Improve long lines support

src/AvaloniaEdit.Demo/MainWindow.xaml

@@ -3,6 +3,7 @@
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         MinWidth="500"
         MinHeight="300"
+        Width="950"
         Title="AvaloniaEdit Demo"
         x:Class="AvaloniaEdit.Demo.MainWindow"
         Background="#1E1E1E">
@@ -17,6 +18,9 @@
             <ComboBox Name="syntaxModeCombo" />
             <Button Name="changeThemeBtn" Content="Change theme"/>
         </StackPanel>
+        <StackPanel Name="StatusBar" Background="Purple" Height="25" DockPanel.Dock="Bottom" Orientation="Horizontal">
+            <TextBlock Name="StatusText" Text="Ready" Margin="5 0 0 0" VerticalAlignment="Center" FontSize="12"/>
+        </StackPanel>
         <AvalonEdit:TextEditor Name="Editor"
                                FontFamily="Consolas,Menlo,Monospace"
                                Margin="30"

src/AvaloniaEdit.Demo/MainWindow.xaml.cs

@@ -34,6 +34,7 @@ public class MainWindow : Window
         private Button _clearControlBtn;
         private Button _changeThemeBtn;
         private ComboBox _syntaxModeCombo;
+        private TextBlock _statusTextBlock;
         private ElementGenerator _generator = new ElementGenerator();
         private int _currentTheme = (int)ThemeName.DarkPlus;
 
@@ -57,7 +58,9 @@ public MainWindow()
             _textEditor.TextArea.TextEntered += textEditor_TextArea_TextEntered;
             _textEditor.TextArea.TextEntering += textEditor_TextArea_TextEntering;
             _textEditor.TextArea.IndentationStrategy = new Indentation.CSharp.CSharpIndentationStrategy();
+            _textEditor.TextArea.Caret.PositionChanged += Caret_PositionChanged;
             _textEditor.TextArea.RightClickMovesCaret = true;
+
             _addControlBtn = this.FindControl<Button>("addControlBtn");
             _addControlBtn.Click += _addControlBtn_Click;
 
@@ -85,6 +88,8 @@ public MainWindow()
             _textEditor.Document = new TextDocument(ResourceLoader.LoadSampleFile(scopeName));
             _textMateInstallation.SetGrammarByLanguageId(csharpLanguage.Id);
 
+            _statusTextBlock = this.Find<TextBlock>("StatusText");
+
             this.AddHandler(PointerWheelChangedEvent, (o, i) =>
             {
                 if (i.KeyModifiers != KeyModifiers.Control) return;
@@ -93,6 +98,11 @@ public MainWindow()
             }, RoutingStrategies.Bubble, true);
         }
 
+        private void Caret_PositionChanged(object sender, EventArgs e)
+        {
+            _statusTextBlock.Text = String.Format("Line {0} Column {1}", _textEditor.TextArea.Caret.Line, _textEditor.TextArea.Caret.Column);
+        }
+
         protected override void OnClosed(EventArgs e)
         {
             base.OnClosed(e);

src/AvaloniaEdit.TextMate/AvaloniaEdit.TextMate.csproj

@@ -19,7 +19,7 @@
 
   <ItemGroup>
     <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
-    <PackageReference Include="TextMateSharp" Version="1.0.13" />
+    <PackageReference Include="TextMateSharp" Version="1.0.14" />
   </ItemGroup>
 
