I can use VS08's MFC/ActiveX template to create a C++ ActiveX object that I can load into a HTML page and script with Javascript. But I can't figure out how to create an interface that allows me to call custom methods on my component with Javascript.
Could you please tell me how to accomplish that? I have spent over two hours on google with no luck.
Thanks.
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I'm not extremely familiar with the MFC ActiveX wrapper, but I can answer the question in the general sense:
A COM object with an interface which is derived from IDispatch can be called through automation languages (eg: Javascript). The methods must also be "automation-compatible", which means that the parameters are convertible to the VARIANT type, or are explicitly of type VARIANT. Note that for in/out parameters, the type must be VARIANT* for the automation "hookup" to work.
I don't know how to make the ActiveX object accessible in the client script (eg: embed it into the page), but if it has a single interface derived from IDispatch, that makes it callable from Javascript (and other automation languages). I hope that helps...
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This works for embedding your ActiveX container in an html page and invoking a method:
<html> <body> <object height="0" width="0" id="myControl" classid="CLSID:AC12D6F8-AEB7-4935-B3C9-0E4FB6CF7FB1" type="application/x-oleobject"> </object> <script> var activexObj = document.getElementById('myControl'); if(activexObj != null) { var result = myControl.myMethod(); document.write("Result: " + result + "<br/>"); } else { document.write("ActiveX component not found!<br/>"); } </script> </body> </html> -
If you're using the VS08 MFC ActiveX template, you might see a snippet like this in your control's .h file (within the class declaration, it's protected):
afx_msg void AboutBox(); DECLARE_DISPATCH_MAP()And one like this in the .cpp file:
// Dispatch map BEGIN_DISPATCH_MAP(CActiveXOutlookCtrl, COleControl) DISP_FUNCTION_ID(yourCtrl, "AboutBox", DISPID_ABOUTBOX, AboutBox, VT_EMPTY, VTS_NONE) END_DISPATCH_MAP()I've never had to use this, but this is your dispatch interface - aka the methods on your object others can call. What it means:
- "AboutBox" is the name they use to call it.
- DISPID_ABOUTBOX is an integer id for the function (I think it's arbitrary. I'd use a positive number because a lot of negatives are taken by default).
- AboutBox is the method name.
- VT_EMPTY is the method's return type.
- VTS_NONE is the type of params it takes.
There's also DECLARE_MESSAGE_MAP() and DECLARE_EVENT_MAP() though, which might be about what you want also.
Comptrol : one trivial correction, DECLARE_DISPATCH_MAP() should follow the function declaration.
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