C # Call an unmanaged DLL parameter transfer Memorandum

When the unmanaged parameters are const mystruct * mystructinstance and mystruct * mystructinstance, the C # program can pass the parameters through ref mystruct mystructinstance.
In 2, c ++, and C, the long value is 4 bytes, and the conversion to C # Is int type.
For example
Definition in C, C ++
Typedef struct hs_rect
{
Long left;
Long top;
Long right;
Long bottom;
} Hs_rect;
In C #, it should be
[Structlayout (layoutkind. Sequential, charset = charset. ANSI)]
Public struct hs_rect
{
Public int left;
Public int top;
Public int right;
Public int bottom;
};
3. Convert struct to pointer type
// Define an eyepoint as an hs_eyepoint struct.
Featuredata. hs_eyepoint eyepoint;
// Define peye as a pointer to hs_eyepoint
Intptr peye = marshal. alloccotaskmem (marshal. sizeof (typeof (featuredata. hs_eyepoint )));
// Convert eyepoint to peye, that is, let peye point to the eyepoint address
Marshal. structuretoptr (eyepoint, peye, true );
// Program Processing
Nretcode = hs_locateeye (pbygrayimage, nimagewidth [0], nimageheight [0],
Ref rcface, ref eyepoint );
// After processing, the pointer is restored to a struct.
Eyepoint = (featuredata. hs_eyepoint) Marshal. ptrtostructure (peye, typeof (featuredata. hs_eyepoint ));
// Release the space pointed to by the pointer
Marshal. freecotaskmem (pface );

Code:

Using system;
Using system. Collections. Generic;
Using system. componentmodel;
Using system. Data;
Using system. drawing;
Using system. text;
Using system. Windows. forms;
Using system. runtime. interopservices;

Namespace featureextraction
{
Public partial class form1: Form
{

// Call functions in C DLL
[Dllimport ("hisign_faceid.dll", entrypoint = "hs_initfaceidsdk", charset = charset. ANSI, callingconvention = callingconvention. stdcall)]
Public static extern int hs_initfaceidsdk (featuredata. hs_facemode enmode );

[Dllimport ("hisign_faceid.dll", entrypoint = "hs_getfacefeaturesize", charset = charset. ANSI, callingconvention = callingconvention. stdcall)]
Public static extern int hs_getfacefeaturesize ();

[Dllimport ("hisign_faceid.dll", entrypoint = "hs_getimagesize", charset = charset. ANSI, callingconvention = callingconvention. stdcall)]
Public static extern int hs_getimagesize (string strimagepathname, int [] nimagewidth, int [] nimageheight );
// Int _ stdcall hs_getimagesize (const char * strimagepathname, int * nimagewidth, int * nimageheight );

[Dllimport ("hisign_faceid.dll", entrypoint = "hs_getgrayimagefromfile", charset = charset. ANSI, callingconvention = callingconvention. stdcall)]
Public static extern int hs_getgrayimagefromfile (string strimagepathname, byte [] pbyoutgrayimage );
// Int _ stdcall hs_getgrayimagefromfile (const char * strimagepathname, byte * pbyoutgrayimage );

[Dllimport ("hisign_faceid.dll", entrypoint = "hs_facedetection", charset = charset. ANSI, callingconvention = callingconvention. stdcall)]
Public static extern int hs_facedetection (byte [] pbygrayimage, int nimagewidth, int nimageheight, int nminfacesize,
Int nmaxfacesize, ref featuredata. hs_facecandidate poutfacecand, int [] nfacenum );
// Int _ stdcall hs_facedetection (const byte * pbygrayimage, int nimagewidth, int nimageheight, int nminfacesize,
// Int nmaxfacesize, hs_facecandidate * poutfacecand, int * nfacenum );

[Dllimport ("hisign_faceid.dll", entrypoint = "hs_locateeye", charset = charset. ANSI, callingconvention = callingconvention. stdcall)]
Public static extern int hs_locateeye (byte [] pbygrayimage, int nimagewidth, int nimageheight, ref featuredata. hs_rect pfacerect, ref featuredata. hs_eyepoint peyepoint );
// Int _ stdcall hs_locateeye (const byte * pbygrayimage, int nimagewidth, int nimageheight,
// Const hs_rect * pfacerect, hs_eyepoint * peyepoint );

