Add support for Surrogate Unicode sequences

src/Consolonia.Core/Consolonia.Core.csproj

@@ -6,8 +6,8 @@
         <PackageReference Include="Avalonia.FreeDesktop" Version="$(AvaloniaVersion)" />
         <PackageReference Include="Avalonia.Skia" Version="$(AvaloniaVersion)" />
         <PackageReference Include="Avalonia.Controls.DataGrid" Version="$(AvaloniaVersion)" />
-        <PackageReference Include="NullLib.ConsoleEx" Version="1.0.4.4" />
         <PackageReference Include="SkiaSharp.NativeAssets.Linux.NoDependencies" Version="2.88.8" />
+        <PackageReference Include="Unicode.net" Version="2.0.0" />
     </ItemGroup>
 
 </Project>

src/Consolonia.Core/Drawing/ConsoleBrush.cs

@@ -1,11 +1,13 @@
 using System;
+using System.Diagnostics;
 using Avalonia;
 using Avalonia.Media;
 using Consolonia.Core.Drawing.PixelBufferImplementation;
 using Consolonia.Core.Infrastructure;
 
 namespace Consolonia.Core.Drawing
 {
+    [DebuggerDisplay("{Color} [{Mode}]")]
     public class ConsoleBrush : AvaloniaObject, IImmutableBrush
     {
         public static readonly StyledProperty<Color> ColorProperty =

src/Consolonia.Core/Drawing/PixelBufferImplementation/DrawingBoxSymbol.cs

@@ -1,10 +1,13 @@
 using System;
+using System.Diagnostics;
+using System.Text;
 
 namespace Consolonia.Core.Drawing.PixelBufferImplementation
 {
     /// <summary>
     ///     https://en.wikipedia.org/wiki/Box-drawing_character
     /// </summary>
+    [DebuggerDisplay("DrawingBox {Text}")]
     public struct DrawingBoxSymbol : ISymbol
     {
         // all 0bXXXX_0000 are special values
@@ -18,10 +21,14 @@ public DrawingBoxSymbol(byte upRightDownLeft)
 
         private byte _upRightDownLeft;
 
+        public string Text => GetBoxSymbol().ToString();
+
+        public ushort Width { get; } = 1;
+
         /// <summary>
         ///     https://en.wikipedia.org/wiki/Code_page_437
         /// </summary>
-        char ISymbol.GetCharacter()
+        private char GetBoxSymbol()
         {
             //DOS linedraw characters are not ordered in any programmatic manner, and calculating a particular character shape needs to use a look-up table. from https://en.wikipedia.org/wiki/Box-drawing_character
 
@@ -49,46 +56,46 @@ char ISymbol.GetCharacter()
                     return horizontal ? '╪' : '╫';
 
