IMyInterface = interface(IInterface) ['{63E072DF-B81E-4734-B3CB-3C23C7FDA8EA}'] function F1 : Integer; stdcall; end; TFooBar = class(TBaseProperty, IMyInterface) function F1 : Integer; virtual; stdcall; protected FRefCount: Integer; function QueryInterface(const IID: TGUID; out Obj): HResult; stdcall; function _AddRef: Integer; stdcall; function _Release: Integer; stdcall; end; TFooBar1 = class(TFooBar) function F1: Integer; override; stdcall; end;
procedure TForm1.Button2Click(Sender: TObject); var a: TFooBar; dd: IMyInterface; begin a := TFooBar1.Create; if a.GetInterface(IMyInterface, dd) then Memo1.Lines.Add(IntToStr(dd.F1)); end;
function TFooBar.QueryInterface(const IID: TGUID; out Obj): HResult; const E_NOINTERFACE = HResult($80004002); begin if GetInterface(IID, Obj) then Result := 0 else Result := E_NOINTERFACE; end; function TFooBar._AddRef: Integer; begin INC(FRefCount); // ShowMessage(Format('Increase reference count to %d.', [FRefCount])); result:=FRefCount; end; function TFooBar._Release: Integer; begin DEC(FRefCount); if FRefCount <> 0 then // ShowMessage(Format('Decrease reference count to %d.', [FRefCount])) else begin Destroy; // ShowMessage('Decrease reference count to 0, and destroy the object.'); end; result:=FRefCount; end;