Thread: Calling class function from stdcall ?

  1. #1
    Registered User
    Join Date
    Nov 2007

    Calling class function from stdcall ?

    I am quite new to c++ so please bear with me.

    I have an Adlink Angelo RTV24 video capture card, and to grab the images I need to use their c++ library.

    This function is an event callback from the card
    AngeloRTV_Set_Callback(1, MediaStreamProc);
    The event callback function looks like this
    void __stdcall MediaStreamProc(){
     // remove for space
    I am using their functions within my own class 'angeloWrapper'

    However, the MediaStreamProc function can't access any data/functions from my wrapper, as this is part of stdcall and not angeloWrapper.

    So, how can I call a function from my wrapper from within the stdcall event function? I've tried calling...
    test(); // identifier not found
    angeloWrapper::test(); // illegal call of non-static member function
    Any ideas? Many thanks

  2. #2
    Kernel hacker
    Join Date
    Jul 2007
    Farncombe, Surrey, England
    You can't use C++ functions directly as call-back functions. If the callback allows an arbitrary pointer type argument, then you can use that and cast it from & to the class pointer as needed.

    It actually isn't really to do with __stdcall, although a class-method uses the calling convention called "thiscall" because there is a hidden argument "this", representing the object itself.

    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  3. #3
    Join Date
    Oct 2007
    Inside my computer
    I'm not quite sure what or how you're doing this. Care to elaborate a little?
    Are you trying to call a class method (directly) from within the wrapper???

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