HOWTO: Detect IE's STOP Button Click in ActiveX Control

• The Microsoft Foundation Classes (MFC) included with: - Microsoft Visual C++, 32-bit Editions, versions 4.2, 4.2b, 5.0

SUMMARY

For some ActiveX controls, such as ActiveMovie, the STOP button in the toolbar of the Internet Explorer has special meaning to them. Those controls may want to stop playing the background sound or movie when the STOP button is clicked. This article shows how to add the IOleCommandTarget interface to an ActiveX control to trap the STOP button selection.

MORE INFORMATION

ActiveX controls typically do not support the IOleCommandTarget interface. For ActiveX controls that support IOleCommandTarget interface, you must add the following code to the .h and .cpp files of the COleControl-derived class. Then, you can trap the OLECMDID_STOP command id (id for the STOP button in Internet Explorer's toolbar) in the IOleCommandTarget::Exec() function.

   // In the .h file of COleControl-derived class:
   class CMyOleControl : public COleControl
   {
      ...

   // Interface Maps
   protected:

      // Add the following to support the IOleCommandTarget interface.
      // NOTE:  Nested class name is called CmdTargetObj
      DECLARE_INTERFACE_MAP()

      BEGIN_INTERFACE_PART(CmdTargetObj, IOleCommandTarget)
         STDMETHOD(QueryStatus)(const GUID*, ULONG, OLECMD[], OLECMDTEXT*);
         STDMETHOD(Exec)(const GUID*, DWORD, DWORD, VARIANTARG*,
            VARIANTARG*);
      END_INTERFACE_PART(CmdTargetObj)
   };


   // In the .cpp file of COleControl-derived class:
   BEGIN_INTERFACE_MAP(CMyOleControl, COleControl)
      INTERFACE_PART(CMyOleControl, IID_IOleCommandTarget, CmdTargetObj)
   END_INTERFACE_MAP()

   ULONG FAR EXPORT CMyOleControl::XCmdTargetObj::AddRef()
   {
      METHOD_PROLOGUE(CMyOleControl, CmdTargetObj)
      return pThis->ExternalAddRef();
   }

   ULONG FAR EXPORT CMyOleControl::XCmdTargetObj::Release()
   {
      METHOD_PROLOGUE(CMyOleControl, CmdTargetObj)
      return pThis->ExternalRelease();
   }

   HRESULT FAR EXPORT CMyOleControl::XCmdTargetObj::QueryInterface(
      REFIID iid, void FAR* FAR* ppvObj)
   {
      METHOD_PROLOGUE(CMyOleControl, CmdTargetObj)
      return (HRESULT)pThis->ExternalQueryInterface(&iid, ppvObj);
   }

   STDMETHODIMP CMyOleControl::XCmdTargetObj::QueryStatus(
      const GUID* pguidCmdGroup, ULONG cCmds, OLECMD rgCmds[],
      OLECMDTEXT* pcmdtext)
   {
      METHOD_PROLOGUE(CMyOleControl, CmdTargetObj)
      //... add YOUR own code here.

      return S_OK;
   }

   STDMETHODIMP CMyOleControl::XCmdTargetObj::Exec(
      const GUID* pguidCmdGroup, DWORD nCmdID, DWORD nCmdExecOpt,
      VARIANTARG* pvarargIn, VARIANTARG* pvarargOut)
   {
      METHOD_PROLOGUE(CMyOleControl, CmdTargetObj)
      if (nCmdID == OLECMDID_STOP)
         {
         // ... STOP button is clicked, add YOUR own code here.
         // We just display a message box.
         ::MessageBox(NULL, "STOP","CMyOleControl", MB_OK);
         }

      return S_OK;
   }

REFERENCES

This article only focuses on the STOP button selection. For additional information about other buttons selection, please see the following article(s) in the Microsoft Knowledge Base:

   ARTICLE-ID: Q167230
   TITLE     : HOWTO: Detecting when IE holds Controls and Pages in Memory

(c) Microsoft Corporation 1997, All Rights Reserved. Contributions by Yeong-Kah Tam, Microsoft Corporation