AvalonEdit: Initial implementation of virtual space.

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

@@ -289,7 +289,7 @@ void RevalidateVisualColumn(VisualLine visualLine)
 				if (offsetFromVisualColumn != caretOffset) {
 					position.VisualColumn = visualLine.GetVisualColumn(caretOffset - firstDocumentLineOffset);
 				} else {
-					if (position.VisualColumn > visualLine.VisualLength) {
+					if (position.VisualColumn > visualLine.VisualLength && !textArea.Options.EnableVirtualSpace) {
 						position.VisualColumn = visualLine.VisualLength;
 					}
 				}
@@ -347,7 +347,7 @@ Rect CalcCaretRectangle(VisualLine visualLine)
 			}
 
 			TextLine textLine = visualLine.GetTextLine(position.VisualColumn);
-			double xPos = textLine.GetDistanceFromCharacterHit(new CharacterHit(position.VisualColumn, 0));
+			double xPos = visualLine.GetTextLineVisualXPosition(textLine, position.VisualColumn);
 			double lineTop = visualLine.GetTextLineVisualYPosition(textLine, VisualYPosition.TextTop);
 			double lineBottom = visualLine.GetTextLineVisualYPosition(textLine, VisualYPosition.LineBottom);
 

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

@@ -4,10 +4,10 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Windows;
 using System.Windows.Documents;
 using System.Windows.Input;
 using System.Windows.Media.TextFormatting;
-
 using ICSharpCode.AvalonEdit.Document;
 using ICSharpCode.AvalonEdit.Rendering;
 using ICSharpCode.AvalonEdit.Utils;
@@ -250,7 +250,7 @@ static void MoveCaretUpDown(TextArea textArea, CaretMovementType direction, Visu
 			// moving up/down happens using the desired visual X position
 			double xPos = textArea.Caret.DesiredXPos;
 			if (double.IsNaN(xPos))
-				xPos = textLine.GetDistanceFromCharacterHit(new CharacterHit(caretVisualColumn, 0));
+				xPos = visualLine.GetTextLineVisualXPosition(textLine, caretVisualColumn);
 			// now find the TextLine+VisualLine where the caret will end up in
 			VisualLine targetVisualLine = visualLine;
 			TextLine targetLine;
@@ -306,21 +306,23 @@ static void MoveCaretUpDown(TextArea textArea, CaretMovementType direction, Visu
 					throw new NotSupportedException(direction.ToString());
 			}
 			if (targetLine != null) {
-				CharacterHit ch = targetLine.GetCharacterHitFromDistance(xPos);
-				SetCaretPosition(textArea, targetVisualLine, targetLine, ch, false);
+				double yPos = targetVisualLine.GetTextLineVisualYPosition(targetLine, VisualYPosition.LineMiddle);
+				int newVisualColumn = targetVisualLine.GetVisualColumn(new Point(xPos, yPos));
+				SetCaretPosition(textArea, targetVisualLine, targetLine, newVisualColumn, false);
 				textArea.Caret.DesiredXPos = xPos;
 			}
 		}
 		#endregion
 
 		#region SetCaretPosition
 		static void SetCaretPosition(TextArea textArea, VisualLine targetVisualLine, TextLine targetLine,
-		                             CharacterHit ch, bool allowWrapToNextLine)
+		                             int newVisualColumn, bool allowWrapToNextLine)
 		{
-			int newVisualColumn = ch.FirstCharacterIndex + ch.TrailingLength;
 			int targetLineStartCol = targetVisualLine.GetTextLineVisualStartColumn(targetLine);
-			if (!allowWrapToNextLine && newVisualColumn >= targetLineStartCol + targetLine.Length)
-				newVisualColumn = targetLineStartCol + targetLine.Length - 1;
+			if (!allowWrapToNextLine && newVisualColumn >= targetLineStartCol + targetLine.Length) {
+				if (newVisualColumn <= targetVisualLine.VisualLength)
+					newVisualColumn = targetLineStartCol + targetLine.Length - 1;
+			}
 			int newOffset = targetVisualLine.GetRelativeOffset(newVisualColumn) + targetVisualLine.FirstDocumentLine.Offset;
 			SetCaretPosition(textArea, newVisualColumn, newOffset);
 		}

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

@@ -13,7 +13,7 @@
 namespace ICSharpCode.AvalonEdit.Editing
 {
 	/// <summary>
-	/// Rectangular selection.
+	/// Rectangular selection ("box selection").
 	/// </summary>
 	public sealed class RectangleSelection : Selection
 	{

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Rendering/BackgroundGeometryBuilder.cs

