DllImport错误：无法找到名为的入口点 [英] DllImport error: unable to find an entry point named

问题描述

我有一个名为WD_SDK.dll的DLL文件（它与SDK.h文件一起使用）。我打开SDK.h，我看到

  typedef   void （CALLBACK * VideoCaptureCB_Ptr）（PVOID pContext，BYTE * apData [ 3 ]，
 VideoSampleInfo_T * pVSI ）; 
 
  typedef   struct  _VideoSampleInfo_T 
 {
 ULONG idFormat ;  //    
 ULONG lSignalState; 
  int  nLen;  //  未用于原始视频数据（例如YUV420） 
  int  nWidth; 
  int  nHeight; 
  int  anPitchs [ 3 ];  //  仅用于原始视频数据（例如YUV420） 
 ULONG dwMicrosecsPerFrame;  //   1000 * 1000 / FPS  
 ULONG字段; 
  int  iSerial; 
 
} VideoSampleInfo_T; 
 
 WD_RegisterVideoPreviewCB（HANDLE hChannel，PVOID pContext，VideoCaptureCB_Ptr pCB）; 

我想调用WD_RegisterVideoPreviewCB in C＃。所以我使用DllImport在C＃中声明它。它看起来像这样：

 [DllImport（  WD_SDK.dll，EntryPoint =   _ WD_RegisterVideoPreviewCB @ 12，ExactSpelling =  true ）] 
 静态  extern   int  WD_RegisterVideoPreviewCB（ IntPtr  hChannel， object  pContext，VideoCaptureCB_Ptr pCB）; 

然后我重新声明C ++结构和C＃中的CALLBACK如下：

  public   delegate   void  VideoCaptureCB_Ptr（ IntPtr  pContext， byte  [] apData，Video SampleInfo_T pVSI）; 
 
 [StructLayout（LayoutKind.Sequential）] 
  public   struct  VideoSampleInfo_T 
 {
  public   uint  idFormat; 
  public   uint  lSignalState; 
  public   int  nLen;  //  未用于原始视频数据（例如YUV420） 
  public   int  nWidth; 
  public   int  nHeight; 
  public   int  [] anPitchs;  //  仅用于原始视频数据（例如YUV420） 
  public   uint  dwMicrosecsPerFrame;  //   1000 * 1000 / FPS  
  public   uint 字段; 
  public   int  iSerial; 
 
} 

和一个代表工具



当我运行我的代码时

 WD_RegisterVideoPreviewCB（m_ahChannels [i]，m_aMediaHandler [i]，HandleVideoStatic）; 

程序显示错误与非托管目标签名不符。



我认为遇到了PVOID pContext的问题，我将其更改为对象pContext。但是我必须将m_aMediaHandler [i]（它是一个类的实例而不是指针）传递给它，错误引发..无效的agruments



请帮我纠正这段代码。提前谢谢。

解决方案

我不知道你在哪里得到了_WD_RegisterVideoPreviewCB @ 12。这个名字看起来很现实，但是更好的检查。



最简单的方法是在导出的DLL上运行一些二进制转储实用程序。它可以是DUMPBIN.EXE：

http://msdn.microsoft.com/en-us/library/c1h23y6c.aspx [ ^ ]。



您可以从Visual Studio菜单中的Visual Studio命令提示符运行此实用程序。

- SA

I have an DLL file named WD_SDK.dll ( it go with an SDK.h file ). I open the SDK.h and I see

typedef void (CALLBACK * VideoCaptureCB_Ptr)(PVOID pContext, BYTE * apData[3],
VideoSampleInfo_T * pVSI);

typedef struct _VideoSampleInfo_T
{
    ULONG   idFormat; // 
    ULONG   lSignalState;
    int     nLen; // not used for raw video data(e.g. YUV420)
    int     nWidth;
    int     nHeight;
    int     anPitchs[3]; // only used for raw video data(e.g. YUV420)
    ULONG   dwMicrosecsPerFrame; // 1000*1000/FPS
    ULONG   field;
    int     iSerial;

} VideoSampleInfo_T;

WD_RegisterVideoPreviewCB(HANDLE hChannel, PVOID pContext, VideoCaptureCB_Ptr pCB);

I want to call the WD_RegisterVideoPreviewCB in C#. So I use the DllImport to declare it in C#. It look like this:

[DllImport("WD_SDK.dll", EntryPoint = "_WD_RegisterVideoPreviewCB@12", ExactSpelling = true)]
        static extern int WD_RegisterVideoPreviewCB(IntPtr hChannel,  object pContext, VideoCaptureCB_Ptr pCB);

Then i re-declare the C++ struct and CALLBACK in C# like this:

public delegate void VideoCaptureCB_Ptr(IntPtr pContext, byte[] apData, VideoSampleInfo_T pVSI);

[StructLayout(LayoutKind.Sequential)]
    public struct VideoSampleInfo_T
    {
        public uint idFormat;
        public uint lSignalState;
        public int nLen; // not used for raw video data(e.g. YUV420)
        public int nWidth;
        public int nHeight;
        public int[] anPitchs; // only used for raw video data(e.g. YUV420)
        public uint dwMicrosecsPerFrame; // 1000*1000/FPS
        public uint field;
        public int iSerial;

    }

And one delegate implement

When i run my code

WD_RegisterVideoPreviewCB(m_ahChannels[i],  m_aMediaHandler[i], HandleVideoStatic);

THe program show me an error "does not match the unmanaged target signature. "

I thinks encountered problem with the PVOID pContext, I changed it to object pContext. But i have to pass the m_aMediaHandler[i] ( It's an instance of a class not a pointer ) to it, the error raised " .."invalid agruments"

Please help me to correct this code. Thanks in advance.

解决方案

I don't know where did you get "_WD_RegisterVideoPreviewCB@12". This name looks realistic, but better check it up.

The simplest way to do so is running some binary dump utility on your exported DLL. It can be DUMPBIN.EXE:
http://msdn.microsoft.com/en-us/library/c1h23y6c.aspx[^].

You can run this utility from the Visual Studio Command Prompt found in Visual Studio menu.

—SA

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