[Dllimport ("hisign_faceid.dll", entrypoint = "hs_faceextractionbyeyepos", charset = charset. ANSI, callingconvention = callingconvention. stdcall)]
Public static extern int hs_faceextractionbyeyepos (byte [] pbygrayimage, int nimagewidth, int nimageheight, ref featuredata. hs_eyepoint peyepoint, byte [] pbyfeature );
// Int _ stdcall hs_faceextractionbyeyepos (const byte * pbygrayimage, int nimagewidth, int nimageheight,
// Const hs_eyepoint * peyepoint, byte * pbyfeature );

[Dllimport ("hisign_faceid.dll", entrypoint = "hs_uninitfaceidsdk", charset = charset. ANSI, callingconvention = callingconvention. stdcall)]
Public static extern int hs_uninitfaceidsdk ();
// Int _ stdcall hs_uninitfaceidsdk ();

Public form1 ()
{
Initializecomponent ();

 

}

Private void button2_click (Object sender, eventargs E)
{
Int retcode = getdone ();
}

Private int getdone ()
{
Featuredata. hs_facemode enmode; // working mode of Face Recognition
Int nretcode; // return code
Featuredata. hs_facecandidate [] pfacecand; // a candidate for Face Detection
Int [] nfacenum = new int [1]; // number of detected faces
String strimagepath = @ "C: \ Documents ents and Settings \ kingking \ My Documents ents \ my pictures \ me \ 344.jpg"; // face image name
Int [] nimagewidth = new int [1]; // image width and height
Int [] nimageheight = new int [1];
Byte [] pbygrayimage = NULL; // grayscale image buffer
Featuredata. hs_eyepoint eyepoint = new featuredata. hs_eyepoint (); // eye position
Int nfeatsize; // obtain the number of bytes of facial features of the current SDK.
Byte [] pbyfeatures = NULL; // feature Buffer

// Initialize the SDK
Enmode = featuredata. hs_facemode.hs_verify;
Nretcode = hs_initfaceidsdk (enmode );
If (nretcode! = Featuredata. hisign_err_none)
{
Return nretcode;
}

// Obtain the size of the face features in bytes
Nfeatsize = hs_getfacefeaturesize ();

// Read the face image from the file and convert the face image into a grayscale image
Nretcode = hs_getimagesize (strimagepath, nimagewidth, nimageheight );
Pbygrayimage = new byte [nimagewidth [0] * nimageheight [0];
Nretcode = hs_getgrayimagefromfile (strimagepath, pbygrayimage );

Pfacecand = new featuredata. hs_facecandidate [100]; // allocate memory for Face Detection results

// Perform Face Detection
Nretcode = hs_facedetection (pbygrayimage, nimagewidth [0], nimageheight [0], 20,
(Nimagewidth [0]> = nimageheight [0]? Nimageheight [0]: nimagewidth [0]), ref pfacecand [0], nfacenum );

// Locate the eyes of each detected face
For (INT I = 0; I <nfacenum [0]; ++ I)
{
Featuredata. hs_rect rcface;
Rcface. Left = pfacecand [I]. trueleft;
Rcface. Top = pfacecand [I]. truetop;
Rcface. Right = pfacecand [I]. trueright;
Rcface. Bottom = pfacecand [I]. truebottom;

// Intptr prcface = marshal. alloccotaskmem (marshal. sizeof (rcface ));
// Marshal. structuretoptr (rcface, prcface, false );

Intptr pface = marshal. alloccotaskmem (marshal. sizeof (typeof (featuredata. hs_rect )));
Marshal. structuretoptr (rcface, pface, true );
Intptr peye = marshal. alloccotaskmem (marshal. sizeof (typeof (featuredata. hs_eyepoint )));
Nretcode = hs_locateeye (pbygrayimage, nimagewidth [0], nimageheight [0],
Ref rcface, ref eyepoint );

// Eyepoint = (featuredata. hs_eyepoint) Marshal. ptrtostructure (peye, typeof (featuredata. hs_eyepoint ));
Marshal. freecotaskmem (pface );
Marshal. freecotaskmem (peye );

// Extract features
Pbyfeatures = new byte [nfeatsize];
Nretcode = hs_faceextractionbyeyepos (pbygrayimage, nimagewidth [0],
Nimageheight [0], ref eyepoint, pbyfeatures );

Pbyfeatures = NULL;
// Marshal. freehglobal (prcface );
}

Pbygrayimage = NULL;
Pfacecand = NULL;

// Release SDK Resources
Nretcode = hs_uninitfaceidsdk ();

Return nretcode;

}
}