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 win32 msgs: WM_SETREDRAW

An application sends the WM_SETREDRAW message to a window to allow changes in that window to be redrawn or to prevent changes in that window from being redrawn.

To send this message, call the SendMessage function with the following parameters.

    SendMessage( 
      (HWND) hWnd,              // handle to destination window 
      WM_SETREDRAW,             // message to send
      (WPARAM) wParam,          // redraw state
      (LPARAM) lParam           // not used; must be zero
    );

Parameters

• wParam
Specifies the redraw state. If this parameter is TRUE, the content can be redrawn after a change. If this parameter is FALSE, the content cannot be redrawn after a change.
• lParam
This parameter is not used.

Return Values

An application returns zero if it processes this message.

Remarks

This message can be useful if an application must add several items to a list box. The application can call this message with wParam set to FALSE, add the items, and then call the message again with wParam set to TRUE. Finally, the application can call the InvalidateRect function to cause the list box to be repainted.

Requirements

• Windows NT/2000/XP/Vista: Included in Windows NT 3.1 and later.
• Windows 95/98/Me: Included in Windows 95 and later.
• Header: Declared in Winuser.h; include Windows.h.

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Notebook exported on Monday, 7 July 2008, 18:56:50 PM Eastern Daylight Time