add controls for cursor show/blink

src/ConsoleBuffer/Buffer.cs

@@ -1,4 +1,4 @@
-namespace ConsoleBuffer
+namespace ConsoleBuffer
 {
     using System;
     using System.Collections.Generic;
@@ -15,22 +15,22 @@ public sealed class Buffer : INotifyPropertyChanged
         private short cursorX;
         private short cursorY;
         private int currentChar;
+        /// <summary>
+        /// we store X/Y as 0-offset indexes for convenience. escape codes will pass these around as 1-offset (top left is 1,1)
+        /// and we'll translate that nonsense where we have to.
+        /// </summary>
         public (short X, short Y) CursorPosition => (this.cursorX, this.cursorY);
         public bool CursorVisible { get; private set; }
         public bool CursorBlink { get; private set; }
 
-        private short bufferTopVisibleLine
-        {
-            get
-            {
-                return (short)Math.Max(0, this.lines.Size - this.Height);
-            }
-        }
-        private short currentLine
+        private int topVisibleLine;
+        private int bottomVisibleLine;
+
+        private int CurrentLine
         {
             get
             {
-                return (short)(this.bufferTopVisibleLine + this.CursorPosition.Y);
+                return this.topVisibleLine + this.CursorPosition.Y;
             }
         }
 
@@ -44,7 +44,14 @@ public Buffer(short width, short height)
             this.Width = width;
             this.Height = height;
             this.CursorVisible = this.CursorBlink = true;
-            this.lines.PushBack(new Line());
+            this.cursorX = this.cursorY = 0;
+
+            for (var y = 0; y < this.Height; ++y)
+            {
+                this.lines.PushBack(new Line());
+            }
+            this.topVisibleLine = 0;
+            this.bottomVisibleLine = this.Height - 1;
         }
 
         public void Append(byte[] bytes, int length)
@@ -58,8 +65,20 @@ public void Append(byte[] bytes, int length)
                     switch (this.parser.Append(this.currentChar))
                     {
                     case ParserAppendResult.Render:
-                        this.lines[this.currentLine].Set(this.cursorX, new Character { Glyph = this.currentChar });
-                        this.cursorX = (short)Math.Min(this.Width - 1, this.cursorX + 1);
+                        this.lines[this.CurrentLine].Set(this.cursorX, new Character { Glyph = this.currentChar });
+                        ++this.cursorX;
+                        if (this.cursorX == this.Width)
+                        {
+                            this.cursorX = 0;
+                            if (this.cursorY == this.Height - 1)
+                            {
+                                this.ScrollDown();
+                            }
+                            else
+                            {
+                                ++this.cursorY;
+                            }
+                        }
                         break;
                     case ParserAppendResult.Complete:
                         this.ExecuteParserCommand();
@@ -102,10 +121,13 @@ private void ExecuteParserCommand()
                     this.OnPropertyChanged("Title");
                 }
                 break;
+            case Commands.ControlSequence csiCommand:
+                this.HandleControlSequence(csiCommand);
+                break;
             case Commands.Unsupported unsupported:
                 break;
             default:
-                throw new InvalidOperationException("Unknown command type passed.");
+                throw new InvalidOperationException($"Unknown command type passed: {this.parser.Command?.GetType()}.");
             }
         }
 
@@ -127,9 +149,9 @@ private void HandleControlCharacter(Commands.ControlCharacter.ControlCode code)
                 break;
             case Commands.ControlCharacter.ControlCode.FF: // NB: could clear screen with this if we were so inclined. apparently xterm treats this as LF though, let's emulate.
             case Commands.ControlCharacter.ControlCode.LF:
-                if (this.currentLine == this.lines.Size - 1)
+                if (this.CurrentLine == this.bottomVisibleLine)
                 {
-                    this.lines.PushBack(new Line());
+                    this.ScrollDown();
                 }
 
                 this.cursorY = (short)Math.Min(this.Height - 1, this.cursorY + 1);
@@ -145,6 +167,74 @@ private void HandleControlCharacter(Commands.ControlCharacter.ControlCode code)
             }
         }
 
