Q113588: FIX: Assertion, VIEWSCRL.CPP, Line 455 with SetScaleToFitSize

Article: Q113588
Product(s): Microsoft C Compiler
Version(s): winnt:
Operating System(s): 
Keyword(s): kbDocView kbMFC kbVC100bug kbVC150fix kbGrpDSMFCATLkbbuglist kbfixlist
Last Modified: 07-MAY-2001

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft Visual C++, version 1.0 
   - Microsoft Visual C++ 32-bit Edition, version 1.0 
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SYMPTOMS
========

Calling SetScaleToFitSize in OnInitialUpdate of a CFormView derived class causes
the following assertion to fail:

  File viewscrl.cpp, Line 455, Assertion Failed!

CAUSE
=====

Because the view window has not yet been displayed, SetScaleToFitSize() uses the
size of the CFormView. Because the CFormView is created with size
CRect(0,0,0,0), the view size is miscalculated.

RESOLUTION
==========

To set the view window size before calling SetScaleToFitSize, call RecalcLayout
on the parent frame. For example:

     GetParentFrame()->RecalcLayout();

See the sample code below for an example of this.

STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft Foundation Classes
(MFC) version 2.0. This problem was corrected in the Microsoft Foundation
Classes version 2.5.

MORE INFORMATION
================

The call to RecalcLayout in OnInitialUpdate is no longer needed with MFC version
2.5 because the framework takes care of calling RecalcLayout in response to the
WM_CREATE message before the call to OnInitialUpdate is made.

Sample Code
-----------

  /*  Compile options needed: none
  */ 

  void CMyFormView::OnInitialUpdate()
  {
      CFormView::OnInitialUpdate();     // Base class initialization.

      //GetParentFrame()->RecalcLayout  // Uncomment to fix. No need to
                                        // call if this is version 2.5.
      CSize mysize(100,100);

      SetScaleToFitSize(mysize);        // This will ASSERT in version
                                        // 2.0 unless RecalcLayout is
                                        // called.
  }

Additional query words: 1.00 2.00 2.10 kbNoUpdate

======================================================================
Keywords          : kbDocView kbMFC kbVC100bug kbVC150fix kbGrpDSMFCATL kbbuglist kbfixlist
Technology        : kbAudDeveloper kbMFC
Version           : winnt:
Issue type        : kbbug
Solution Type     : kbfix

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