 </Project>

src/AvaloniaEdit/Rendering/VisualLine.cs

@@ -37,6 +37,8 @@ namespace AvaloniaEdit.Rendering
     /// </summary>
     public sealed class VisualLine
     {
+        public const int LENGTH_LIMIT = 3000;
+
         private enum LifetimePhase : byte
         {
             Generating,
@@ -155,6 +157,7 @@ internal void ConstructVisualElements(ITextRunConstructionContext context, Visua
         private void PerformVisualElementConstruction(VisualLineElementGenerator[] generators)
         {
             var document = Document;
+            var lineLength = FirstDocumentLine.Length;
             var offset = FirstDocumentLine.Offset;
             var currentLineEnd = offset + FirstDocumentLine.Length;
             LastDocumentLine = FirstDocumentLine;
@@ -164,7 +167,7 @@ private void PerformVisualElementConstruction(VisualLineElementGenerator[] gener
                 var textPieceEndOffset = currentLineEnd;
                 foreach (var g in generators)
                 {
-                    g.CachedInterest = g.GetFirstInterestedOffset(offset + askInterestOffset);
+                    g.CachedInterest = (lineLength > LENGTH_LIMIT) ? -1: g.GetFirstInterestedOffset(offset + askInterestOffset);
                     if (g.CachedInterest != -1)
                     {
                         if (g.CachedInterest < offset)
@@ -179,7 +182,21 @@ private void PerformVisualElementConstruction(VisualLineElementGenerator[] gener
                 if (textPieceEndOffset > offset)
                 {
                     var textPieceLength = textPieceEndOffset - offset;
-                    _elements.Add(new VisualLineText(this, textPieceLength));
+                    int remaining = textPieceLength;
+                    while (true)
+                    {
+                        if (remaining > LENGTH_LIMIT)
+                        {
+                            // split in chunks of LENGTH_LIMIT
+                            _elements.Add(new VisualLineText(this, LENGTH_LIMIT));
+                            remaining -= LENGTH_LIMIT;
+                        }
+                        else
+                        {
+                            _elements.Add(new VisualLineText(this, remaining));
+                            break;
+                        }
+                    }
                     offset = textPieceEndOffset;
                 }
                 // If no elements constructed / only zero-length elements constructed:

src/AvaloniaEdit/Text/TextLineImpl.cs

@@ -9,8 +9,6 @@ namespace AvaloniaEdit.Text
 {
     internal sealed class TextLineImpl : TextLine
     {
-        private const int MaxCharactersPerLine = 10000;
-
         private readonly TextLineRun[] _runs;
 
         public override int FirstIndex { get; }
@@ -49,11 +47,6 @@ internal static TextLineImpl Create(TextParagraphProperties paragraphProperties,
                 visibleLength += AddRunReturnVisibleLength(runs, prevRun);
             }
 
-            if (visibleLength >= MaxCharactersPerLine)
-            {
-                throw new NotSupportedException("Too many characters per line");
-            }
-
             while (true)
             {
                 visibleLength += AddRunReturnVisibleLength(runs, run);

src/AvaloniaEdit/Text/TextLineRun.cs

@@ -1,8 +1,12 @@
 using System;
+using System.Linq;
+
 using Avalonia;
 using Avalonia.Media;
 using Avalonia.Media.TextFormatting;
 
+using AvaloniaEdit.Rendering;
+
 namespace AvaloniaEdit.Text
 {
     internal sealed class TextLineRun
@@ -11,8 +15,7 @@ internal sealed class TextLineRun
 
         private FormattedText _formattedText;
         private Size _formattedTextSize;
-        private double[] _glyphWidths;
-
+        private GlyphWidths _glyphWidths;
         public StringRange StringRange { get; private set; }
 
         public int Length { get; set; }
@@ -109,7 +112,10 @@ private static TextLineRun Create(TextSource textSource, StringRange stringRange
                 return new TextLineRun(textRun.Length, textRun)
                 {
                     IsEmbedded = true,
-                    _glyphWidths = new double[] { width },
+                    _glyphWidths = new GlyphWidths(
+                        stringRange,
+                        textRun.Properties.Typeface.GlyphTypeface,
+                        textRun.Properties.FontSize),
                     // Embedded objects must propagate their width to the container.
                     // Otherwise text runs after the embedded object are drawn at the same x position.
                     Width = width
@@ -162,7 +168,10 @@ private static TextLineRun CreateRunForTab(TextRun textRun)
                 Width = 40
             };
 
-            run.SetGlyphWidths();
+            run._glyphWidths = new GlyphWidths(
+                run.StringRange,
+                run.Typeface.GlyphTypeface,
+                run.FontSize);
 
             return run;
         }
@@ -192,7 +201,10 @@ internal static TextLineRun CreateRunForText(StringRange stringRange, TextRun te
 
             run.Width = size.Width;
 
