Q183210: PRB: Flicker in ATL Controls When Resized

Article: Q183210
Product(s): Microsoft C Compiler
Version(s): 2.0,2.1,3.0,4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbnokeyword kbActiveX kbATL200 kbATL210 kbCOMt kbCtrlCreate kbGDI kbVC420 kbVC500 kbVC6
Last Modified: 13-JUN-2002

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The information in this article applies to:

- The Microsoft Active Template Library (ATL), versions 2.0, 2.1, 3.0, used with:
   - 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 Windows XP Home Edition 
   - Microsoft Windows XP Professional 
   - Microsoft Visual C++.NET (2002) 
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SYMPTOMS
========

An ATL control might flicker while it is being resized. For example, if you have
a ListView control inside an ATL control and you allow it to be resized at run
time, a significant amount of flickering occurs.

CAUSE
=====

ATL controls are created by default with the CS_HREDRAW and CS_VREDRAW class
styles. These styles cause the entire window to be redrawn when the window is
resized.

RESOLUTION
==========

Remove the CS_HREDRAW and CS_VREDRAW styles from the window by overriding the
GetWndClassInfo() function. Add the following function to your
CComControl-derived class:

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

  static CWndClassInfo& GetWndClassInfo()
  {
     static CWndClassInfo wc = {{ sizeof(WNDCLASSEX), 0, StartWindowProc,
     0, 0, 0, 0, 0, (HBRUSH)(COLOR_WINDOW+1), 0, "MyControlClass", 0 },
     NULL, NULL, IDC_ARROW, TRUE, 0, _T("")};
     return wc;
  }

STATUS
======

This behavior is by design.

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

GetWndClassInfo() is called by the CWindowImpl<>::Create() method during
window creation and uses the WNDCLASS structure initialized by
GetWndClassInfo().

Additional query words: WM_PAINT OnPaint OnDraw WM_SIZE OnSize SetObjectRects Invalidate InvalidateRect FireViewChange kbATL200 kbATL210 kbATL300 kbctrl

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Keywords          : kbnokeyword kbActiveX kbATL200 kbATL210 kbCOMt kbCtrlCreate kbGDI kbVC420 kbVC500 kbVC600 kbATL300 kbGrpDSMFCATL 
Technology        : kbVCsearch kbAudDeveloper kbATLsearch kbVCNET
Version           : :2.0,2.1,3.0,4.2,5.0,6.0
Issue type        : kbprb

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