WinFormsMouseAdapter.cs

using Gondwana.Input.Keyboard;
using Gondwana.Input.Mouse;
using Gondwana.WinForms.Rendering;
 
namespace Gondwana.WinForms.Input.Mouse;

public sealed class WinFormsMouseAdapter : IMouseAdapter, IDisposable
{
    private readonly Control _control;
    private readonly HashSet<MouseButton> _pressed = new();
    private readonly object _pressedLock = new();
    private Point _currentPosition;
    private KeyboardModifierState _modifiers;
    private int _scrollDelta;

    public Point CurrentPosition => _control switch
    {
        WinFormGpuRenderSurfaceControl gpu => gpu.Adapter?.AdapterPxToScreenPx(_currentPosition) ?? _currentPosition,
        WinFormBitmapRenderSurfaceControl bitmap => bitmap.Adapter.AdapterPxToScreenPx(_currentPosition),
        _ => _currentPosition
    };

    public HashSet<MouseButton> PressedButtons
    {
        get
        {
            var osButtons = Control.MouseButtons;
            lock (_pressedLock)
            {
                if (!osButtons.HasFlag(MouseButtons.Left)) _pressed.Remove(MouseButton.Left);
                if (!osButtons.HasFlag(MouseButtons.Right)) _pressed.Remove(MouseButton.Right);
                if (!osButtons.HasFlag(MouseButtons.Middle)) _pressed.Remove(MouseButton.Middle);
                return new HashSet<MouseButton>(_pressed);
            }
        }
    }

    public KeyboardModifierState CurrentKeyboardModifiers => _modifiers;

    public int ScrollDelta => Interlocked.Exchange(ref _scrollDelta, 0); // one-time read & reset

    public WinFormsMouseAdapter(Control control)
    {
        _control = control ?? throw new ArgumentNullException(nameof(control));
 
        _control.MouseDown += OnMouseDown;
        _control.MouseUp += OnMouseUp;
        _control.MouseMove += OnMouseMove;
        _control.MouseWheel += OnMouseWheel;
    }
 
    private void OnMouseDown(object? sender, System.Windows.Forms.MouseEventArgs e)
    {
        lock (_pressedLock)
            _pressed.Add(MapButton(e.Button));
        UpdatePosition(e);
    }
 
    private void OnMouseUp(object? sender, System.Windows.Forms.MouseEventArgs e)
    {
        lock (_pressedLock)
            _pressed.Remove(MapButton(e.Button));
        UpdatePosition(e);
    }
 
    private void OnMouseMove(object? sender, System.Windows.Forms.MouseEventArgs e)
    {
        UpdatePosition(e);
    }
 
    private void UpdatePosition(System.Windows.Forms.MouseEventArgs e)
    {
        _currentPosition = e.Location;
 
        _modifiers = KeyboardModifierState.None;
        if (Control.ModifierKeys.HasFlag(Keys.Shift)) _modifiers |= KeyboardModifierState.Shift;
        if (Control.ModifierKeys.HasFlag(Keys.Control)) _modifiers |= KeyboardModifierState.Ctrl;
        if (Control.ModifierKeys.HasFlag(Keys.Alt)) _modifiers |= KeyboardModifierState.Alt;
    }
 
    private static MouseButton MapButton(MouseButtons btn) => btn switch
    {
        MouseButtons.Left => MouseButton.Left,
        MouseButtons.Right => MouseButton.Right,
        MouseButtons.Middle => MouseButton.Middle,
        _ => MouseButton.None
    };
 
    private void OnMouseWheel(object? sender, System.Windows.Forms.MouseEventArgs e)
    {
        Interlocked.Add(ref _scrollDelta, e.Delta);
    }

    public void Dispose()
    {
        _control.MouseDown -= OnMouseDown;
        _control.MouseUp -= OnMouseUp;
        _control.MouseMove -= OnMouseMove;
        _control.MouseWheel -= OnMouseWheel;
    }
}