October 6, 1996

Contents

Summary

This document is a step-by-step tutorial for creating the BGSound Web design-time ActiveX control using MFC.

Create an ActiveX control

Step 1: Use MFC OLE ControlWizard to create your control

1. Create new project workspace and run OleControlWizard, creating a project named "BGSound." Set to Windowless activation in advanced options
2. Add Design-time Control SDK include directory to INCLUDE Path

   
   c:\progra~1\dcsdk\Samples\Mfc\include
   

3. Use View.ClassWizard to add Property Get/Set methods

   
   BSTR Source
   short Loop
   

4. Add Member Variables (in bgsoundctl.h)

   
   // control properties
   short m_nLoop;
   CString m_strSource;
   

5. Add Get/Set Methods (in bgsoundctl.cpp)

   
   short CBGSoundCtrl::GetLoop() 
   {
         return m_nLoop;
   }
   
   void CBGSoundCtrl::SetLoop(short nNewValue) 
   {
         // verify loop property is valid
         if (nNewValue >= -1)
         {
                // set our internal loop value
                m_nLoop = nNewValue;
   
                // notify container that a property was modified
                SetModifiedFlag();
   
                // notify property browsers that this property changed
                BoundPropertyChanged(dispidLoop);
         }
         else
         {
                ThrowError(CTL_E_INVALIDPROPERTYVALUE, 
                               _T("Loop must be an integer greater than or equal to -1"));
         }
   }
   
   BSTR CBGSoundCtrl::GetSource() 
   {
         return m_strSource.AllocSysString();
   }
   
   void CBGSoundCtrl::SetSource(LPCTSTR lpszNewValue) 
   {
       // set our internal source string
       m_strSource = lpszNewValue;
   
       // notify container that a property was modified
       SetModifiedFlag();
   
       // notify property browsers that this property changed
       BoundPropertyChanged(dispidSource);
   
       // make sure we get repainted since 'Source' is our caption
       InvalidateControl();
   }
   

6. Add Support to persist properties (in CBGSoundCtrl::DoPropExchange)

   
   // persist our properties
   PX_String(pPX, _T("Source"), m_strSource, _T(""));
   PX_Short(pPX, _T("Loop"), m_nLoop, -1);
   

7. Add Drawing Code (in CBGSoundCtrl::OnDraw)

   
   void CBGSoundCtrl::OnDraw(
                       CDC* pdc, const CRect& rcBounds, const CRect& rcInvalid)
   {
       CFont fnt;
       CRect rcText;
   
       // get text rect;
       rcText = rcBounds;
       rcText.left += 2;
       rcText.right -= 2;
       rcText.top += 2;
       rcText.bottom -= 2;
   
       // create font
       fnt.CreatePointFont(160, _T("MS Sans Serif"), pdc);
       CFont* pOldFont = pdc->SelectObject(&fnt);
       pdc->SetBkMode(TRANSPARENT);
   
       // fill our rect with gray
       pdc->FillRect(rcBounds,                                                                               CBrush::FromHandle((HBRUSH)GetStockObject(LTGRAY_BRUSH)));
   
       // draw an edge
       pdc->DrawEdge(&(RECT)rcBounds, EDGE_RAISED, BF_RECT);
   
       // draw the Source text
       pdc->DrawText(_T("\"") + m_strSource + _T("\""), &(RECT)rcText, DT_WORDBREAK | DT_CENTER); 
   
       // return to old font
       pdc->SelectObject(pOldFont);
   }
   

Add Web design-time control support

Step 2: Add IActiveDesigner interface to class definition

1. Add IActiveDesigner interface definition (in bgsoundctl.h)

   
   #include "designer.h"
   #include "webdc.h"
   

2. Declare Interface_Map and IActiveDesigner interface (in bgsoundctl.h - protected)

   
   // Interface maps
   DECLARE_INTERFACE_MAP();
   
   // IActiveDesigner Interface
   BEGIN_INTERFACE_PART(ActiveDesigner, IActiveDesigner)
      STDMETHOD(GetRuntimeClassID)(CLSID *pclsid);
      STDMETHOD(GetRuntimeMiscStatusFlags)(DWORD *dwMiscFlags);
      STDMETHOD(QueryPersistenceInterface)(REFIID riidPersist);
      STDMETHOD(SaveRuntimeState)(REFIID riidPersist, REFIID riidObjStgMed, void *pObjStgMed);
      STDMETHOD(GetExtensibilityObject)(IDispatch **ppvObjOut);
   END_INTERFACE_PART(ActiveDesigner)
   
   virtual HRESULT GetRuntimeText(CString& strText);
   

