WPF 从裸 Win 32 的 WM_Pointer 消息获取触摸点绘制笔迹

>  PresentationCore.dll!System.Windows.Interop.HwndPointerInputProvider.System.Windows.Interop.IStylusInputProvider.FilterMessage(nint hwnd, MS.Internal.Interop.WindowMessage msg, nint wParam, nint lParam, ref bool handled)

  nint IStylusInputProvider.FilterMessage(nint hwnd, WindowMessage msg, nint wParam, nint lParam, ref bool handled)
  {
    handled = false;
    if (PointerLogic.IsEnabled)
    {
      switch (msg)
      {
      case WindowMessage.WM_ENABLE:
        IsWindowEnabled = MS.Win32.NativeMethods.IntPtrToInt32(wParam) == 1;
        break;
      case WindowMessage.WM_POINTERENTER:
        handled = ProcessMessage(GetPointerId(wParam), RawStylusActions.InRange, Environment.TickCount);
        break;
      case WindowMessage.WM_POINTERUPDATE:
        handled = ProcessMessage(GetPointerId(wParam), RawStylusActions.Move, Environment.TickCount);
        break;
      case WindowMessage.WM_POINTERDOWN:
        handled = ProcessMessage(GetPointerId(wParam), RawStylusActions.Down, Environment.TickCount);
        break;
      case WindowMessage.WM_POINTERUP:
        handled = ProcessMessage(GetPointerId(wParam), RawStylusActions.Up, Environment.TickCount);
        break;
      case WindowMessage.WM_POINTERLEAVE:
        handled = ProcessMessage(GetPointerId(wParam), RawStylusActions.OutOfRange, Environment.TickCount);
        break;
      }
    }
    return IntPtr.Zero;
  }

    public App()
    {
        AppContext.SetSwitch("Switch.System.Windows.Input.Stylus.EnablePointerSupport", true);
    }

    public MainWindow()
    {
        InitializeComponent();

        SourceInitialized += OnSourceInitialized;
    }

    private void OnSourceInitialized(object? sender, EventArgs e)
    {
        var windowInteropHelper = new WindowInteropHelper(this);
        var hwnd = windowInteropHelper.Handle;

        HwndSource source = HwndSource.FromHwnd(hwnd)!;
        source.AddHook(Hook);
    }

    private unsafe IntPtr Hook(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam, ref bool handled)
    {
        ... // 忽略其他代码
        return IntPtr.Zero;
    }

    private unsafe IntPtr Hook(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam, ref bool handled)
    {
        const int WM_POINTERDOWN = 0x0246;
        const int WM_POINTERUPDATE = 0x0245;
        const int WM_POINTERUP = 0x0247;

        if (msg is WM_POINTERDOWN or WM_POINTERUPDATE or WM_POINTERUP)
        {
             // 在这里打断点，如果能进断点则证明 Pointer 消息开启成功
        }

        ... // 忽略其他代码
        return IntPtr.Zero;
    }

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net9.0-windows</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <UseWPF>true</UseWPF>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.Windows.CsWin32" PrivateAssets="all" Version="0.3.106" />
  </ItemGroup>
</Project>

GetPointerTouchInfo
ScreenToClient
RegisterTouchWindow
WM_TOUCH
GetTouchInputInfo
GetPointerDeviceRects
ClientToScreen

            var pointerId = (uint) (ToInt32(wparam) & 0xFFFF);
            PInvoke.GetPointerTouchInfo(pointerId, out var info);

            POINTER_INFO pointerInfo = info.pointerInfo;

            var point = pointerInfo.ptPixelLocation;

            PInvoke.ScreenToClient(new HWND(hwnd), ref point);

            global::Windows.Win32.Foundation.RECT pointerDeviceRect = default;
            global::Windows.Win32.Foundation.RECT displayRect = default;

            PInvoke.GetPointerDeviceRects(pointerInfo.sourceDevice, &pointerDeviceRect, &displayRect);

            // 如果想要获取比较高精度的触摸点，可以使用 ptHimetricLocationRaw 字段
            // 由于 ptHimetricLocationRaw 采用的是 pointerDeviceRect 坐标系，需要转换到屏幕坐标系
            // 转换方法就是先将 ptHimetricLocationRaw 的 X 坐标，压缩到 [0-1] 范围内，然后乘以 displayRect 的宽度，再加上 displayRect 的 left 值，即得到了屏幕坐标系的 X 坐标。压缩到 [0-1] 范围内的方法就是除以 pointerDeviceRect 的宽度
            // 为什么需要加上 displayRect.left 的值？考虑多屏的情况，屏幕可能是副屏
            // Y 坐标同理
           var point2D = new Point2D(
                pointerInfo.ptHimetricLocationRaw.X / (double) pointerDeviceRect.Width * displayRect.Width +
                displayRect.left,
                pointerInfo.ptHimetricLocationRaw.Y / (double) pointerDeviceRect.Height * displayRect.Height +
                displayRect.top);

readonly record struct Point2D(double X, double Y);

            var screenTranslate = new Point(0, 0);
            PInvoke.ClientToScreen(new HWND(hwnd), ref screenTranslate);

            var dpi = VisualTreeHelper.GetDpi(this);

            point2D = new Point2D(point2D.X - screenTranslate.X, point2D.Y - screenTranslate.Y);
            point2D = new Point2D(point2D.X / dpi.DpiScaleX, point2D.Y / dpi.DpiScaleY);

            if (msg == WM_POINTERUPDATE)
            {
                var strokeVisual = GetStrokeVisual(pointerId);
                strokeVisual.Add(new StylusPoint(point2D.X, point2D.Y));
                strokeVisual.Redraw();
            }
            else if (msg == WM_POINTERUP)
            {
                StrokeVisualList.Remove(pointerId);
            }

git init
git remote add origin https://gitee.com/lindexi/lindexi_gd.git
git pull origin 322313ee55d0eeaae7148b24ca279e1df087871e

git remote remove origin
git remote add origin https://github.com/lindexi/lindexi_gd.git
git pull origin 322313ee55d0eeaae7148b24ca279e1df087871e