HOWTO: Setting the Picture Property of an ActiveX Control

• Microsoft Visual C++, 32-bit Editions, versions 4.0, 5.0, 6.0

SUMMARY

To set the Picture property of an ActiveX control, you can use the Component Gallery to insert an ActiveX control into an AppWizard-generated application with control container support. If the control has a picture property, the wrapper classes generated by the Component Gallery will contain the SetPicture() and GetPicture() methods. The More Information section below contains details that explain how to use the picture property of an ActiveX control.

MORE INFORMATION

Using the Grid Control (Grid32.ocx is shipped with Visual C++ 4.x) as an example, you can implement the SetPicture() and GetPicture() methods in the control classes provided by the Component Gallery by using this code:

   void CGridCtrl::SetPicture(LPDISPATCH propVal)
   {
        SetProperty(0x15, VT_DISPATCH, propVal);
   }

   CPicture CGridCtrl::GetPicture()
   {
        LPDISPATCH pDispatch;
        GetProperty(0x15, VT_DISPATCH, (void*)&pDispatch);
        return CPicture(pDispatch);
   } 

1. Generate a new non-dialog based AppWizard application. Be sure to select both Container and Control support in AppWizard Step 3.



2. Add the Grid Control from the OLE Controls tab (or Registered ActiveX Controls in VC++ 5.0) in the Component Gallery.



3. Add Afxctl.h to the list of pre-compiled header files in Stdafx.h.



4. Add a Grid Control object to the About Dialog box in the dialog editor.



5. Using ClassWizard, add a control member variable called m_grid to the Grid Control in the About Dialog box.



6. Override the container's initialization routine to create and initialize a CPictureHolder object. Call the SetPicture() method for the control, passing in the CPictureHolder's dispatch pointer. SetPicture calls SetProperty() for the control. Here's an example:

   
         BOOL CAboutDlg::OnInitDialog()
         {
             CDialog::OnInitDialog();
   
             // Create and Initialize the CPictureHolder variable with the
             // toolbar resource
             CPictureHolder pictholder;
             pictholder.CreateFromBitmap(IDR_MAINFRAME);
   
             //Pass dispatch pointer to CPictureHolder
             m_grid.SetPicture(pictholder.GetPictureDispatch());
   
             // NOTE: GetPictureDispatch() QI()'s for the IPictureDisp
             // interface, so the picture object will remain alive until
             // the property is reset or the control is destroyed. When
             // pictholder goes out of scope, it calls Release() on the
             // picture object, but the previously mentioned QI() will have
             // bumped the ref count, allowing it to remain alive until the
             // control itself releases the picture object.
   
           return TRUE;
         } 

REFERENCES

For Visual C++ 4.xx: OLE Control Containers: Programming OLE Controls in an OLE Control Container - Visual C++ Books Online, MFC Encyclopedia.

OLE Controls: Using Pictures in an OLE Control - Visual C++ Books Online, MFC Encyclopedia.

For Visual C++ 5.0: ActiveX Control Containers: Programming ActiveX Controls in an ActiveX Control Container - Visual C++ Books Online, Visual C++ Programmer's Guide.

ActiveX Controls: Using Pictures in an ActiveX Control - Visual C++ Books Online, Visual C++ Programmer's Guide.

Additional query words: ocx

Keywords : kbcode kbole kbCtrl kbMFC kbVC400 kbVC500 kbVC600
Version : 4.0 5.0 6.0
Platform : NT WINDOWS
Issue type : kbhowto