c# - C# 字节数组中的 RAWINPUT RAWHID 结构

Question

我正在尝试使用以下方法从 HID 设备读取数据:

uint dwsize = 0;
//RAWINPUT input = new RAWINPUT();
uint result = GetRawInputData(lParam, RID_INPUT, IntPtr.Zero, ref dwsize, Marshal.SizeOf(typeof(RAWINPUTHEADER)));

//_rawBuffer = new RAWINPUT(new RAWINPUTHEADER(), new RAWDATA(new RAWKEYBOARD(), new RAWHID(0,0)));
result = GetRawInputData(lParam, RID_INPUT, out _rawBuffer, ref dwsize, Marshal.SizeOf(typeof(RAWINPUTHEADER)));

此代码有效，但从 RAWHID 结构中获取字节数组存在一个问题，根据 MSDN 文档，它应该是这样的:

typedef struct tagRAWHID {
  DWORD dwSizeHid;
  DWORD dwCount;
  BYTE  bRawData[1];
} RAWHID, *PRAWHID, *LPRAWHID;

这是我的:

[StructLayout(LayoutKind.Sequential)]
internal struct RAWHID
{
  public uint dwSizHid;
  public uint dwCount;
  public byte bRawData;
}

我试图到处寻找，但找不到有效的解决方案。我还尝试使用此代码获取 IntPtr 而不是字节数组并编码复制它:

int length = (int)(_rawBuffer.data.hid.dwCount * _rawBuffer.data.hid.dwSizHid);
byte[] bytes = new byte[length];
GCHandle pinnedPacket = GCHandle.Alloc(_rawBuffer.data.hid.bRawData, GCHandleType.Pinned);
Marshal.Copy(_rawBuffer.data.hid.bRawData, bytes, 0, length);
pinnedPacket.Free();

我固定它的原因是因为我不断收到

System.AccessViolationException: 'Attempted to read or write protected memory. This is often an indication that other memory is corrupt.'

错误。

问题简短:如何使 RAWHID 结构与 C# 中的字节数组一起使用

Answer 1

我也不确定如何在结构中定义动态大小的字节数组 BYTE bRawData[1]，所以我最终从原始 IntPtr 中获取它。我刚刚从 RAWHID 定义中删除了它:

[StructLayout(LayoutKind.Sequential)]
public struct RAWHID
{
    public int Size;
    public int Count;
}

[StructLayout(LayoutKind.Sequential)]
public struct RawInput
{
    /// <summary>
    /// Header for the data.
    /// </summary>
    public RawInputHeader Header;
    public Union Data;

    [StructLayout(LayoutKind.Explicit)]
    public struct Union
    {
        [FieldOffset(0)] public RAWMOUSE Mouse;
        [FieldOffset(0)] public RAWKEYBOARD Keyboard;
        [FieldOffset(0)] public RAWHID HID;
    }
}

下面是我实际读取数据并将其写入控制台的方式:

private static void ProcessInputMessage(Message message)
{
    var headerSize = (uint) Marshal.SizeOf<RawInputHeader>();
    uint rawInputSize = 0;
    var result = GetRawInputData(message.LParam, RID_INPUT, IntPtr.Zero, ref rawInputSize, headerSize);
    if (result != 0)
    {
        Console.WriteLine($"Failed to get message size: {result}");
        return;
    }

    using var rawInputPointer = new AllocHGlobalWrapper(rawInputSize);
    if (!rawInputPointer.Success)
    {
        return;
    }

    result = GetRawInputData(message.LParam, RID_INPUT, rawInputPointer.Value, ref rawInputSize, headerSize);
    if (result != rawInputSize)
    {
        Console.WriteLine($"Failed to get raw data: {result}");
        return;
    }
    
    var input = Marshal.PtrToStructure<RawInput>(rawInputPointer.Value);
    var buffer = new IntPtr(rawInputPointer.Value.ToInt64() + headerSize + Marshal.SizeOf<RAWHID>());

    if (input.Header.Type == RawInputType.HID)
    {
        for(var i  = 0; i < input.Data.HID.Count; i++)
        {
            var data = new byte[input.Data.HID.Size];
            Marshal.Copy(buffer, data, i * input.Data.HID.Size, input.Data.HID.Size);
            Console.WriteLine(BitConverter.ToString(data));
        }
    }
}

请注意，AllocHGlobalWrapper 只是我编写的一个简单助手，用于将对 Marshal.AllocHGlobal(...) 的调用包装在调用 Marshal.FreeHGlobal( ...) 当它被处理时，所以 rawInputPointer.Value 只是返回指向分配给 RawInput 的内存的 IntPtr .