+        private void HandleControlSequence(Commands.ControlSequence cmd)
+        {
+            switch (cmd)
+            {
+            case Commands.EraseInDisplay eid:
+                switch (eid.Direction)
+                {
+                case Commands.EraseInDisplay.Parameter.All:
+                    for (var y = this.topVisibleLine; y <= this.bottomVisibleLine; ++y)
+                    {
+                        this.lines[y].Clear();
+                    }
+                    break;
+                case Commands.EraseInDisplay.Parameter.Above:
+                    for (var y = this.topVisibleLine; y < this.CurrentLine; ++y)
+                    {
+                        this.lines[y].Clear();
+                    }
+                    break;
+                case Commands.EraseInDisplay.Parameter.Below:
+                    for (var y = this.CurrentLine; y < this.bottomVisibleLine; ++y)
+                    {
+                        this.lines[y].Clear();
+                    }
+                    break;
+                }
+                break;
+            case Commands.SetMode sm:
+                switch (sm.Setting)
+                {
+                case Commands.SetMode.Parameter.CursorBlink:
+                    this.CursorBlink = sm.Set;
+                    break;
+                case Commands.SetMode.Parameter.CursorShow:
+                    this.CursorVisible = sm.Set;
+                    break;
+                }
+                break;
+            default:
+                throw new InvalidOperationException($"Unknown CSI command type {cmd.GetType()}.");
+            }
+        }
+
+        /// <summary>
+        /// Scroll the visible buffer down, adding new lines if needed.
+        /// If we're at the bottom of the buffer we will replace lines from the top with new, blank lines.
+        /// </summary>
+        private void ScrollDown(int lines = 1)
+        {
+            while (lines > 0)
+            {
+                --lines;
+                if (this.bottomVisibleLine == this.lines.Capacity - 1)
+                {
+                    this.lines.PushBack(new Line()); // will force an old line from the buffer;
+                }
+                else
+                {
+                    ++this.topVisibleLine;
+                    ++this.bottomVisibleLine;
+                    if (this.lines.Size <= this.bottomVisibleLine)
+                    {
+                        this.lines.PushBack(new Line());
+                    }
+                }
+            }
+        }
+
         /// <summary>
         /// Render character-by-character onto the specified target.
         /// </summary>
@@ -154,7 +244,7 @@ public void Render(IRenderTarget target)
             {
                 for (var y = 0; y < this.Height; ++y)
                 {
-                    var renderLine = this.bufferTopVisibleLine + y;
+                    var renderLine = this.topVisibleLine + y;
                     var line = renderLine < this.lines.Size ? this.lines[renderLine] : Line.Empty;
                     short x = 0;
                     foreach (var c in line)

src/ConsoleBuffer/Commands/ControlSequence.cs

@@ -9,20 +9,26 @@ public static Base Create(char command, string bufferData)
         {
             switch (command)
             {
+            case 'h':
+            case 'l':
+                return new SetMode(bufferData, command == 'h');
             case 'J':
-                var cmd = new EraseInDisplay(bufferData);
-                if (!cmd.IsExtended) // currently no support for selective erase in display
-                    return cmd;
-                break;
+                return new EraseInDisplay(bufferData);
             }
             return new Unsupported($"^[[{bufferData}{command}");
         }
 
-        protected bool IsExtended { get; private set; }
+        public bool IsExtended { get; private set; }
         protected IList<string> Parameters { get; private set; }
         protected ControlSequence(string bufferData) : base(bufferData) { }
         protected override void Parse(string bufferData)
         {
+            if (bufferData.Length == 0)
+            {
+                this.Parameters = Array.Empty<string>();
+                return;
+            }
+
             var startIndex = 0;
             if (bufferData[0] == '?')
             {

src/ConsoleBuffer/Commands/EraseInDisplay.cs

@@ -1,7 +1,36 @@
+using System;
+
 namespace ConsoleBuffer.Commands
 {
     public sealed class EraseInDisplay : ControlSequence
     {
-        public EraseInDisplay(string bufferData) : base(bufferData) { }
+        public enum Parameter
+        {
+            Below = 0,
+            Above,
+            All,
+            // xterm supports '3' for saved lines.
+            Unknown,
+        }
+
+        public Parameter Direction { get; private set; }
+
+        public EraseInDisplay(string bufferData) : base(bufferData)
+        {
+            this.Direction = Parameter.Unknown;
+            if (this.IsExtended)
+            {
+                return; // extended means selective erase which we don't support.
+            }
+            if (this.Parameters.Count == 0)
+            {
+                this.Direction = Parameter.Below;
+            }
+            if (this.Parameters.Count == 1 && uint.TryParse(this.Parameters[0], out var param))
+            {
+                param = Math.Min((uint)Parameter.Unknown, param);
+                this.Direction = (Parameter)param;
+            }
+        }
     }
 }

