Q199516: HOWTO: Set Default Values for ActiveX Control Stock Properties
Article: Q199516
Product(s): Microsoft C Compiler
Version(s): 2.0,2.1,4.0,4.1,4.2,5.0,6.0
Operating System(s):
Keyword(s): kbnokeyword kbActiveX kbCOMt kbCtrl kbMFC kbVC200 kbVC400 kbVC500 kbVC600 kbGrpDSMFCATL
Last Modified: 11-JUN-2002
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The information in this article applies to:
- The Microsoft Foundation Classes (MFC), included with:
- Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 4.0, 4.1
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0, 6.0
- Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 5.0, 6.0
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0
- Microsoft Visual C++.NET (2002)
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NOTE: Microsoft Visual C++ NET (2002) supported both the managed code model that is provided by the .NET Framework and the unmanaged native Windows code model. The information in this article applies to unmanaged Visual C++ code only.
SUMMARY
=======
When developing an ActiveX Control, you may decide that some of the properties
should be serialized. This can be accomplished in the DoPropExchange() method of
your COleControl-derived class by using the PX_ functions. The PX_ functions
also allow you to specify a default value for the property, which is a good
programming practice. You may also want to give default values to any stock
properties that are used by your control. The serialization and initialization
of stock properties is handled by MFC in COleControl::DoPropExchange(pPX). To
set a default value for a stock property, you need to work around some of MFC's
functionality. This article explains how to do this.
MORE INFORMATION
================
Using AppWizard to generate an MFC ActiveX control project creates a
COleControl-derived class with an overridden DoPropExchange() member function.
By default, the overridden DoPropExchange() calls COleControl::DoPropExchange().
This in turn calls COleControl::ExchangeStockProps(), which contains the MFC
code for serializing stock properties.
Within this function, MFC (pre version 4.2) uses the
COleControl::m_dwStockPropMask protected member variable to determine which
stock properties you have added with Class Wizard. This mask can be modified in
your DoPropExchange() to force MFC to ignore existing stock properties and
therefore allow you to add your own code. Ideally, you should copy the relevant
code already present in COleControl::ExchangeStockProps(), and then modify it as
necessary.
In MFC version 4.2 and later, a different variable is used as the Stock Property
mask. In the following code, GetStockPropMask and SetStockPropMask hide these
differences.
The following sample code shows how to accomplish this for the Caption stock
property by modifying step three of the Circ OLE Control tutorial.
Sample Code
-----------
class CCirc3Ctrl : public COleControl
{
...
public:
void SetStockPropMask(DWORD dwStockPropMask);
DWORD GetStockPropMask();
...
}
// MANUAL CONTROL OF MAKING Caption PERSISTANT.
// To test the initialization of the caption stock property
// replace the circle3 samples DoPropExchange function with the
// following version.
// These #defines can be found in the Ctlprop.cpp file and are given
// here to remove the need to continually track them down. In the
// code, only STOCKPROP_CAPTION is used.
#define STOCKPROP_BACKCOLOR 0x00000001
#define STOCKPROP_CAPTION 0x00000002
#define STOCKPROP_FONT 0x00000004
#define STOCKPROP_FORECOLOR 0x00000008
#define STOCKPROP_TEXT 0x00000010
#define STOCKPROP_BORDERSTYLE 0x00000020
#define STOCKPROP_ENABLED 0x00000040
//**************************************************************
#define STOCKPROP_APPEARANCE 0x00000080 // New in VC 5.0
//**************************************************************
// Helper method for setting the Stock property mask.
void CCirc3Ctrl::SetStockPropMask(DWORD dwStockPropMask)
{
#if _MFC_VER >= 0x0420 // MFC version >= v4.2
*GetDispatchMap()->lpStockPropMask = dwStockPropMask;
#else // MFC version < v4.2
m_dwStockPropMask = dwStockPropMask;
#endif
}
// Helper method to Get the Stock property mask.
DWORD CCirc3Ctrl::GetStockPropMask()
{
#if _MFC_VER >= 0x0420 // MFC version >= v4.2
return COleControl::GetStockPropMask();
#else // MFC version < v4.2
return m_dwStockPropMask;
#endif
}
void CCirc3Ctrl::DoPropExchange(CPropExchange* pPX)
{
ExchangeVersion(pPX, MAKELONG(_wVerMinor, _wVerMajor));
// Need to comment out the following line since it will be <BR/>
// called later.
// COleControl::DoPropExchange(pPX);
// Handle Property Exchange of the Stock Property Caption ourselves.
BOOL bLoading = pPX->IsLoading();
CString strText;
if (!bLoading)
strText = InternalGetText();
PX_String(pPX,_T("Caption"),strText,_T("Caption"));
if (bLoading) {
TRY
SetText(strText);
END_TRY
}
// Bypass MFC's Property Exchange of the Stock Property Caption.
DWORD dwStockPropMask = GetStockPropMask();
DWORD tempMask = dwStockPropMask;
// Remove all stock property flags we are handling from tempMask.
tempMask &= ~STOCKPROP_CAPTION;
SetStockPropMask(tempMask);
// Let MFC handle any stock properties that we aren't.
COleControl::DoPropExchange(pPX);
// Reset the Stock Property Mask.
SetStockPropMask(dwStockPropMask);
if (pPX->GetVersion() == (DWORD)MAKELONG(_wVerMinor, _wVerMajor))
{
PX_Bool(pPX, _T("CircleShape"), m_circleShape, TRUE);
PX_Short(pPX, _T("CircleOffset"), m_circleOffset, 0);
PX_Long(pPX, _T("FlashColor"), (long &)m_flashColor,
RGB(0xFF, 0x00, 0x00));
PX_String(pPX, _T("Note"), m_note, _T(""));
}
else if (pPX->IsLoading())
{
// Skip over persistent data.
BOOL bDummy;
short sDummy;
long lDummy;
CString strDummy;
PX_Bool(pPX, _T("CircleShape"), bDummy, FALSE);
PX_Short(pPX, _T("CircleOffset"), sDummy, 0);
PX_Long(pPX, _T("FlashColor"), lDummy, 0);
PX_String(pPX, _T("Note"), strDummy, _T(""));
// Force property values to these defaults.
m_circleShape = TRUE;
m_circleOffset = 0;
m_flashColor = RGB(0xFF, 0x00, 0x00);
m_note = _T("");
}
}
REFERENCES
==========
The functions discussed in this article can be found using the Find in Files
feature of Visual C++. In version 2.x, search within the Cdk32\Src directory and
in version 4.x or later, search within the mfc\src subdirectory.
(c) Microsoft Corporation 1999, All Rights Reserved. Contributions by Shawn
William Karr, Microsoft Corporation.
Additional query words: 3.0 3.1 3.2 3.00 3.10 3.20 4.2 4.2b 5.0 cdk ole activex ocx initialize mfc
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Keywords : kbnokeyword kbActiveX kbCOMt kbCtrl kbMFC kbVC200 kbVC400 kbVC500 kbVC600 kbGrpDSMFCATL
Technology : kbAudDeveloper kbMFC
Version : :2.0,2.1,4.0,4.1,4.2,5.0,6.0
Issue type : kbhowto
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