gui-cs.Terminal.Gui/Terminal.Gui/ConsoleDrivers/NetDriver/NetDriver.cs

#nullable enable
//
// NetDriver.cs: The System.Console-based .NET driver, works on Windows and Unix, but is not particularly efficient.
//

using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.InteropServices;
using static Terminal.Gui.ConsoleDrivers.ConsoleKeyMapping;
using static Terminal.Gui.NetEvents;

namespace Terminal.Gui;

internal class NetDriver : ConsoleDriver
{
    public bool IsWinPlatform { get; private set; }
    public NetWinVTConsole? NetWinConsole { get; private set; }

    public override void Refresh ()
    {
        UpdateScreen ();
        UpdateCursor ();
    }

    public override void Suspend ()
    {
        if (Environment.OSVersion.Platform != PlatformID.Unix)
        {
            return;
        }

        StopReportingMouseMoves ();

        if (!RunningUnitTests)
        {
            Console.ResetColor ();
            Console.Clear ();

            //Disable alternative screen buffer.
            Console.Out.Write (AnsiEscapeSequenceRequestUtils.CSI_RestoreCursorAndRestoreAltBufferWithBackscroll);

            //Set cursor key to cursor.
            Console.Out.Write (AnsiEscapeSequenceRequestUtils.CSI_ShowCursor);

            Platform.Suspend ();

            //Enable alternative screen buffer.
            Console.Out.Write (AnsiEscapeSequenceRequestUtils.CSI_SaveCursorAndActivateAltBufferNoBackscroll);

            SetContentsAsDirty ();
            Refresh ();
        }

        StartReportingMouseMoves ();
    }

    #region Screen and Contents

    public override void UpdateScreen ()
    {
        if (RunningUnitTests
            || _winSizeChanging
            || Console.WindowHeight < 1
            || Contents?.Length != Rows * Cols
            || Rows != Console.WindowHeight)
        {
            return;
        }

        var top = 0;
        var left = 0;
        int rows = Rows;
        int cols = Cols;
        var output = new StringBuilder ();
        Attribute? redrawAttr = null;
        int lastCol = -1;

        CursorVisibility? savedVisibility = _cachedCursorVisibility;
        SetCursorVisibility (CursorVisibility.Invisible);

        for (int row = top; row < rows; row++)
        {
            if (Console.WindowHeight < 1)
            {
                return;
            }

            if (!_dirtyLines! [row])
            {
                continue;
            }

            if (!SetCursorPosition (0, row))
            {
                return;
            }

            _dirtyLines [row] = false;
            output.Clear ();

            for (int col = left; col < cols; col++)
            {
                lastCol = -1;
                var outputWidth = 0;

                for (; col < cols; col++)
                {
                    if (!Contents [row, col].IsDirty)
                    {
                        if (output.Length > 0)
                        {
                            WriteToConsole (output, ref lastCol, row, ref outputWidth);
                        }
                        else if (lastCol == -1)
                        {
                            lastCol = col;
                        }

                        if (lastCol + 1 < cols)
                        {
                            lastCol++;
                        }

                        continue;
                    }

                    if (lastCol == -1)
                    {
                        lastCol = col;
                    }

                    Attribute attr = Contents [row, col].Attribute!.Value;

                    // Performance: Only send the escape sequence if the attribute has changed.
                    if (attr != redrawAttr)
                    {
                        redrawAttr = attr;

                        if (Force16Colors)
                        {
                            output.Append (
                                           AnsiEscapeSequenceRequestUtils.CSI_SetGraphicsRendition (
                                                                                 MapColors (
                                                                                            (ConsoleColor)attr.Background.GetClosestNamedColor16 (),
                                                                                            false
                                                                                           ),
                                                                                 MapColors ((ConsoleColor)attr.Foreground.GetClosestNamedColor16 ())
                                                                                )
                                          );
                        }
                        else
                        {
                            output.Append (
                                           AnsiEscapeSequenceRequestUtils.CSI_SetForegroundColorRGB (
                                                                                  attr.Foreground.R,
                                                                                  attr.Foreground.G,
                                                                                  attr.Foreground.B
                                                                                 )
                                          );