src/ConsoleBuffer/Commands/SetMode.cs

@@ -0,0 +1,42 @@
+namespace ConsoleBuffer.Commands
+{
+    public sealed class SetMode : ControlSequence
+    {
+        /// <summary>
+        /// True if the command was to set (not reset) the parameter.
+        /// </summary>
+        public bool Set { get; private set; }
+        public enum Parameter
+        {
+            CursorShow = 0,
+            CursorBlink,
+            Unknown,
+        }
+
+        public Parameter Setting { get; private set; }
+
+        public SetMode(string bufferData, bool set) : base(bufferData)
+        {
+            this.Set = set;
+            this.Setting = Parameter.Unknown;
+
+            if (!this.IsExtended)
+            {
+                return;
+            }
+
+            if (this.Parameters.Count == 1)
+            {
+                switch (this.Parameters[0])
+                {
+                case "12":
+                    this.Setting = Parameter.CursorBlink;
+                    break;
+                case "25":
+                    this.Setting = Parameter.CursorShow;
+                    break;
+                }
+            }
+        }
+    }
+}

src/ConsoleBuffer/Line.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
@@ -28,6 +28,11 @@ public void Set(int pos, Character ch)
             this.chars[pos] = ch;
         }
 
+        public void Clear()
+        {
+            this.chars.Clear();
+        }
+
         private void Extend(int pos)
         {
             // XXX: not efficient.
@@ -37,14 +42,15 @@ private void Extend(int pos)
             }
         }
 
+
         public IEnumerator<Character> GetEnumerator()
         {
-            return chars.GetEnumerator();
+            return this.chars.GetEnumerator();
         }
 
         IEnumerator IEnumerable.GetEnumerator()
         {
-            return chars.GetEnumerator();
+            return this.chars.GetEnumerator();
         }
 
         public override string ToString()

src/condo/Screen.cs

@@ -1,14 +1,12 @@
-namespace condo
+namespace condo
 {
     using System;
     using System.Collections.Generic;
     using System.ComponentModel;
     using System.Diagnostics;
-    using System.Threading;
     using System.Windows;
     using System.Windows.Input;
     using System.Windows.Media;
-    using System.Windows.Threading;
     using ConsoleBuffer;
 
     public sealed class Screen : FrameworkElement, IRenderTarget
@@ -24,6 +22,7 @@ public sealed class Screen : FrameworkElement, IRenderTarget
         private readonly Rect cellRectangle;
         private int horizontalCells, verticalCells;
         private Character[,] characters;
+        bool cursorInverted;
         private volatile int shouldRedraw;
 
         private static readonly TimeSpan MaxRedrawFrequency = TimeSpan.FromMilliseconds(10);
@@ -63,7 +62,6 @@ public Screen(ConsoleWrapper console)
             this.Resize();
         }
 
-        bool cursorBlunk;
         private void RenderFrame(object sender, EventArgs e)
         {
             if (this.redrawWatch.Elapsed >= MaxRedrawFrequency && this.shouldRedraw != 0)
@@ -74,12 +72,15 @@ private void RenderFrame(object sender, EventArgs e)
                 this.redrawWatch.Restart();
             }
 
-            if (this.cursorBlinkWatch.Elapsed >= BlinkFrequency)
+            if (this.Console.Buffer.CursorVisible)
             {
-                (var x, var y) = this.Console.Buffer.CursorPosition;
-                this.SetCellCharacter(x, y, (char)this.characters[x, y].Glyph, this.cursorBlunk);
-                this.cursorBlunk = !this.cursorBlunk;
-                this.cursorBlinkWatch.Restart();
+                if (this.cursorBlinkWatch.Elapsed >= BlinkFrequency)
+                {
+                    this.cursorInverted = this.Console.Buffer.CursorBlink ? !this.cursorInverted : true;
+                    (var x, var y) = this.Console.Buffer.CursorPosition;
+                    this.SetCellCharacter(x, y, (char)this.characters[x, y].Glyph, this.cursorInverted);
+                    this.cursorBlinkWatch.Restart();
+                }
             }
         }