current text content.
		/// Is set to null whenever the buffer changes, and gets a value only when the
		/// full text content is requested.
		/// </summary>
		string textContent;
		
		/// <summary>
		/// last GetText result
		/// </summary>
		string lastGetTextResult;
		int lastGetTextRequestOffset;
		
		int gapBeginOffset;
		int gapEndOffset;
		int gapLength; // gapLength == gapEndOffset - gapBeginOffset
		
		/// <summary>
		/// when gap is too small for inserted text or gap is too large (exceeds maxGapLength),
		/// a new buffer is reallocated with a new gap of at least this size.
		/// </summary>
		const int minGapLength = 128;
		
		/// <summary>
		/// when the gap exceeds this size, reallocate a smaller buffer
		/// </summary>
		const int maxGapLength = 4096;
		
		public int Length {
			get {
				return buffer.Length - gapLength;
			}
		}
		
		/// <summary>
		/// Gets the buffer content.
		/// </summary>
		public string Text {
			get {
				if (textContent == null)
					textContent = GetText(0, Length);
				return textContent;
			}
			set {
				Debug.Assert(value != null);
				textContent = value;  lastGetTextResult = null;
				buffer = new char[value.Length + minGapLength];
				value.CopyTo(0, buffer, 0, value.Length);
				gapBeginOffset = value.Length;
				gapEndOffset = buffer.Length;
				gapLength = gapEndOffset - gapBeginOffset;
			}
		}
		
		public char GetCharAt(int offset)
		{
			return offset < gapBeginOffset ? buffer[offset] : buffer[offset + gapLength];
		}
		
		public string GetText(int offset, int length)
		{
			if (length == 0)
				return string.Empty;
			if (lastGetTextRequestOffset == offset && lastGetTextResult != null && length == lastGetTextResult.Length)
				return lastGetTextResult;
			
			int end = offset + length;
			string result;
			if (end < gapBeginOffset) {
				result = new string(buffer, offset, length);
			} else if (offset > gapBeginOffset) {
				result = new string(buffer, offset + gapLength, length);
			} else {
				int block1Size = gapBeginOffset - offset;
				int block2Size = end - gapBeginOffset;
				
				StringBuilder buf = new StringBuilder(block1Size + block2Size);
				buf.Append(buffer, offset,       block1Size);
				buf.Append(buffer, gapEndOffset, block2Size);
				result = buf.ToString();
			}
			lastGetTextRequestOffset = offset;
			lastGetTextResult = result;
			return result;
		}
		
		/// <summary>
		/// Inserts text at the specified offset.
		/// </summary>
		public void Insert(int offset, string text)
		{
			Debug.Assert(offset >= 0 && offset <= Length);
			
			if (text.Length == 0)
				return;
			
			textContent = null; lastGetTextResult = null;
			PlaceGap(offset, text.Length);
			text.CopyTo(0, buffer, gapBeginOffset, text.Length);
			gapBeginOffset += text.Length;
			gapLength = gapEndOffset - gapBeginOffset;
		}
		
		/// <summary>
		/// Remove <paramref name="length"/> characters at <paramref name="offset"/>.
		/// Leave a gap of at least <paramref name="reserveGapSize"/>.
		/// </summary>
		public void Remove(int offset, int length, int reserveGapSize)
		{
			Debug.Assert(offset >= 0 && offset <= Length);
			Debug.Assert(length >= 0 && offset + length <= Length);
			Debug.Assert(reserveGapSize >= 0);
			
			if (length == 0)
				return;
			
			textContent = null; lastGetTextResult = null;
			PlaceGap(offset, reserveGapSize - length);
			gapEndOffset += length; // delete removed text
			gapLength = gapEndOffset - gapBeginOffset;
			if (gapLength - reserveGapSize > maxGapLength && gapLength - reserveGapSize > buffer.Length / 4) {
				// shrink gap
				MakeNewBuffer(gapBeginOffset, reserveGapSize + minGapLength);
			}
		}
		
		void PlaceGap(int newGapOffset, int minRequiredGapLength)
		{
			if (gapLength < minRequiredGapLength) {
				// enlarge gap
				MakeNewBuffer(newGapOffset, minRequiredGapLength + Math.Max(minGapLength, buffer.Length / 8));
			} else {
				while (newGapOffset < gapBeginOffset) {
					buffer[--gapEndOffset] = buffer[--gapBeginOffset];
				}
				while (newGapOffset > gapBeginOffset) {
					buffer[gapBeginOffset++] = buffer[gapEndOffset++];
				}
			}
		}
		
		void MakeNewBuffer(int newGapOffset, int newGapLength)
		{
			char[] newBuffer = new char[Length + newGapLength];
			Debug.WriteLine("GapTextBuffer was reallocated, new size=" + newBuffer.Length);
			if (newGapOffset < gapBeginOffset) {
				// gap is moving backwards
				
				// first part:
				Array.Copy(buffer, 0, newBuffer, 0, newGapOffset);
				// moving middle part:
				Array.Copy(buffer, newGapOffset, newBuffer, newGapOffset + newGapLength, gapBeginOffset - newGapOffset);
				// last part:
				Array.Copy(buffer, gapEndOffset, newBuffer, newBuffer.Length - (buffer.Length - gapEndOffset), buffer.Length - gapEndOffset);
			} else {
				// gap is moving forwards
				// first part:
				Array.Copy(buffer, 0, newBuffer, 0, gapBeginOffset);
				// moving middle part:
				Array.Copy(buffer, gapEndOffset, newBuffer, gapBeginOffset, newGapOffset - gapBeginOffset);
				// last part:
				int lastPartLength = newBuffer.Length - (newGapOffset + newGapLength);
				Array.Copy(buffer, buffer.Length - lastPartLength, newBuffer, newGapOffset + newGapLength, lastPartLength);
			}
			
			gapBeginOffset = newGapOffset;
			gapEndOffset = newGapOffset + newGapLength;
			gapLength = newGapLength;
			buffer = newBuffer;
		}
	}
	*/
}

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Daniel Grunwald

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I am the lead developer on the SharpDevelop open source project.
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