RAD Studio VCL Reference
IInterface.QueryInterface Method

Returns a reference to a specified interface if the object supports that interface.

function QueryInterface(const IID: TGUID; out Obj): HResult; stdcall;
__fastcall __stdcall HRESULT QueryInterface(const TGUID IID,  Obj);

QueryInterface checks whether the object that implements this interface supports the interface specified by IID. If so, QueryInterface  

increments the reference count. 

sets the Obj parameter so that it points to an instance of the specified interface. 

returns 0 to indicate success. 

If the object does not support the interface, QueryInterface returns a nonzero error code such as E_NoInterface. 


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