                            output.Append (
                                           AnsiEscapeSequenceRequestUtils.CSI_SetBackgroundColorRGB (
                                                                                  attr.Background.R,
                                                                                  attr.Background.G,
                                                                                  attr.Background.B
                                                                                 )
                                          );
                        }
                    }

                    outputWidth++;
                    Rune rune = Contents [row, col].Rune;
                    output.Append (rune);

                    if (Contents [row, col].CombiningMarks.Count > 0)
                    {
                        // AtlasEngine does not support NON-NORMALIZED combining marks in a way
                        // compatible with the driver architecture. Any CMs (except in the first col)
                        // are correctly combined with the base char, but are ALSO treated as 1 column
                        // width codepoints E.g. `echo "[e`u{0301}`u{0301}]"` will output `[é  ]`.
                        // 
                        // For now, we just ignore the list of CMs.
                        //foreach (var combMark in Contents [row, col].CombiningMarks) {
                        //	output.Append (combMark);
                        //}
                        // WriteToConsole (output, ref lastCol, row, ref outputWidth);
                    }
                    else if (rune.IsSurrogatePair () && rune.GetColumns () < 2)
                    {
                        WriteToConsole (output, ref lastCol, row, ref outputWidth);
                        SetCursorPosition (col - 1, row);
                    }

                    Contents [row, col].IsDirty = false;
                }
            }

            if (output.Length > 0)
            {
                SetCursorPosition (lastCol, row);
                Console.Write (output);
            }

            foreach (SixelToRender s in Application.Sixel)
            {
                if (!string.IsNullOrWhiteSpace (s.SixelData))
                {
                    SetCursorPosition (s.ScreenPosition.X, s.ScreenPosition.Y);
                    Console.Write (s.SixelData);
                }
            }
        }

        SetCursorPosition (0, 0);

        _cachedCursorVisibility = savedVisibility;

        void WriteToConsole (StringBuilder output, ref int lastCol, int row, ref int outputWidth)
        {
            SetCursorPosition (lastCol, row);
            Console.Write (output);
            output.Clear ();
            lastCol += outputWidth;
            outputWidth = 0;
        }
    }

    #endregion Screen and Contents

    #region Init/End/MainLoop

    internal NetMainLoop? _mainLoopDriver;

    internal override MainLoop Init ()
    {
        PlatformID p = Environment.OSVersion.Platform;

        if (p == PlatformID.Win32NT || p == PlatformID.Win32S || p == PlatformID.Win32Windows)
        {
            IsWinPlatform = true;

            try
            {
                NetWinConsole = new ();
            }
            catch (ApplicationException)
            {
                // Likely running as a unit test, or in a non-interactive session.
            }
        }

        if (IsWinPlatform)
        {
            Clipboard = new WindowsClipboard ();
        }
        else if (RuntimeInformation.IsOSPlatform (OSPlatform.OSX))
        {
            Clipboard = new MacOSXClipboard ();
        }
        else
        {
            if (CursesDriver.Is_WSL_Platform ())
            {
                Clipboard = new WSLClipboard ();
            }
            else
            {
                Clipboard = new CursesClipboard ();
            }
        }

        if (!RunningUnitTests)
        {
            Console.TreatControlCAsInput = true;

            Cols = Console.WindowWidth;
            Rows = Console.WindowHeight;

            //Enable alternative screen buffer.
            Console.Out.Write (AnsiEscapeSequenceRequestUtils.CSI_SaveCursorAndActivateAltBufferNoBackscroll);

            //Set cursor key to application.
            Console.Out.Write (AnsiEscapeSequenceRequestUtils.CSI_HideCursor);
        }
        else
        {
            // We are being run in an environment that does not support a console
            // such as a unit test, or a pipe.
            Cols = 80;
            Rows = 24;
        }

        ResizeScreen ();
        ClearContents ();
        CurrentAttribute = new (Color.White, Color.Black);

        StartReportingMouseMoves ();

        _mainLoopDriver = new (this);
        _mainLoopDriver.ProcessInput = ProcessInput;

        return new (_mainLoopDriver);
    }

    private void ProcessInput (InputResult inputEvent)
    {
        switch (inputEvent.EventType)
        {
            case EventType.Key:
                ConsoleKeyInfo consoleKeyInfo = inputEvent.ConsoleKeyInfo;

                //if (consoleKeyInfo.Key == ConsoleKey.Packet) {
                //	consoleKeyInfo = FromVKPacketToKConsoleKeyInfo (consoleKeyInfo);
                //}

