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.
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...
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:
There's also DECLARE_MESSAGE_MAP() and DECLARE_EVENT_MAP() though, which might be about what you want also.