PRB: Appearance Property Uses Windows 4.0 WS_EX_CLIENTEDGE

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This article was previously published under Q152000

SYMPTOMS

MFC Controls support a set of standard properties. One of these properties is Appearance (DISPID_APPEARANCE). Appearance is implemented to give a control a 3-D look. If the control is used on a version of Windows or Windows NT less than 4.0, the Appearance property will not affect the appearance of the control at run time.

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CAUSE

At run time, the Appearance property is implemented in an MFC control by setting an extended window style WS_EX_CLIENTEDGE. This window style is not supported on versions of Windows or Windows NT less than 4.0.

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RESOLUTION

It is possible to supply your own implementation of the Appearance property although this technique will not work for subclassed Windows controls.

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STATUS

This behavior is by design.

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MORE INFORMATION

Using the Class Wizard, add the stock Appearance property but choose Get/Set methods rather that accepting the stock implementation. In the control, declare a member variable of type BOOL to represent the Appearance property. The stock Get/Set functions can be copied and changed slightly to manipulate this variable as well as handle the property binding requirements. In the Draw function, draw a 3-D border depending on the value of this variable.

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Sample Code

   // these get and set functions are the same as the original with a minor
   // change (noted in the code)

   short CTestAppearanceCtrl::GetAppearance()
   {
       return m_MyAppearance;
   }

   void CTestAppearanceCtrl::SetAppearance(short nNewValue)
   {
       if (nNewValue != 0 && nNewValue != 1)
           ThrowError(CTL_E_INVALIDPROPERTYVALUE,
                      AFX_IDP_E_INVALIDPROPERTYVALUE);

       // Is the property changing?
       if (m_MyAppearance == nNewValue)
           return;

       if (!BoundPropertyRequestEdit(DISPID_APPEARANCE))
           SetNotPermitted();

   // changed from original
       // do not use the WS_EX_CLIENTEDGE style
       //ASSERT((m_hWnd == NULL) ||
       //  ((GetExStyle() & WS_EX_CLIENTEDGE) == (DWORD)(m_sAppearance ?
       //      WS_EX_CLIENTEDGE : 0)));

       m_MyAppearance = nNewValue;
       SetModifiedFlag();

       //ToggleAppearance(this);
   // end of changes

       OnAppearanceChanged();

       BoundPropertyChanged(DISPID_APPEARANCE);
   }

   void CTestAppearanceCtrl::OnDraw(
               CDC* pdc, const CRect& rcBounds, const CRect& rcInvalid)
   {
       // TODO: Replace the following code with your own drawing code.
       pdc->FillRect(rcBounds,
            CBrush::FromHandle((HBRUSH)GetStockObject(WHITE_BRUSH)));
       pdc->Ellipse(rcBounds);

       // draw as 3D if m_appearance is set

       if(m_appearance)
       {
           CRect rect(rcBounds);
           pdc->DrawEdge(rect, EDGE_SUNKEN, BF_RECT | BF_ADJUST);
       }
   }

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APPLIES TO

Microsoft Foundation Class Library 4.2, when used with:

Microsoft Visual C++ 4.0 Standard Edition
Microsoft Visual C++ 4.1 Subscription

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kbctrlcreate kbprb kbuidesign KB152000

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Retired KB Content Disclaimer

This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.

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