                 default:
-                {
-                    return _upRightDownLeft switch
                     {
-                        EmptySymbol => char.MinValue,
-                        BoldSymbol => '█',
-                        0b0000_1001 => '┘',
-                        0b1000_1001 => '╜',
-                        0b0001_1001 => '╛',
-                        0b1001_1001 => '╝',
-                        0b0000_0011 => '┐',
-                        0b0010_0011 => '╖',
-                        0b0001_0011 => '╕',
-                        0b0011_0011 => '╗',
-                        0b0000_0110 => '┌',
-                        0b0100_0110 => '╒',
-                        0b0010_0110 => '╓',
-                        0b0110_0110 => '╔',
-                        0b0000_1100 => '└',
-                        0b0100_1100 => '╘',
-                        0b1000_1100 => '╙',
-                        0b1100_1100 => '╚',
-                        0b0000_1110 => '├',
-                        0b1000_1110 or 0b0010_1110 or 0b1010_1110 => '╟',
-                        0b0100_1110 => '╞',
-                        0b1100_1110 or 0b0110_1110 or 0b1110_1110 => '╠',
-                        0b0000_1011 => '┤',
-                        0b1000_1011 or 0b0010_1011 or 0b1010_1011 => '╢',
-                        0b0001_1011 => '╡',
-                        0b1001_1011 or 0b0011_1011 or 0b1011_1011 => '╣',
-                        0b0000_1101 => '┴',
-                        0b1000_1101 => '╨',
-                        0b0100_1101 or 0b0001_1101 or 0b0101_1101 => '╧',
-                        0b1100_1101 or 0b1001_1101 or 0b1101_1101 => '╩',
-                        0b0000_0111 => '┬',
-                        0b0010_0111 => '╥',
-                        0b0100_0111 or 0b0001_0111 or 0b0101_0111 => '╤',
-                        0b0110_0111 or 0b0011_0111 or 0b0111_0111 => '╦',
-                        _ => throw new InvalidOperationException()
-                    };
-                }
+                        return _upRightDownLeft switch
+                        {
+                            EmptySymbol => char.MinValue,
+                            BoldSymbol => '█',
+                            0b0000_1001 => '┘',
+                            0b1000_1001 => '╜',
+                            0b0001_1001 => '╛',
+                            0b1001_1001 => '╝',
+                            0b0000_0011 => '┐',
+                            0b0010_0011 => '╖',
+                            0b0001_0011 => '╕',
+                            0b0011_0011 => '╗',
+                            0b0000_0110 => '┌',
+                            0b0100_0110 => '╒',
+                            0b0010_0110 => '╓',
+                            0b0110_0110 => '╔',
+                            0b0000_1100 => '└',
+                            0b0100_1100 => '╘',
+                            0b1000_1100 => '╙',
+                            0b1100_1100 => '╚',
+                            0b0000_1110 => '├',
+                            0b1000_1110 or 0b0010_1110 or 0b1010_1110 => '╟',
+                            0b0100_1110 => '╞',
+                            0b1100_1110 or 0b0110_1110 or 0b1110_1110 => '╠',
+                            0b0000_1011 => '┤',
+                            0b1000_1011 or 0b0010_1011 or 0b1010_1011 => '╢',
+                            0b0001_1011 => '╡',
+                            0b1001_1011 or 0b0011_1011 or 0b1011_1011 => '╣',
+                            0b0000_1101 => '┴',
+                            0b1000_1101 => '╨',
+                            0b0100_1101 or 0b0001_1101 or 0b0101_1101 => '╧',
+                            0b1100_1101 or 0b1001_1101 or 0b1101_1101 => '╩',
+                            0b0000_0111 => '┬',
+                            0b0010_0111 => '╥',
+                            0b0100_0111 or 0b0001_0111 or 0b0101_0111 => '╤',
+                            0b0110_0111 or 0b0011_0111 or 0b0111_0111 => '╦',
+                            _ => throw new InvalidOperationException()
+                        };
+                    }
             }
         }
 
@@ -106,22 +113,21 @@ public ISymbol Blend(ref ISymbol symbolAbove)
                 _upRightDownLeft = BoldSymbol;
             else
                 _upRightDownLeft |= drawingBoxSymbol._upRightDownLeft;
-
             return this;
         }
 
-        public static byte UpRightDownLeftFromPattern(byte pattern, LineStyle lineStyle)
+        public static DrawingBoxSymbol UpRightDownLeftFromPattern(byte pattern, LineStyle lineStyle)
         {
-            if (pattern == EmptySymbol) return EmptySymbol;
+            if (pattern == EmptySymbol) return new DrawingBoxSymbol(EmptySymbol);
             switch (lineStyle)
             {
                 case LineStyle.SingleLine:
-                    return pattern;
+                    return new DrawingBoxSymbol(pattern);
                 case LineStyle.Bold:
-                    return BoldSymbol;
+                    return new DrawingBoxSymbol(BoldSymbol);
                 case LineStyle.DoubleLine:
                     byte leftPart = (byte)(pattern << 4);
-                    return (byte)(leftPart | pattern);
+                    return new DrawingBoxSymbol((byte)(leftPart | pattern));
                 default:
                     throw new ArgumentOutOfRangeException(nameof(lineStyle), lineStyle, null);
             }

