Merge pull request #308 from doug24/right-to-left-flowdirection

Add support for FlowDirection.RightToLeft as overall flow direction of the editor.

ICSharpCode.AvalonEdit/Editing/CaretNavigationCommandHandler.cs

@@ -191,6 +191,19 @@ static ExecutedRoutedEventHandler OnMoveCaretBoxSelection(CaretMovementType dire
 		internal static void MoveCaret(TextArea textArea, CaretMovementType direction)
 		{
 			double desiredXPos = textArea.Caret.DesiredXPos;
+
+			if (textArea.FlowDirection == FlowDirection.RightToLeft) {
+				if (direction == CaretMovementType.CharLeft) {
+					direction = CaretMovementType.CharRight;
+				} else if (direction == CaretMovementType.CharRight) {
+					direction = CaretMovementType.CharLeft;
+				} else if (direction == CaretMovementType.WordRight) {
+					direction = CaretMovementType.WordLeft;
+				} else if (direction == CaretMovementType.WordLeft) {
+					direction = CaretMovementType.WordRight;
+				}
+			}
+
 			textArea.Caret.Position = GetNewCaretPosition(textArea.TextView, textArea.Caret.Position, direction, textArea.Selection.EnableVirtualSpace, ref desiredXPos);
 			textArea.Caret.DesiredXPos = desiredXPos;
 		}

ICSharpCode.AvalonEdit/Editing/LineNumberMargin.cs

@@ -36,6 +36,17 @@ namespace ICSharpCode.AvalonEdit.Editing
 	/// </summary>
 	public class LineNumberMargin : AbstractMargin, IWeakEventListener
 	{
+		/// <summary>
+		/// Creates a new instance of a LineNumberMargin
+		/// </summary>
+		public LineNumberMargin()
+			:base()
+		{
+			// override Property Value Inheritance, and always render
+			// the line number margin left-to-right
+			FlowDirection = FlowDirection.LeftToRight;
+		}
+
 		static LineNumberMargin()
 		{
 			DefaultStyleKeyProperty.OverrideMetadata(typeof(LineNumberMargin),

ICSharpCode.AvalonEdit/Rendering/TextView.cs

@@ -1054,7 +1054,8 @@ VisualLineTextParagraphProperties CreateParagraphProperties(TextRunProperties de
 			return new VisualLineTextParagraphProperties {
 				defaultTextRunProperties = defaultTextRunProperties,
 				textWrapping = canHorizontallyScroll ? TextWrapping.NoWrap : TextWrapping.Wrap,
-				tabSize = Options.IndentationSize * WideSpaceWidth
+				tabSize = Options.IndentationSize * WideSpaceWidth,
+				flowDirection = FlowDirection
 			};
 		}
 
@@ -1561,7 +1562,10 @@ void CalculateDefaultTextMetrics()
 				using (var line = formatter.FormatLine(
 					new SimpleTextSource("x", textRunProperties),
 					0, 32000,
-					new VisualLineTextParagraphProperties { defaultTextRunProperties = textRunProperties },
+					new VisualLineTextParagraphProperties {
+						defaultTextRunProperties = textRunProperties,
+						flowDirection = FlowDirection
+					},
 					null)) {
 					wideSpaceWidth = Math.Max(1, line.WidthIncludingTrailingWhitespace);
 					defaultBaseline = Math.Max(1, line.Baseline);
@@ -2029,7 +2033,8 @@ protected override void OnPropertyChanged(DependencyPropertyChangedEventArgs e)
 				|| e.Property == Control.FontSizeProperty
 				|| e.Property == Control.FontStretchProperty
 				|| e.Property == Control.FontStyleProperty
-				|| e.Property == Control.FontWeightProperty) {
+				|| e.Property == Control.FontWeightProperty
+				|| e.Property == Control.FlowDirectionProperty) {
 				// changing font properties requires recreating cached elements
 				RecreateCachedElements();
 				// and we need to re-measure the font metrics:

ICSharpCode.AvalonEdit/Rendering/VisualLine.cs

@@ -733,7 +733,7 @@ internal VisualLineDrawingVisual Render()
 		{
 			Debug.Assert(phase == LifetimePhase.Live);
 			if (visual == null)
-				visual = new VisualLineDrawingVisual(this);
+				visual = new VisualLineDrawingVisual(this, textView.FlowDirection);
 			return visual;
 		}
 	}
@@ -744,13 +744,18 @@ sealed class VisualLineDrawingVisual : DrawingVisual
 		public readonly double Height;
 		internal bool IsAdded;
 
-		public VisualLineDrawingVisual(VisualLine visualLine)
+		public VisualLineDrawingVisual(VisualLine visualLine, FlowDirection flow)
 		{
 			this.VisualLine = visualLine;
 			var drawingContext = RenderOpen();
 			double pos = 0;
 			foreach (TextLine textLine in visualLine.TextLines) {
+				if (flow == FlowDirection.LeftToRight) {
 				textLine.Draw(drawingContext, new Point(0, pos), InvertAxes.None);
+				} else  {
+					// Invert Axis for RightToLeft (Arabic language) support
+					textLine.Draw(drawingContext, new Point(0, pos), InvertAxes.Horizontal);
+				}
 				pos += textLine.Height;
 			}
 			this.Height = pos;

ICSharpCode.AvalonEdit/Rendering/VisualLineTextParagraphProperties.cs

@@ -28,12 +28,12 @@ sealed class VisualLineTextParagraphProperties : TextParagraphProperties
 		internal double tabSize;
 		internal double indent;
 		internal bool firstLineInParagraph;
-
+		internal FlowDirection flowDirection;
 		public override double DefaultIncrementalTab {
 			get { return tabSize; }
 		}
 
-		public override FlowDirection FlowDirection { get { return FlowDirection.LeftToRight; } }
+		public override FlowDirection FlowDirection { get { return flowDirection; } }
 		public override TextAlignment TextAlignment { get { return TextAlignment.Left; } }
 		public override double LineHeight { get { return double.NaN; } }
 		public override bool FirstLineInParagraph { get { return firstLineInParagraph; } }

ICSharpCode.AvalonEdit/TextEditor.xaml

@@ -5,8 +5,6 @@
 	<Style TargetType="{x:Type AvalonEdit:TextEditor}">
 		<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.WindowTextBrushKey}}" />
 		<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}" />
-		<Setter Property="FlowDirection" Value="LeftToRight"/>
-		<!-- AvalonEdit does not support RTL, so ensure we use LTR by default -->
 		<Setter Property="Template">
 			<Setter.Value>
 				<ControlTemplate TargetType="{x:Type AvalonEdit:TextEditor}">