                //Debug.WriteLine ($"event: {inputEvent}");

                KeyCode map = AnsiEscapeSequenceRequestUtils.MapKey (consoleKeyInfo);

                if (map == KeyCode.Null)
                {
                    break;
                }

                OnKeyDown (new (map));
                OnKeyUp (new (map));

                break;
            case EventType.Mouse:
                MouseEventArgs me = ToDriverMouse (inputEvent.MouseEvent);

                //Debug.WriteLine ($"NetDriver: ({me.X},{me.Y}) - {me.Flags}");
                OnMouseEvent (me);

                break;
            case EventType.WindowSize:
                _winSizeChanging = true;
                Top = 0;
                Left = 0;
                Cols = inputEvent.WindowSizeEvent.Size.Width;
                Rows = Math.Max (inputEvent.WindowSizeEvent.Size.Height, 0);

                ResizeScreen ();
                ClearContents ();
                _winSizeChanging = false;
                OnSizeChanged (new (new (Cols, Rows)));

                break;
            case EventType.RequestResponse:
                break;
            case EventType.WindowPosition:
                break;
            default:
                throw new ArgumentOutOfRangeException ();
        }
    }

    internal override void End ()
    {
        if (IsWinPlatform)
        {
            NetWinConsole?.Cleanup ();
        }

        StopReportingMouseMoves ();

        _ansiResponseTokenSource?.Cancel ();
        _ansiResponseTokenSource?.Dispose ();

        _waitAnsiResponse?.Dispose ();

        if (!RunningUnitTests)
        {
            Console.ResetColor ();

            //Disable alternative screen buffer.
            Console.Out.Write (AnsiEscapeSequenceRequestUtils.CSI_RestoreCursorAndRestoreAltBufferWithBackscroll);

            //Set cursor key to cursor.
            Console.Out.Write (AnsiEscapeSequenceRequestUtils.CSI_ShowCursor);
            Console.Out.Close ();
        }
    }

    #endregion Init/End/MainLoop

    #region Color Handling

    public override bool SupportsTrueColor => Environment.OSVersion.Platform == PlatformID.Unix
                                              || (IsWinPlatform && Environment.OSVersion.Version.Build >= 14931);

    private const int COLOR_BLACK = 30;
    private const int COLOR_BLUE = 34;
    private const int COLOR_BRIGHT_BLACK = 90;
    private const int COLOR_BRIGHT_BLUE = 94;
    private const int COLOR_BRIGHT_CYAN = 96;
    private const int COLOR_BRIGHT_GREEN = 92;
    private const int COLOR_BRIGHT_MAGENTA = 95;
    private const int COLOR_BRIGHT_RED = 91;
    private const int COLOR_BRIGHT_WHITE = 97;
    private const int COLOR_BRIGHT_YELLOW = 93;
    private const int COLOR_CYAN = 36;
    private const int COLOR_GREEN = 32;
    private const int COLOR_MAGENTA = 35;
    private const int COLOR_RED = 31;
    private const int COLOR_WHITE = 37;
    private const int COLOR_YELLOW = 33;

    // Cache the list of ConsoleColor values.
    [UnconditionalSuppressMessage (
                                      "AOT",
                                      "IL3050:Calling members annotated with 'RequiresDynamicCodeAttribute' may break functionality when AOT compiling.",
                                      Justification = "<Pending>")]
    private static readonly HashSet<int> ConsoleColorValues = new (
                                                                   Enum.GetValues (typeof (ConsoleColor))
                                                                       .OfType<ConsoleColor> ()
                                                                       .Select (c => (int)c)
                                                                  );