src/Consolonia.Core/Drawing/PixelBufferImplementation/ISymbol.cs

@@ -1,9 +1,26 @@
+using System.Text;
+
 namespace Consolonia.Core.Drawing.PixelBufferImplementation
 {
     public interface ISymbol
     {
-        char GetCharacter();
+        /// <summary>
+        ///     The text for the symbol (This can be single character or unicode encoding for Emoji's and the like)
+        /// </summary>
+        string Text { get; }
+
+        /// <summary>
+        ///     The number of characters the symbol takes up
+        /// </summary>
+        ushort Width { get; } 
+
         bool IsWhiteSpace();
+
+        /// <summary>
+        ///     Blend 2 symbols together
+        /// </summary>
+        /// <param name="symbolAbove"></param>
+        /// <returns></returns>
         ISymbol Blend(ref ISymbol symbolAbove);
     }
 }

src/Consolonia.Core/Drawing/PixelBufferImplementation/Pixel.cs

@@ -1,11 +1,14 @@
 using System;
+using System.Diagnostics;
+using System.Text;
 using Avalonia.Media;
 
 // ReSharper disable MemberCanBePrivate.Global
 // ReSharper disable UnusedMember.Global
 
 namespace Consolonia.Core.Drawing.PixelBufferImplementation
 {
+    [DebuggerDisplay("'{Foreground.Symbol.Text}' [{Foreground.Color}, {Background.Color}]")]
     public readonly struct Pixel
     {
         public PixelForeground Foreground { get; }
@@ -14,22 +17,6 @@ public readonly struct Pixel
 
         public bool IsCaret { get; }
 
-        public Pixel(bool isCaret) : this(PixelBackgroundMode.Transparent)
-        {
-            IsCaret = isCaret;
-        }
-
-        public Pixel(char character, Color foregroundColor, FontStyle style = FontStyle.Normal,
-            FontWeight weight = FontWeight.Normal) :
-            this(new SimpleSymbol(character), foregroundColor, style, weight)
-        {
-        }
-
-        public Pixel(byte drawingBoxSymbol, Color foregroundColor) : this(
-            new DrawingBoxSymbol(drawingBoxSymbol), foregroundColor)
-        {
-        }
-
         public Pixel(ISymbol symbol, Color foregroundColor, FontStyle style = FontStyle.Normal,
             FontWeight weight = FontWeight.Normal, TextDecorationCollection textDecorations = null) : this(
             new PixelForeground(symbol, weight, style, textDecorations, foregroundColor),
@@ -68,11 +55,17 @@ public Pixel Blend(Pixel pixelAbove)
                 case PixelBackgroundMode.Colored:
                     // merge pixelAbove into this pixel using alpha channel.
                     Color mergedColors = MergeColors(Background.Color, pixelAbove.Background.Color);
-                    return new Pixel(pixelAbove.Foreground,
-                        new PixelBackground(mergedColors));
+                    newForeground = pixelAbove.Foreground;
+                    newBackground = new PixelBackground(mergedColors);
+                    break;
 
                 case PixelBackgroundMode.Transparent:
-                    newForeground = Foreground.Blend(pixelAbove.Foreground);
+                    // if the foreground is transparent, ignore pixelAbove foreground.
+                    newForeground = pixelAbove.Foreground.Color != Colors.Transparent
+                        ? Foreground.Blend(pixelAbove.Foreground)
+                        : Foreground;
+
+                    // background is transparent, ignore pixelAbove background.
                     newBackground = Background;
                     break;
                 case PixelBackgroundMode.Shaded:

src/Consolonia.Core/Drawing/PixelBufferImplementation/PixelBackground.cs

@@ -1,8 +1,10 @@
 using System;
+using System.Diagnostics;
 using Avalonia.Media;
 
 namespace Consolonia.Core.Drawing.PixelBufferImplementation
 {
+    [DebuggerDisplay("[{Color}, {Mode}]")]
     public readonly struct PixelBackground
     {
         public PixelBackground(Color color)

src/Consolonia.Core/Drawing/PixelBufferImplementation/PixelBuffer.cs

@@ -11,12 +11,14 @@ namespace Consolonia.Core.Drawing.PixelBufferImplementation
     public class PixelBuffer : IEnumerable<Pixel>
     {
         private readonly Pixel[,] _buffer;
+        private PixelBufferCoordinate _caretPosition;
 
