How to call CALLBACK from inside DLL
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Thread: How to call CALLBACK from inside DLL

  1. #1
    Join Date
    Sep 2011
    Posts
    0

    Angry How to call CALLBACK from inside DLL

    Hi

    I make a wraper dll ...

    So, I need to export to aplication some result...

    Well. this is code:

    xVideo.h

    #ifndef xVideoDEF

    #define xVideoDEF(f) WINAPI f

    #endif



    typedef BOOL (CALLBACK CallBackEnumerator)(char * name,GUID guid,void * user);

    /*

    name - the device name

    GUID - the device CLSID

    user - The 'user' parameter

    */



    //xVideo_Capture_xxx functions flags

    //...........................................

    #define xVideo_AudioCapture 0x10066

    #define xVideo_VideoCapture 0x10080



    int xVideoDEF(xVideo_CaptureGetDevices)(DWORD devicetype,CallBackEnumerator *callback,void* user);

    // Of course, this is only part of xVideo.h, But I only have problems with callbacks, This here is only one from

    //several simiral callbacks

    //************************************************************

    main.cpp
    #include <windows.h>
    #include <xVideo.h>
    using namespace std;
    #define export extern "C" __declspec (dllexport)

    BOOL APIENTRY DllMain (HINSTANCE hInst /* Library instance handle. */ ,

    DWORD reason /* Reason this function is being called. */ ,

    LPVOID reserved /* Not used. */ )

    {

    switch (reason)

    {

    case DLL_PROCESS_ATTACH:
    break;
    case DLL_PROCESS_DETACH:

    break;
    case DLL_THREAD_ATTACH:

    break;
    case DLL_THREAD_DETACH:

    break;
    }

    /* return (double)s TRUE on success, FALSE on failure */

    return TRUE;

    }

    extern "C" {

    export double GM_xVideo_CaptureGetDevices(double devicetype){

    double result=0;

    if (devicetype==0){result=(double)(int) xVideo_CaptureGetDevices(xVideo_AudioCapture,&GetDevicesCallback,NULL); }

    if (devicetype==1){result= (double)(int)xVideo_CaptureGetDevices(xVideo_VideoCapture,&GetVideoDevicesCallback,NULL); }

    return(double)result;

    }

    }

    // This is only error related part of all main.cpp

    //************************************************************

    Please What to do??? Callbacks in this way don't work

    I was try to make *.def file, but i got only errors...

    Tnx in advance

  2. #2
    Join Date
    Oct 2006
    Location
    Sweden
    Posts
    3,642

    Re: How to call CALLBACK from inside DLL

    Here's a minimal example in VS2008 of doing a callback from the dll to the exe.
    Attached Files Attached Files
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  3. #3
    Join Date
    Nov 2000
    Location
    Voronezh, Russia
    Posts
    6,070

    Re: How to call CALLBACK from inside DLL

    Please What to do??? Callbacks in this way don't work
    Please explain what doesn't work. Besides, I cannot see any callback call in your code.
    Best regards,
    Igor

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