@@ -129,7 +129,7 @@ static IEnumerable<Rect> GetRectsForSegmentImpl(TextView textView, ISegment segm
 					if (segmentStartVCInLine == segmentEndVCInLine) {
 						// GetTextBounds crashes for length=0, so we'll handle this case with GetDistanceFromCharacterHit
 						// We need to return a rectangle to ensure empty lines are still visible
-						double pos = line.GetDistanceFromCharacterHit(new CharacterHit(segmentStartVCInLine, 0));
+						double pos = vl.GetTextLineVisualXPosition(line, segmentStartVCInLine);
 						pos -= scrollOffset.X;
 						// The following special cases are necessary to get rid of empty rectangles at the end of a TextLine if "Show Spaces" is active.
 						// If not excluded once, the same rectangle is calculated (and added) twice (since the offset could be mapped to two visual positions; end/start of line), if there is no trailing whitespace.

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Rendering/TextView.cs

@@ -1360,7 +1360,7 @@ void IScrollInfo.MouseWheelRight()
 		double wideSpaceWidth; // Width of an 'x'. Used as basis for the tab width, and for scrolling.
 		double defaultLineHeight; // Height of a line containing 'x'. Used for scrolling.
 
-		double WideSpaceWidth {
+		internal double WideSpaceWidth {
 			get {
 				if (wideSpaceWidth == 0) {
 					MeasureWideSpaceWidthAndDefaultLineHeight();

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Rendering/VisualLine.cs

@@ -224,8 +224,9 @@ public int GetRelativeOffset(int visualColumn)
 		/// </summary>
 		public TextLine GetTextLine(int visualColumn)
 		{
-			ThrowUtil.CheckInRangeInclusive(visualColumn, "visualColumn", 0, VisualLength);
-			if (visualColumn == VisualLength)
+			if (visualColumn < 0)
+				throw new ArgumentOutOfRangeException("visualColumn");
+			if (visualColumn >= VisualLength)
 				return TextLines[TextLines.Count - 1];
 			foreach (TextLine line in TextLines) {
 				if (visualColumn < line.Length)
@@ -307,18 +308,45 @@ public TextLine GetTextLineByVisualYPosition(double visualTop)
 		public Point GetVisualPosition(int visualColumn, VisualYPosition yPositionMode)
 		{
 			TextLine textLine = GetTextLine(visualColumn);
-			double xPos = textLine.GetDistanceFromCharacterHit(new CharacterHit(visualColumn, 0));
+			double xPos = GetTextLineVisualXPosition(textLine, visualColumn);
 			double yPos = GetTextLineVisualYPosition(textLine, yPositionMode);
 			return new Point(xPos, yPos);
 		}
 
