PRB: Flicker in ATL Controls When Resized

• The Microsoft Active Template Library (ATL), versions 2.0, 2.1, 3.0, used with:
  • Microsoft Visual C++, 32-bit Editions, versions 4.2, 5.0, 6.0

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

Keywords : kbnokeyword kbActiveX kbATL200 kbATL210 kbCOMt kbCtrlCreate kbGDI kbVC420 kbVC500 kbVC600 kbATL300 kbGrpMFCATL
Version : WINDOWS:2.0,2.1,3.0
Platform : WINDOWS
Issue type : kbprb