GameMaker Studio, Create Async Event from Windows DLL

Question

I'm trying to fire a Social Asynchronous event from a DLL on Windows. There is a tutorial for this here at the bottom.

What I don't understand is the following

When your extension is loaded this callback should fire immediately and be passed in pointers to the four functions.

I guess I should call the function (RegisterCallbacks) from GML since the callback is defined as dllexport.

Here's the callback function

__declspec (dllexport) void RegisterCallbacks(char *arg1, char *arg2, char *arg3, char *arg4 )
{
    void (*CreateAsynEventWithDSMapPtr)(int,int) = (void (*)(int,int))(arg1);
    int(*CreateDsMapPtr)(int _num,...) = (int(*)(int _num,...)) (arg2); 
    CreateAsynEventWithDSMap = CreateAsynEventWithDSMapPtr;
    CreateDsMap = CreateDsMapPtr;

    bool (*DsMapAddDoublePtr)(int _index,char *_pKey,double value)= (bool(*)(int,char*,double))(arg3);
    bool (*DsMapAddStringPtr)(int _index, char *_pKey, char *pVal)= (bool(*)(int,char*,char*))(arg4);

    DsMapAddDouble = DsMapAddDoublePtr;
    DsMapAddString = DsMapAddStringPtr;
}

But how should I pass a pointer to "CreateAsynEventWithDSMap" from GML? Where do I get those functions?

score 1 · Accepted Answer · answered Jan 23 '17 at 17:21

Old question, but I recently had this problem myself and spent a couple of days scratching my head, so I thought I'd post the answer for the record.

First of all the RegisterCallbacks function in the DLL needs to be __declspec (dllexport) and also extern "C", like any other function exported to GM.

Second, the RegisterCallbacks function should be defined in GM also, not just in the C/C++ file, again just like any other exported function in the extension. The four arguments should be defined as string type. It should look like this: https://i.stack.imgur.com/FiHjV.png

Now, RegisterCallbacks should fire automatically when you start your game, and the DsMap functions to do async stuff should work. Do not try to call RegisterCallbacks() manually.

GameMaker Studio, Create Async Event from Windows DLL

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