Add support for moving the cursor

src/Spectre.Console/Internal/Backends/Ansi/AnsiBackend.cs

@@ -0,0 +1,82 @@
+using System;
+using System.IO;
+using System.Text;
+using Spectre.Console.Rendering;
+
+namespace Spectre.Console.Internal
+{
+    internal sealed class AnsiBackend : IAnsiConsole
+    {
+        private readonly TextWriter _out;
+        private readonly AnsiBuilder _ansiBuilder;
+        private readonly AnsiCursor _cursor;
+
+        public Capabilities Capabilities { get; }
+        public Encoding Encoding { get; }
+        public IAnsiConsoleCursor Cursor => _cursor;
+
+        public int Width
+        {
+            get
+            {
+                if (_out.IsStandardOut())
+                {
+                    return ConsoleHelper.GetSafeBufferWidth(Constants.DefaultBufferWidth);
+                }
+
+                return Constants.DefaultBufferWidth;
+            }
+        }
+
+        public int Height
+        {
+            get
+            {
+                if (_out.IsStandardOut())
+                {
+                    return ConsoleHelper.GetSafeBufferHeight(Constants.DefaultBufferHeight);
+                }
+
+                return Constants.DefaultBufferHeight;
+            }
+        }
+
+        public AnsiBackend(TextWriter @out, Capabilities capabilities, ILinkIdentityGenerator? linkHasher)
+        {
+            _out = @out ?? throw new ArgumentNullException(nameof(@out));
+
+            Capabilities = capabilities ?? throw new ArgumentNullException(nameof(capabilities));
+            Encoding = _out.IsStandardOut() ? System.Console.OutputEncoding : Encoding.UTF8;
+
+            _ansiBuilder = new AnsiBuilder(Capabilities, linkHasher);
+            _cursor = new AnsiCursor(this);
+        }
+
+        public void Clear(bool home)
+        {
+            Write(Segment.Control("\u001b[2J"));
+
+            if (home)
+            {
+                Cursor.SetPosition(0, 0);
+            }
+        }
+
+        public void Write(Segment segment)
+        {
+            var parts = segment.Text.NormalizeLineEndings().Split(new[] { '\n' });
+            foreach (var (_, _, last, part) in parts.Enumerate())
+            {
+                if (!string.IsNullOrEmpty(part))
+                {
+                    _out.Write(_ansiBuilder.GetAnsi(part, segment.Style));
+                }
+
+                if (!last)
+                {
+                    _out.Write(Environment.NewLine);
+                }
+            }
+        }
+    }
+}

src/Spectre.Console/Internal/Backends/Ansi/AnsiCursor.cs

@@ -0,0 +1,56 @@
+using System;
+using Spectre.Console.Rendering;
+
+namespace Spectre.Console.Internal
+{
+    internal sealed class AnsiCursor : IAnsiConsoleCursor
+    {
+        private readonly AnsiBackend _renderer;
+
+        public AnsiCursor(AnsiBackend renderer)
+        {
+            _renderer = renderer ?? throw new ArgumentNullException(nameof(renderer));
+        }
+
+        public void Show(bool show)
+        {
+            if (show)
+            {
+                _renderer.Write(Segment.Control("\u001b[?25h"));
+            }
+            else
+            {
+                _renderer.Write(Segment.Control("\u001b[?25l"));
+            }
+        }
+
+        public void Move(CursorDirection direction, int steps)
+        {
+            if (steps == 0)
+            {
+                return;
+            }
+
+            switch (direction)
+            {
+                case CursorDirection.Up:
+                    _renderer.Write(Segment.Control($"\u001b[{steps}A"));
+                    break;
+                case CursorDirection.Down:
+                    _renderer.Write(Segment.Control($"\u001b[{steps}B"));
+                    break;
+                case CursorDirection.Right:
+                    _renderer.Write(Segment.Control($"\u001b[{steps}C"));
+                    break;
+                case CursorDirection.Left:
+                    _renderer.Write(Segment.Control($"\u001b[{steps}D"));
+                    break;
+            }
+        }
+
+        public void SetPosition(int column, int line)
+        {
+            _renderer.Write(Segment.Control($"\u001b[{line};{column}H"));
+        }
+    }
+}