FIX: ATL Control Does Not Size Correctly

ID: Q198019

The information in this article applies to:

The Microsoft Active Template Library (ATL) 3.0, used with:
- Microsoft Visual C++, 32-bit Editions, version 6.0

SYMPTOMS

One of the following occurs:

An ATL control appears much bigger than the specified width and height in a control container.

When you print a Web page in Internet Explorer that contains an ATL control, additional pages are printed because the control is perceived to be bigger than it actually is.

CAUSE

By default, ATL control projects have two entries in the Property Map that allow the control's display size to be persisted. These entries are:

PROP_DATA_ENTRY("_cx", m_sizeExtent.cx, VT_UI4)
PROP_DATA_ENTRY("_cy", m_sizeExtent.cy, VT_UI4)

If the control supports IPersistPropertyBagWhen, AtlIPersistPropertyBag_Load() is called when the control's properties are read in. In this function, IPropertyBag::Read() is called, but the VARIANT passed in is not initialized. Because the "vt" member of the VARIANT is set to VT_EMPTY instead of VT_UI4, in the case of "_cx" and "_cy" they are read in as some other type, which results in incorrect values.

RESOLUTION

Modify AtlIPersistPropertyBag_Load() in ATLCOM.H so that it initializes the "vt" member of the VARIANT before calling IPropertyBag::Read():


ATLINLINE ATLAPI AtlIPersistPropertyBag_Load(LPPROPERTYBAG pPropBag,

   LPERRORLOG pErrorLog, ATL_PROPMAP_ENTRY* pMap, void* pThis,
   IUnknown* pUnk)

{

   USES_CONVERSION;
   CComPtr&lt;IDispatch&gt; pDispatch;
   const IID* piidOld = NULL;
   for (int i = 0; pMap[i].pclsidPropPage != NULL; i++)
   {
      if (pMap[i].szDesc == NULL)
         continue;


      CComVariant var;
      var.vt = pMap[i].vt;     // This line needs to be added.
      ....
   }

}

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article.This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

Q194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

Q194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

MORE INFORMATION

Steps to Reproduce Behavior

Insert an ATL Control in Visual InterDev.

Click the Source tab.

Click the Design tab.

Additional query words: IPersistPropertyBagImpl Visual Basic VB IE Print Office Word Excel Access extent extents

Keywords : kbservicepack kbActiveX kbATL kbCtrlCreate kbVC600 kbVC600bug kbATL300 kbATL300bug kbVS600sp2 kbVS600SP1 kbVS600sp3fix kbGrpMFCATL
Version : WINDOWS:3.0
Platform : WINDOWS
Issue type : kbbug