How to update property values in a property page by using Visual C++ (148222)

Note Microsoft Visual C++ .NET (2002) supports both the managed code model that is provided by the Microsoft .NET Framework and the unmanaged native Microsoft Windows code model. All or part of the information in this article applies to managed Visual C++ code. You can apply this information only by using the .NET Framework. Microsoft Visual C++ 2005 supports both the managed code model that is provided by the Microsoft .NET Framework and the unmanaged native Microsoft Windows code model.

SUMMARY

To modify a property of an OLE control, you would normally change the properties value in the control's property page. However, it is possible for a property to be modifiable from more than one property page especially in development environments such as Visual Basic. In this case, when you change the property in the control's property page, you should synchronize the value in Visual Basic's Property Form. This article shows by example how to do it.

MORE INFORMATION

For example, in Visual Basic, place the Circ3 sample control on the Form page. Then click the right mouse button to select properties for the control. You will notice that the same properties can be seen in Visual Basic's Properties window. For example, one of the properties of Circ3 is the CircleOffset property. If you change this value in the Control's property page and click Apply, you will notice that the value has not been updated in Visual Basic's Properties window. To synchronize the value in both, you need to call BoundPropertyChanged(dispid) for each property you want to update.

Note The dispid is the id of the property to update. It is usually found in the header file of the COleControl-derived class. The dispids for the Circ3 control follow:

   // Dispatch and event IDs
   public:
          enum {
          //{{AFX_DISP_ID(CCirc3Ctrl)
          dispidCircleShape = 2L,
          dispidCircleOffset = 3L,
          dispidFlashColor = 1L,
          dispidNote = 4L,
          eventidClickIn = 1L,
          eventidClickOut = 2L,
          //}}AFX_DISP_ID
          };

The following sample code shows how to modify the Circ3 sample to synchronize the CircleShape and CircleOffset properties given the dispids above.

Sample code

   /* Compile options needed: none
   */ 

   void CCirc3Ctrl::OnCircleShapeChanged()
   {
      SetModifiedFlag();

      // force the control to redraw itself
      InvalidateControl();

      // reset the circle offset, if necessary
      if (m_circleShape)
         SetCircleOffset(0);

      BoundPropertyChanged(dispidCircleShape);      // *ADD THIS LINE*
   }

   void CCirc3Ctrl::SetCircleOffset(short nNewValue)
   {
      // Validate the specified offset value
      if ((m_circleOffset != nNewValue) && m_circleShape&&
          InBounds(nNewValue))
      {
         m_circleOffset = nNewValue;
         SetModifiedFlag();
         BoundPropertyChanged(dispidCircleOffset); // *ADD THIS LINE*
         InvalidateControl();
      }
   }