+		/// <summary>
+		/// Gets the distance to the left border of the text area of the specified visual column.
+		/// The visual column must belong to the specified text line.
+		/// </summary>
+		public double GetTextLineVisualXPosition(TextLine textLine, int visualColumn)
+		{
+			if (textLine == null)
+				throw new ArgumentNullException("textLine");
+			double xPos = textLine.GetDistanceFromCharacterHit(
+				new CharacterHit(Math.Min(visualColumn, VisualLength), 0));
+			if (visualColumn > VisualLength) {
+				xPos += (visualColumn - VisualLength) * textView.WideSpaceWidth;
+			}
+			return xPos;
+		}
+
 		/// <summary>
 		/// Gets the visual column from a document position (relative to top left of the document).
 		/// If the user clicks between two visual columns, rounds to the nearest column.
 		/// </summary>
 		public int GetVisualColumn(Point point)
+		{
+			return GetVisualColumn(point, textView.Options.EnableVirtualSpace);
+		}
+
+		public int GetVisualColumn(Point point, bool allowVirtualSpace)
 		{
 			TextLine textLine = GetTextLineByVisualYPosition(point.Y);
+			if (point.X > textLine.WidthIncludingTrailingWhitespace) {
+				if (allowVirtualSpace && textLine == TextLines[TextLines.Count - 1]) {
+					int virtualX = (int)Math.Round((point.X - textLine.WidthIncludingTrailingWhitespace) / textView.WideSpaceWidth);
+					return VisualLength + virtualX;
+				}
+			}
 			CharacterHit ch = textLine.GetCharacterHitFromDistance(point.X);
 			return ch.FirstCharacterIndex + ch.TrailingLength;
 		}
@@ -328,13 +356,24 @@ public int GetVisualColumn(Point point)
 		/// If the user clicks between two visual columns, returns the first of those columns.
 		/// </summary>
 		public int GetVisualColumnFloor(Point point)
+		{
+			return GetVisualColumnFloor(point, textView.Options.EnableVirtualSpace);
+		}
+
+		public int GetVisualColumnFloor(Point point, bool allowVirtualSpace)
 		{
 			TextLine textLine = GetTextLineByVisualYPosition(point.Y);
 			if (point.X > textLine.WidthIncludingTrailingWhitespace) {
-				// GetCharacterHitFromDistance returns a hit with FirstCharacterIndex=last character inline
-				// and TrailingLength=1 when clicking behind the line, so the floor function needs to handle this case
-				// specially end return the line's end column instead.
-				return GetTextLineVisualStartColumn(textLine) + textLine.Length;
+				if (allowVirtualSpace && textLine == TextLines[TextLines.Count - 1]) {
+					// clicking virtual space in the last line
+					int virtualX = (int)((point.X - textLine.WidthIncludingTrailingWhitespace) / textView.WideSpaceWidth);
+					return VisualLength + virtualX;
+				} else {
+					// GetCharacterHitFromDistance returns a hit with FirstCharacterIndex=last character in line
+					// and TrailingLength=1 when clicking behind the line, so the floor function needs to handle this case
+					// specially and return the line's end column instead.
+					return GetTextLineVisualStartColumn(textLine) + textLine.Length;
+				}
 			}
 			CharacterHit ch = textLine.GetCharacterHitFromDistance(point.X);
 			return ch.FirstCharacterIndex;
@@ -352,14 +391,23 @@ public int GetNextCaretPosition(int visualColumn, LogicalDirection direction, Ca
 		{
 			if (elements.Count == 0) {
 				// special handling for empty visual lines:
-				// even though we don't have any elements,
-				// there's a single caret stop at visualColumn 0
-				if (visualColumn < 0 && direction == LogicalDirection.Forward)
-					return 0;
-				else if (visualColumn > 0 && direction == LogicalDirection.Backward)
-					return 0;
-				else
-					return -1;
+				if (textView.Options.EnableVirtualSpace) {
+					if (direction == LogicalDirection.Forward)
+						return Math.Max(0, visualColumn + 1);
+					else if (visualColumn > 0)
+						return visualColumn - 1;
+					else
+						return -1;
+				} else {
+					// even though we don't have any elements,
+					// there's a single caret stop at visualColumn 0
+					if (visualColumn < 0 && direction == LogicalDirection.Forward)
+						return 0;
+					else if (visualColumn > 0 && direction == LogicalDirection.Backward)
+						return 0;
+					else
+						return -1;
+				}
 			}
 
 			int i;
@@ -368,7 +416,10 @@ public int GetNextCaretPosition(int visualColumn, LogicalDirection direction, Ca
 				// If the last element doesn't handle line borders, return the line end as caret stop
 
 				if (visualColumn > this.VisualLength && !elements[elements.Count-1].HandlesLineBorders && HasImplicitStopAtLineEnd(mode)) {
-					return this.VisualLength;
+					if (textView.Options.EnableVirtualSpace)
+						return visualColumn - 1;
+					else
+						return this.VisualLength;
 				}
 				// skip elements that start after or at visualColumn
 				for (i = elements.Count - 1; i >= 0; i--) {
@@ -407,8 +458,12 @@ public int GetNextCaretPosition(int visualColumn, LogicalDirection direction, Ca
 				}
 				// if we've found nothing, and the last element doesn't handle line borders,
 				// return the line end as caret stop
-				if (visualColumn < this.VisualLength && !elements[elements.Count-1].HandlesLineBorders && HasImplicitStopAtLineEnd(mode))
-					return this.VisualLength;
+				if (!elements[elements.Count-1].HandlesLineBorders && HasImplicitStopAtLineEnd(mode)) {
+					if (visualColumn < this.VisualLength)
+						return this.VisualLength;
+					else if (textView.Options.EnableVirtualSpace)
+						return visualColumn + 1;
+				}
 			}
 			// we've found nothing, return -1 and let the caret search continue in the next line
 			return -1;

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/TextEditorOptions.cs

@@ -362,5 +362,24 @@ public virtual string GetIndentationString(int column)
 				}
 			}
 		}
+
+		bool enableVirtualSpace;
+
+		/// <summary>
+		/// Gets/Sets whether the user can set the caret behind the line ending
+		/// (into "virtual space").
+		/// Note that virtual space is always used (independent from this setting)
+		/// when doing rectangle selections.
+		/// </summary>
+		[DefaultValue(false)]
+		public virtual bool EnableVirtualSpace {
+			get { return enableVirtualSpace; }
+			set {
+				if (enableVirtualSpace != value) {
+					enableVirtualSpace = value;
+					OnPropertyChanged("EnableVirtualSpace");
+				}
+			}
+		}
 	}
 }