    // Dictionary for mapping ConsoleColor values to the values used by System.Net.Console.
    private static readonly Dictionary<ConsoleColor, int> colorMap = new ()
    {
        { ConsoleColor.Black, COLOR_BLACK },
        { ConsoleColor.DarkBlue, COLOR_BLUE },
        { ConsoleColor.DarkGreen, COLOR_GREEN },
        { ConsoleColor.DarkCyan, COLOR_CYAN },
        { ConsoleColor.DarkRed, COLOR_RED },
        { ConsoleColor.DarkMagenta, COLOR_MAGENTA },
        { ConsoleColor.DarkYellow, COLOR_YELLOW },
        { ConsoleColor.Gray, COLOR_WHITE },
        { ConsoleColor.DarkGray, COLOR_BRIGHT_BLACK },
        { ConsoleColor.Blue, COLOR_BRIGHT_BLUE },
        { ConsoleColor.Green, COLOR_BRIGHT_GREEN },
        { ConsoleColor.Cyan, COLOR_BRIGHT_CYAN },
        { ConsoleColor.Red, COLOR_BRIGHT_RED },
        { ConsoleColor.Magenta, COLOR_BRIGHT_MAGENTA },
        { ConsoleColor.Yellow, COLOR_BRIGHT_YELLOW },
        { ConsoleColor.White, COLOR_BRIGHT_WHITE }
    };

    // Map a ConsoleColor to a platform dependent value.
    private int MapColors (ConsoleColor color, bool isForeground = true)
    {
        return colorMap.TryGetValue (color, out int colorValue) ? colorValue + (isForeground ? 0 : 10) : 0;
    }

    #endregion

    #region Cursor Handling

    private bool SetCursorPosition (int col, int row)
    {
        if (IsWinPlatform)
        {
            // Could happens that the windows is still resizing and the col is bigger than Console.WindowWidth.
            try
            {
                Console.SetCursorPosition (col, row);

                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }

        // + 1 is needed because non-Windows is based on 1 instead of 0 and
        // Console.CursorTop/CursorLeft isn't reliable.
        Console.Out.Write (AnsiEscapeSequenceRequestUtils.CSI_SetCursorPosition (row + 1, col + 1));

        return true;
    }

    private CursorVisibility? _cachedCursorVisibility;

    public override void UpdateCursor ()
    {
        EnsureCursorVisibility ();

        if (Col >= 0 && Col < Cols && Row >= 0 && Row <= Rows)
        {
            SetCursorPosition (Col, Row);
            SetWindowPosition (0, Row);
        }
    }

    public override bool GetCursorVisibility (out CursorVisibility visibility)
    {
        visibility = _cachedCursorVisibility ?? CursorVisibility.Default;

        return visibility == CursorVisibility.Default;
    }

    public override bool SetCursorVisibility (CursorVisibility visibility)
    {
        _cachedCursorVisibility = visibility;

        Console.Out.Write (visibility == CursorVisibility.Default ? AnsiEscapeSequenceRequestUtils.CSI_ShowCursor : AnsiEscapeSequenceRequestUtils.CSI_HideCursor);

        return visibility == CursorVisibility.Default;
    }

    public override bool EnsureCursorVisibility ()
    {
        if (!(Col >= 0 && Row >= 0 && Col < Cols && Row < Rows))
        {
            GetCursorVisibility (out CursorVisibility cursorVisibility);
            _cachedCursorVisibility = cursorVisibility;
            SetCursorVisibility (CursorVisibility.Invisible);

            return false;
        }

        SetCursorVisibility (_cachedCursorVisibility ?? CursorVisibility.Default);

        return _cachedCursorVisibility == CursorVisibility.Default;
    }

    #endregion

    #region Mouse Handling

    public void StartReportingMouseMoves ()
    {
        if (!RunningUnitTests)
        {
            Console.Out.Write (AnsiEscapeSequenceRequestUtils.CSI_EnableMouseEvents);
        }
    }

    public void StopReportingMouseMoves ()
    {
        if (!RunningUnitTests)
        {
            Console.Out.Write (AnsiEscapeSequenceRequestUtils.CSI_DisableMouseEvents);
        }
    }

    private MouseEventArgs ToDriverMouse (MouseEvent me)
    {
        //System.Diagnostics.Debug.WriteLine ($"X: {me.Position.X}; Y: {me.Position.Y}; ButtonState: {me.ButtonState}");

