MIDIHDR 问题

发布于 2024-11-08 11:02:36 字数 731 浏览 9 评论 0原文

我正在尝试在 WinMM.dll 中为 MIDI 函数编写一个包装库，但我在处理 MIDI 长消息时遇到了问题。我在 PIvnoke.net 中找到了这个（我自己添加了第一行）：

[StructLayout(LayoutKind.Sequential)]
    public struct MIDIHDR
    {
        IntPtr lpData;
        int dwBufferLength;
        int dwBytesRecorded;
        IntPtr dwUser;
        int dwFlags;
        MIDIHDR lpNext;
        IntPtr reserved;
        int dwOffset;
        IntPtr dwReserved;
    }

但是编译时出现错误：

错误 1 类型为“WinMMM.MidiWrapper.MIDIHDR”的结构成员“WinMMM.MidiWrapper.MIDIHDR.lpNext”导致结构布局中发生循环 C:\Users\Alex\Documents\Visual Studio 2010\Projects\WinMMM\WinMMM \MidiWrapper.cs 219 21 WinMMM

我正在使用 Visual Studio Ultimate 2010，我正在制作一个 C# 类库，任何帮助将不胜感激！

原文

I am trying to write a wrapper library for MIDI functions in WinMM.dll, but I am having trouble with MIDI long messages. I found this in PIvnoke.net (I added the first line myself):

[StructLayout(LayoutKind.Sequential)]
    public struct MIDIHDR
    {
        IntPtr lpData;
        int dwBufferLength;
        int dwBytesRecorded;
        IntPtr dwUser;
        int dwFlags;
        MIDIHDR lpNext;
        IntPtr reserved;
        int dwOffset;
        IntPtr dwReserved;
    }

But I get an error while compiling:

Error 1 Struct member 'WinMMM.MidiWrapper.MIDIHDR.lpNext' of type 'WinMMM.MidiWrapper.MIDIHDR' causes a cycle in the struct layout C:\Users\Alex\Documents\Visual Studio 2010\Projects\WinMMM\WinMMM\MidiWrapper.cs 219 21 WinMMM

I am using Visual Studio Ultimate 2010, I am making a C# class library, and any help will be appreciated!

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柳絮泡泡 2024-11-15 11:02:36

您可以将: 更改

MIDIHDR lpNext;

为:

IntPtr lpNext;

来解决您眼前的问题。

MIDL 编译器无法取消引用这些结构链，但如果 API 调用将一个结构作为参数，则通过此更改，到下一个结构的链接将被解码为原始指针，就像第一个字段 lpData 一样代码>.

You can change:

MIDIHDR lpNext;

to:

IntPtr lpNext;

to solve your immediate problem.

The MIDL compiler can't dereference a chain of these structures but if an API call takes one as an argument, with this change the link to the next one will be decoded as a raw pointer, just like first field lpData.

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爱，才寂寞 2024-11-15 11:02:36

我不确定你正确的最后一点是否正确。 dwReserved 是一个由四个 DWORD_PTR 组成的数组（请参阅 MIDIHDR MSDN）。你可以使用这样的东西：

    // http://msdn.microsoft.com/en-us/library/dd798449%28VS.85%29.aspx
    [StructLayout(LayoutKind.Sequential)]
    public struct MIDIHDR
    {
        public string lpData;
        public int dwBufferLength;
        public int dwBytesRecorded;
        public IntPtr dwUser;
        public int dwFlags;
        public IntPtr lpNext;
        public IntPtr reserved;
        public int dwOffset;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
        public IntPtr[] dwReserved;
    }

I'm not sure the final bit of your correct is right. dwReserved is an array of four DWORD_PTRs (see MIDIHDR on MSDN). You could use something like this:

    // http://msdn.microsoft.com/en-us/library/dd798449%28VS.85%29.aspx
    [StructLayout(LayoutKind.Sequential)]
    public struct MIDIHDR
    {
        public string lpData;
        public int dwBufferLength;
        public int dwBytesRecorded;
        public IntPtr dwUser;
        public int dwFlags;
        public IntPtr lpNext;
        public IntPtr reserved;
        public int dwOffset;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
        public IntPtr[] dwReserved;
    }

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