Microsoft KB Archive/166135

= Changes in Print Preview behavior since Visual C++ 4.2 =

Article ID: 166135

Article Last Modified on 6/3/2005

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APPLIES TO


 * Microsoft Visual C++ 4.2 Enterprise Edition
 * Microsoft Visual C++ 4.2 Enterprise Edition
 * Microsoft Visual C++ 5.0 Enterprise Edition
 * Microsoft Visual C++ 6.0 Enterprise Edition
 * Microsoft Visual C++ 4.2 Professional Edition
 * Microsoft Visual C++ 4.2 Professional Edition
 * Microsoft Visual C++ 5.0 Professional Edition
 * Microsoft Visual C++ 6.0 Professional Edition
 * Microsoft Visual C++ 6.0 Standard Edition

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This article was previously published under Q166135





SYMPTOMS
When you display Print Preview for a Multiple Document Interface (MDI) application, depending on the version of Microsoft Foundations Classes (MFC) you are using, it may appear either in the MDI child frame or in the MDI main frame. For Visual C++ 4.2b, it is further dependent on whether you have a splitter window or not.



CAUSE
The preview window was moved to the MDI child window to support ActiveX documents. However, it was later decided that keeping it in the MDI main frame window was the better design choice.



RESOLUTION
Statically link to the MFC libraries (modified or unmodified) or design your preview function using the latest behavior in Visual C++ 6.0.



STATUS
Microsoft has confirmed this to be a bug only in the MFC libraries in Visual C++ 4.2b and 5.0.

This problem was corrected in Visual C++ 6.0.



MORE INFORMATION
When MFC's Print Preview is invoked, it searches for the frame window of the current view using GetParentFrame to display the preview view. This is done in CView::DoPrintPreview. The code below reflects some of the changes that DoPrintPreview went through between Visual C++ versions 4.2 and 6.0:

Visual C++ 4.2
In Visual C++ 4.2, Print Previews always appear in the MDI frame window. This was the original behavior. // VC 4.2 BOOL CView::DoPrintPreview(UINT nIDResource, CView* pPrintView, CRuntimeClass* pPreviewViewClass, CPrintPreviewState* pState) {   ...    CFrameWnd* pParent = (CFrameWnd*)AfxGetThread->m_pMainWnd; ASSERT_VALID(pParent); ASSERT_KINDOF(CFrameWnd, pParent);

Visual C++ 4.2b
In Visual C++ 4.2b, Print Preview was moved to the MDI child frame to support Active Documents. However, it appears in the MDI frame window only when the parent of the view is not a CFrameWnd-derived object (such as a splitter window). This inconsistency was considered a bug and was fixed in Visual C++ 5.0. // VC 4.2b BOOL CView::DoPrintPreview(UINT nIDResource, CView* pPrintView,   CRuntimeClass* pPreviewViewClass, CPrintPreviewState* pState) {   ...    CFrameWnd* pParent; CWnd* pNaturalParent = pPrintView->GetParent; pParent = DYNAMIC_DOWNCAST(CFrameWnd, pNaturalParent); if (pParent == NULL) pParent = (CFrameWnd*)AfxGetThread->m_pMainWnd;

Visual C++ 5.0
In VC 5.0, Print Preview always appears within the MDI child window. (This was the intended "feature" in Visual C++ 4.2b.) // VC 5.0 BOOL CView::DoPrintPreview(UINT nIDResource, CView* pPrintView,  CRuntimeClass* pPreviewViewClass, CPrintPreviewState* pState) {  ...   CFrameWnd* pParent; CWnd* pNaturalParent = pPrintView->GetParentFrame; pParent = DYNAMIC_DOWNCAST(CFrameWnd, pNaturalParent); if (pParent == NULL || pParent->IsIconic) pParent = (CFrameWnd*)AfxGetThread->m_pMainWnd;

Visual C++ 6.0
For Visual C++ 6.0, Microsoft decided that Print Preview belongs in the MDI main frame window, so its behavior was changed back. (The Visual C++ 5.0 "feature" was considered a bug.) BOOL CView::DoPrintPreview(UINT nIDResource, CView* pPrintView,   CRuntimeClass* pPreviewViewClass, CPrintPreviewState* pState) {   ...    CFrameWnd* pParent = STATIC_DOWNCAST(CFrameWnd, AfxGetMainWnd); ASSERT_VALID(pParent); To change the behavior of Print Preview in any of the versions, you have to modify the MFC sources and rebuild the MFC libraries. It is not possible to override DoPrintPreview in your CView-derived class because it requires the use of protected members of friend classes.

The best design approach is to write your application using the behavior where Print Preview appears within the MDI main frame window. This is the current behavior of MFC.

Keywords: kbtshoot kbbug kbfix kbnoupdate kbprint kbuidesign kbvc600fix kbdocview kbcode KB166135

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