        MouseFlags mouseFlag = 0;

        if ((me.ButtonState & MouseButtonState.Button1Pressed) != 0)
        {
            mouseFlag |= MouseFlags.Button1Pressed;
        }

        if ((me.ButtonState & MouseButtonState.Button1Released) != 0)
        {
            mouseFlag |= MouseFlags.Button1Released;
        }

        if ((me.ButtonState & MouseButtonState.Button1Clicked) != 0)
        {
            mouseFlag |= MouseFlags.Button1Clicked;
        }

        if ((me.ButtonState & MouseButtonState.Button1DoubleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button1DoubleClicked;
        }

        if ((me.ButtonState & MouseButtonState.Button1TripleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button1TripleClicked;
        }

        if ((me.ButtonState & MouseButtonState.Button2Pressed) != 0)
        {
            mouseFlag |= MouseFlags.Button2Pressed;
        }

        if ((me.ButtonState & MouseButtonState.Button2Released) != 0)
        {
            mouseFlag |= MouseFlags.Button2Released;
        }

        if ((me.ButtonState & MouseButtonState.Button2Clicked) != 0)
        {
            mouseFlag |= MouseFlags.Button2Clicked;
        }

        if ((me.ButtonState & MouseButtonState.Button2DoubleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button2DoubleClicked;
        }

        if ((me.ButtonState & MouseButtonState.Button2TripleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button2TripleClicked;
        }

        if ((me.ButtonState & MouseButtonState.Button3Pressed) != 0)
        {
            mouseFlag |= MouseFlags.Button3Pressed;
        }

        if ((me.ButtonState & MouseButtonState.Button3Released) != 0)
        {
            mouseFlag |= MouseFlags.Button3Released;
        }

        if ((me.ButtonState & MouseButtonState.Button3Clicked) != 0)
        {
            mouseFlag |= MouseFlags.Button3Clicked;
        }

        if ((me.ButtonState & MouseButtonState.Button3DoubleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button3DoubleClicked;
        }

        if ((me.ButtonState & MouseButtonState.Button3TripleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button3TripleClicked;
        }

        if ((me.ButtonState & MouseButtonState.ButtonWheeledUp) != 0)
        {
            mouseFlag |= MouseFlags.WheeledUp;
        }

        if ((me.ButtonState & MouseButtonState.ButtonWheeledDown) != 0)
        {
            mouseFlag |= MouseFlags.WheeledDown;
        }

        if ((me.ButtonState & MouseButtonState.ButtonWheeledLeft) != 0)
        {
            mouseFlag |= MouseFlags.WheeledLeft;
        }

        if ((me.ButtonState & MouseButtonState.ButtonWheeledRight) != 0)
        {
            mouseFlag |= MouseFlags.WheeledRight;
        }

        if ((me.ButtonState & MouseButtonState.Button4Pressed) != 0)
        {
            mouseFlag |= MouseFlags.Button4Pressed;
        }

        if ((me.ButtonState & MouseButtonState.Button4Released) != 0)
        {
            mouseFlag |= MouseFlags.Button4Released;
        }

        if ((me.ButtonState & MouseButtonState.Button4Clicked) != 0)
        {
            mouseFlag |= MouseFlags.Button4Clicked;
        }

        if ((me.ButtonState & MouseButtonState.Button4DoubleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button4DoubleClicked;
        }

        if ((me.ButtonState & MouseButtonState.Button4TripleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button4TripleClicked;
        }

        if ((me.ButtonState & MouseButtonState.ReportMousePosition) != 0)
        {
            mouseFlag |= MouseFlags.ReportMousePosition;
        }

        if ((me.ButtonState & MouseButtonState.ButtonShift) != 0)
        {
            mouseFlag |= MouseFlags.ButtonShift;
        }

        if ((me.ButtonState & MouseButtonState.ButtonCtrl) != 0)
        {
            mouseFlag |= MouseFlags.ButtonCtrl;
        }

        if ((me.ButtonState & MouseButtonState.ButtonAlt) != 0)
        {
            mouseFlag |= MouseFlags.ButtonAlt;
        }

        return new() { Position = me.Position, Flags = mouseFlag };
    }

    #endregion Mouse Handling

    #region Keyboard Handling

    public override void SendKeys (char keyChar, ConsoleKey key, bool shift, bool alt, bool control)
    {
        var input = new InputResult
        {
            EventType = EventType.Key, ConsoleKeyInfo = new (keyChar, key, shift, alt, control)
        };

        try
        {
            ProcessInput (input);
        }
        catch (OverflowException)
        { }
    }

    private ConsoleKeyInfo FromVKPacketToKConsoleKeyInfo (ConsoleKeyInfo consoleKeyInfo)
    {
        if (consoleKeyInfo.Key != ConsoleKey.Packet)
        {
            return consoleKeyInfo;
        }

