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The framework calls this member function after the window's size has changed.

afx_msg void OnSize( 
   UINT nType, 
   int cx, 
   int cy  


Specifies the type of resizing requested. This parameter can be one of the following values:

  • SIZE_MAXIMIZED   Window has been maximized.

  • SIZE_MINIMIZED   Window has been minimized.

  • SIZE_RESTORED   Window has been resized, but neither SIZE_MINIMIZED nor SIZE_MAXIMIZED applies.

  • SIZE_MAXHIDE   Message is sent to all pop-up windows when some other window is maximized.

  • SIZE_MAXSHOW   Message is sent to all pop-up windows when some other window has been restored to its former size.


Specifies the new width of the client area.


Specifies the new height of the client area.

If the SetScrollPos or MoveWindow member function is called for a child window from OnSize, the bRedraw parameter of SetScrollPos or MoveWindow should be nonzero to cause the CWnd to be repainted.


This member function is called by the framework to allow your application to handle a Windows message. The parameters passed to your function reflect the parameters received by the framework when the message was received. If you call the base-class implementation of this function, that implementation will use the parameters originally passed with the message and not the parameters you supply to the function.

// Resize the edit control contained in the view to 
// fill the entire view when the view's window is 
// resized. CMdiView is a CView derived class. 
void CMdiView::OnSize(UINT nType, int cx, int cy) 
   CView::OnSize(nType, cx, cy);
   // Resize edit to fill the whole view. 
   // OnSize can be called before OnInitialUpdate 
   // so make sure the edit control has been created. 
   if (::IsWindow(m_Edit.GetSafeHwnd()))
      m_Edit.MoveWindow (0, 0, cx, cy);

Header: afxwin.h