Step 3: Implement IActiveDesigner interface

1. Add intialization of IActiveDesigner GUIDs (in bgsoundctl.cpp after stdafx.h)

   
   // Define and initialize required GUIDs
   #include <initguid.h>
   #include "designer.h"
   #include "webdc.h"
   

2. Add Interface Map (in bgsoundctl.cpp)

   
   ////////////////////////////////////////////////////////////////////////
   // Interface Map
   
   BEGIN_INTERFACE_MAP(CBGSoundCtrl, COleControl)
         INTERFACE_PART(CBGSoundCtrl, IID_IActiveDesigner, ActiveDesigner)
   END_INTERFACE_MAP()
   
   

3. Add IActiveDesigner interface implementation (in bgsoundctl.cpp)

   
   ////////////////////////////////////////////////////////////////////////
   // CBGSoundCtrl::XActiveDesigner - IActiveDesigner interface
   //
   // The following functions represent the implementation of the IActiveDesigner
   // interface. For the most part, these functions can be left as is. The
   // SaveRuntimeState() function will call the CBGSoundCtrl::GetRuntimeText()
   // function when it needs to generate run-time text.
   
   STDMETHODIMP_(ULONG) CBGSoundCtrl::XActiveDesigner::AddRef(void)
   {
         METHOD_MANAGE_STATE(CBGSoundCtrl, ActiveDesigner)
         return (ULONG)pThis->ExternalAddRef();
   }
   
   STDMETHODIMP_(ULONG) CBGSoundCtrl::XActiveDesigner::Release(void)
   {
         METHOD_MANAGE_STATE(CBGSoundCtrl, ActiveDesigner)
         return (ULONG)pThis->ExternalRelease();
   }
   
   STDMETHODIMP CBGSoundCtrl::XActiveDesigner::QueryInterface(REFIID iid,
                                                                                             LPVOID far* ppvObj)
   {
         METHOD_MANAGE_STATE(CBGSoundCtrl, ActiveDesigner)
         return (HRESULT)pThis->ExternalQueryInterface(&iid, ppvObj);
   }
   
   STDMETHODIMP CBGSoundCtrl::XActiveDesigner::GetRuntimeClassID(CLSID *pclsid)
   {
       *pclsid = CLSID_NULL;
       return S_FALSE;
   }
   
   STDMETHODIMP CBGSoundCtrl::XActiveDesigner::GetRuntimeMiscStatusFlags(DWORD *pdwMiscFlags)
   {
         if (!pdwMiscFlags)
                return E_INVALIDARG;
         *pdwMiscFlags = NULL;
         return E_UNEXPECTED;
   }
   
   STDMETHODIMP CBGSoundCtrl::XActiveDesigner::QueryPersistenceInterface(REFIID riid)
   {
         if (riid == IID_IPersistTextStream)
                return S_OK;
         return S_FALSE;
   }
   
   STDMETHODIMP CBGSoundCtrl::XActiveDesigner::SaveRuntimeState
   (
         REFIID riidPersist,
         REFIID riidObjStgMed,
         void  *pObjStgMed
   )
   {
         HRESULT  hr;
         CString  cstrText;
         BSTR     bstrText;
   
         METHOD_MANAGE_STATE(CBGSoundCtrl, ActiveDesigner)
   
         if (riidPersist != IID_IPersistTextStream)
                return E_NOINTERFACE;
   
         if (riidObjStgMed != IID_IStream)
                return E_NOINTERFACE;
   
         hr = pThis->GetRuntimeText(cstrText);
         if (SUCCEEDED(hr))
         {
                bstrText = cstrText.AllocSysString();
                if (bstrText)
                {
                       hr = ((IStream *)pObjStgMed)->Write(bstrText,                                     SysStringByteLen(bstrText) + sizeof(OLECHAR), NULL);
                    SysFreeString(bstrText);
                }
                else
                    hr = E_OUTOFMEMORY;
         }
   
         return hr;
   }
   
   STDMETHODIMP CBGSoundCtrl::XActiveDesigner::GetExtensibilityObject(IDispatch **ppvObjOut)
   {
         if (!ppvObjOut)
                return E_INVALIDARG;
         return this->QueryInterface(IID_IDispatch, (void **)ppvObjOut);
   }
   
   ////////////////////////////////////////////////////////////////////////
   // CBGSoundCtrl::GetRuntimeText - Generates run-time text for the control
   //
   // GetRuntimeText() is called whenever the container needs to update the
   // run-time text after property changes or other state changes are made.
   
   HRESULT CBGSoundCtrl::GetRuntimeText(CString& strText)
   {
       // our run-time Text template
       CString strTemplate = _T("<BGSOUND SRC=\"%s\" LOOP=%d>");
   
       // format our string with our properties
         strText.Format(strTemplate, m_strSource, m_nLoop);
   
         return S_OK;
   }
   
   
   
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