-            run.SetGlyphWidths();
+            run._glyphWidths = new GlyphWidths(
+                run.StringRange,
+                run.Typeface.GlyphTypeface,
+                run.FontSize);
 
             return run;
         }
@@ -203,27 +215,6 @@ private TextLineRun(int length, TextRun textRun)
             TextRun = textRun;
         }
 
-        private void SetGlyphWidths()
-        {
-            var result = new double[StringRange.Length];
-
-            for (var i = 0; i < StringRange.Length; i++)
-            {
-                // TODO: is there a better way of getting glyph metrics?
-                var tf = Typeface;
-                var size = new FormattedText
-                {
-                    Text = StringRange[i].ToString(),
-                    Typeface = new Typeface(tf.FontFamily, tf.Style, tf.Weight),
-                    FontSize = FontSize
-                }.Bounds.Size;
-
-                result[i] = size.Width;
-            }
-
-            _glyphWidths = result;
-        }
-
         public void Draw(DrawingContext drawingContext, double x, double y)
         {
             if (IsEmbedded)
@@ -290,7 +281,7 @@ public bool UpdateTrailingInfo(TrailingInfo trailing)
             {
                 while (index > 0 && IsSpace(StringRange[index - 1]))
                 {
-                    trailing.SpaceWidth += _glyphWidths[index - 1];
+                    trailing.SpaceWidth += _glyphWidths.GetAt(index - 1);
                     index--;
                     trailing.Count++;
                 }
@@ -313,7 +304,7 @@ public double GetDistanceFromCharacter(int index)
                 double distance = 0;
                 for (var i = 0; i < index; i++)
                 {
-                    distance += _glyphWidths[i];
+                    distance += _glyphWidths.GetAt(i);
                 }
 
                 return distance;
@@ -332,7 +323,7 @@ public double GetDistanceFromCharacter(int index)
             double width = 0;
             for (; index < Length; index++)
             {
-                width = IsTab ? Width / Length : _glyphWidths[index];
+                width = IsTab ? Width / Length : _glyphWidths.GetAt(index);
                 if (distance < width)
                 {
                     break;
@@ -350,5 +341,55 @@ private static bool IsSpace(char ch)
         {
             return ch == ' ' || ch == '\u00a0';
         }
+
+        class GlyphWidths
+        {
+            private const double NOT_CALCULATED_YET = -1;
+            private double[] _glyphWidths;
+            private GlyphTypeface _typeFace;
+            private StringRange _range;
+            private double _scale;
+
+            internal GlyphWidths(StringRange range, GlyphTypeface typeFace, double fontSize)
+            {
+                _range = range;
+                _typeFace = typeFace;
+                _scale = fontSize / _typeFace.DesignEmHeight;
+
+                InitGlyphWidths();
+            }
+
+            internal double GetAt(int index)
+            {
+                if (_glyphWidths[index] == NOT_CALCULATED_YET)
+                    _glyphWidths[index] = MeasureGlyphAt(index);
+
+                return _glyphWidths[index];
+            }
+
+            double MeasureGlyphAt(int index)
+            {
+                return _typeFace.GetGlyphAdvance(
+                    _typeFace.GetGlyph(_range[index])) * _scale;
+            }
+
+            void InitGlyphWidths()
+            {
+                int capacity = _range.Length;
+
+                bool useCheapGlyphMeasurement = 
+                    capacity >= VisualLine.LENGTH_LIMIT && 
+                    _typeFace.IsFixedPitch;
+
+                if (useCheapGlyphMeasurement)
+                {
+                    double size = MeasureGlyphAt(0);
+                    _glyphWidths = Enumerable.Repeat<double>(size, capacity).ToArray();
+                    return;
+                }
+
+                _glyphWidths = Enumerable.Repeat<double>(NOT_CALCULATED_YET, capacity).ToArray();
+            }
+        }
     }
 }