         public PixelBuffer(ushort width, ushort height)
         {
             Width = width;
             Height = height;
             _buffer = new Pixel[width, height];
+            _caretPosition = new PixelBufferCoordinate(0, 0);
         }
 
         public ushort Width { get; }
@@ -68,6 +70,25 @@ public void Set<TUserObject>(PixelBufferCoordinate point, Func<Pixel, TUserObjec
             this[point] = changeAction(this[point], userObject);
         }
 
+        /// <summary>
+        ///     Clears old pixel caret position and sets new caret position
+        /// </summary>
+        /// <param name="point"></param>
+        public void SetCaretPosition(PixelBufferCoordinate point)
+        {
+            // clear old caret position by merging in IsCaret = false
+            Pixel oldCaretPixel = _buffer[_caretPosition.X, _caretPosition.Y];
+            _buffer[_caretPosition.X, _caretPosition.Y] =
+                new Pixel(oldCaretPixel.Foreground, oldCaretPixel.Background, false);
+
+            _caretPosition = point;
+
+            // set new caret position by merging in IsCaret = true
+            Pixel newCaretPixel = _buffer[_caretPosition.X, _caretPosition.Y];
+            _buffer[_caretPosition.X, _caretPosition.Y] =
+                new Pixel(newCaretPixel.Foreground, newCaretPixel.Background, true);
+        }
+
         public void Foreach(Func<PixelBufferCoordinate, Pixel, Pixel> replaceAction)
         {
             ForeachReadonly((point, oldPixel) =>

src/Consolonia.Core/Drawing/PixelBufferImplementation/PixelForeground.cs

@@ -1,8 +1,10 @@
 using System;
+using System.Diagnostics;
 using Avalonia.Media;
 
 namespace Consolonia.Core.Drawing.PixelBufferImplementation
 {
+    [DebuggerDisplay("'{Symbol.Text}' [{Color}]")]
     public readonly struct PixelForeground
     {
         public PixelForeground(ISymbol symbol, FontWeight weight = FontWeight.Normal,
@@ -38,8 +40,6 @@ public PixelForeground Blend(PixelForeground pixelAboveForeground)
             ISymbol symbolAbove = pixelAboveForeground.Symbol;
             ArgumentNullException.ThrowIfNull(symbolAbove);
 
-            if (symbolAbove.IsWhiteSpace()) return this;
-
             ISymbol newSymbol = Symbol.Blend(ref symbolAbove);
 
             return new PixelForeground(newSymbol, pixelAboveForeground.Weight, pixelAboveForeground.Style,

src/Consolonia.Core/Drawing/PixelBufferImplementation/SimpleSymbol.cs

@@ -1,27 +1,43 @@
+using System;
+using System.Diagnostics;
+using System.Linq;
+using System.Text;
+
 namespace Consolonia.Core.Drawing.PixelBufferImplementation
 {
+    [DebuggerDisplay("'{Text}'")]
     public readonly struct SimpleSymbol : ISymbol
     {
-        public SimpleSymbol(char character)
+        public SimpleSymbol()
         {
-            _character = character;
+            Text = string.Empty;
+            Width = 1;
         }
 
-        private readonly char _character;
+        public SimpleSymbol(char character)
+        {
+            Text = character.ToString();
+            Width = 1;
+        }
 
-        char ISymbol.GetCharacter()
+        public SimpleSymbol(string text, ushort width)
         {
-            return _character;
+            Text = text;
+            Width = width;
         }
 
+        public string Text { get; } = string.Empty;
+
+        public ushort Width { get; }
+
         public bool IsWhiteSpace()
         {
-            return _character == char.MinValue;
+            return string.IsNullOrWhiteSpace(Text);
         }
 
         public ISymbol Blend(ref ISymbol symbolAbove)
         {
-            return symbolAbove;
+            return !String.IsNullOrEmpty(symbolAbove.Text) ? symbolAbove : this;
         }
     }
 }