        ConsoleModifiers mod = consoleKeyInfo.Modifiers;
        bool shift = (mod & ConsoleModifiers.Shift) != 0;
        bool alt = (mod & ConsoleModifiers.Alt) != 0;
        bool control = (mod & ConsoleModifiers.Control) != 0;

        ConsoleKeyInfo cKeyInfo = DecodeVKPacketToKConsoleKeyInfo (consoleKeyInfo);

        return new (cKeyInfo.KeyChar, cKeyInfo.Key, shift, alt, control);
    }

    #endregion Keyboard Handling

    #region Low-Level DotNet tuff

    private readonly ManualResetEventSlim _waitAnsiResponse = new (false);
    private CancellationTokenSource? _ansiResponseTokenSource;

    /// <inheritdoc/>
    public override string? WriteAnsiRequest (AnsiEscapeSequenceRequest ansiRequest)
    {
        lock (ansiRequest._responseLock)
        {
            if (_mainLoopDriver is null)
            {
                return string.Empty;
            }
        }

        _ansiResponseTokenSource ??= new ();

        try
        {
            lock (ansiRequest._responseLock)
            {
                ansiRequest.ResponseFromInput += (s, e) =>
                                                 {
                                                     Debug.Assert (s == ansiRequest);
                                                     Debug.Assert (e == ansiRequest.Response);

                                                     _waitAnsiResponse.Set ();
                                                 };

                _mainLoopDriver._netEvents.EscSeqRequests.Add (ansiRequest);

                _mainLoopDriver._netEvents._forceRead = true;
            }

            _waitAnsiResponse.Wait (_ansiResponseTokenSource.Token);
        }
        catch (OperationCanceledException)
        {
            return string.Empty;
        }

        lock (ansiRequest._responseLock)
        {
            _mainLoopDriver._netEvents._forceRead = false;

            if (_mainLoopDriver._netEvents.EscSeqRequests.Statuses.TryPeek (out AnsiEscapeSequenceRequestStatus? request))
            {
                if (_mainLoopDriver._netEvents.EscSeqRequests.Statuses.Count > 0
                    && string.IsNullOrEmpty (request.AnsiRequest.Response))
                {
                    lock (request.AnsiRequest._responseLock)
                    {
                        // Bad request or no response at all
                        _mainLoopDriver._netEvents.EscSeqRequests.Statuses.TryDequeue (out _);
                    }
                }
            }

            _waitAnsiResponse.Reset ();

            return ansiRequest.Response;
        }
    }

    /// <inheritdoc/>
    public override void WriteRaw (string ansi) { throw new NotImplementedException (); }

    private volatile bool _winSizeChanging;

    private void SetWindowPosition (int col, int row)
    {
        if (!RunningUnitTests)
        {
            Top = Console.WindowTop;
            Left = Console.WindowLeft;
        }
        else
        {
            Top = row;
            Left = col;
        }
    }

    private void ResizeScreen ()
    {
        // Not supported on Unix.
        if (IsWinPlatform)
        {
            // Can raise an exception while is still resizing.
            try
            {
#pragma warning disable CA1416
                if (Console.WindowHeight > 0)
                {
                    Console.CursorTop = 0;
                    Console.CursorLeft = 0;
                    Console.WindowTop = 0;
                    Console.WindowLeft = 0;

                    if (Console.WindowHeight > Rows)
                    {
                        Console.SetWindowSize (Cols, Rows);
                    }

                    Console.SetBufferSize (Cols, Rows);
                }
#pragma warning restore CA1416
            }

            // INTENT: Why are these eating the exceptions?
            // Comments would be good here.
            catch (IOException)
            {
                // CONCURRENCY: Unsynchronized access to Clip is not safe.
                Clip = new (0, 0, Cols, Rows);
            }
            catch (ArgumentOutOfRangeException)
            {
                // CONCURRENCY: Unsynchronized access to Clip is not safe.
                Clip = new (0, 0, Cols, Rows);
            }
        }
        else
        {
            Console.Out.Write (AnsiEscapeSequenceRequestUtils.CSI_SetTerminalWindowSize (Rows, Cols));
        }

        // CONCURRENCY: Unsynchronized access to Clip is not safe.
        Clip = new (0, 0, Cols, Rows);
    }

    #endregion Low-Level DotNet tuff
}