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 SetScrollInfo

The SetScrollInfo function sets the parameters of a scroll bar, including the minimum and maximum scrolling positions, the page size, and the position of the scroll box (thumb). The function also redraws the scroll bar, if requested.

Syntax

    int SetScrollInfo(  
        HWND hwnd,
        int fnBar,
        LPCSCROLLINFO lpsi,
        BOOL fRedraw
    );

Parameters

• hwnd
  [in] Handle to a scroll bar control or a window with a standard scroll bar, depending on the value of the fnBar parameter.
• fnBar
  [in] Specifies the type of scroll bar for which to set parameters. This parameter can be one of the following values.
  • SB_CTL
    Sets the parameters of a scroll bar control. The hwnd parameter must be the handle to the scroll bar control.
  • SB_HORZ
    Sets the parameters of the window's standard horizontal scroll bar.
  • SB_VERT
    Sets the parameters of the window's standard vertical scroll bar.
• lpsi
  [in] Pointer to a SCROLLINFO structure. Before calling SetScrollInfo, set the cbSize member of the structure to sizeof(SCROLLINFO), set the fMask member to indicate the parameters to set, and specify the new parameter values in the appropriate members. The fMask member can be one or more of the following values.
  • SIF_DISABLENOSCROLL
    Disables the scroll bar instead of removing it, if the scroll bar's new parameters make the scroll bar unnecessary.
  • SIF_PAGE
    Sets the scroll page to the value specified in the nPage member of the SCROLLINFO structure pointed to by lpsi.
  • SIF_POS
    Sets the scroll position to the value specified in the nPos member of the SCROLLINFO structure pointed to by lpsi.
  • SIF_RANGE
    Sets the scroll range to the value specified in the nMin and nMax members of the SCROLLINFO structure pointed to by lpsi.
• fRedraw
  [in] Specifies whether the scroll bar is redrawn to reflect the changes to the scroll bar. If this parameter is TRUE, the scroll bar is redrawn, otherwise, it is not redrawn.

Return Value

The return value is the current position of the scroll box.

Remarks

The SetScrollInfo function performs range checking on the values specified by the nPage and nPos members of the SCROLLINFO structure. The nPage member must specify a value from 0 to nMax - nMin +1. The nPos member must specify a value between nMin and nMax - max( nPage– 1, 0). If either value is beyond its range, the function sets it to a value that is just within the range.

If the fnBar parameter is SB_CTL and the window specified by the hwnd parameter is not a system scroll bar control, the system sends the SBM_SETSCROLLINFO message to the window to set scroll bar information (The system can optimize the message to SBM_SETPOS or SBM_SETRANGE if the request is solely for the position or range). This allows SetScrollInfo to operate on a custom control that mimics a scroll bar. If the window does not handle SBM_SETSCROLLINFO (or the optimized SBM_SETPOS message or SBM_SETRANGE message), then the SetScrollInfo function fails.

Function Information

• Minimum DLL Version user32.dll
• Header Declared in Winuser.h, include Windows.h
• Import library User32.lib
• Minimum operating systems Windows 95, Windows NT 3.51

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