This function sets the position of the scroll box (thumb) in the specified scroll bar and, if requested, redraws the scroll bar to reflect the new position of the scroll box. SetScrollPos is provided for compatibility with Windows 3.x. Win32-based applications should use the SetScrollInfo function.
At a Glance
| Header file: | Winuser.h |
| Windows CE versions: | 2.0 and later |
Syntax
int SetScrollPos( HWND hWnd, int nBar, int nPos, BOOL bRedraw);
Parameters
hWnd
Handle to a scroll bar control or a window with a standard scroll bar, depending on the value of the nBar parameter.
nBar
Specifies the scroll bar to be set. This parameter can be one of the following values:
| Value | Description |
| SB_CTL | Sets the position of the scroll box in a scroll bar control. The hWnd parameter must be the handle to the scroll bar control. |
| SB_HORZ | Sets the position of the scroll box in a window’s standard horizontal scroll bar. |
| SB_VERT | Sets the position of the scroll box in a window’s standard vertical scroll bar. |
nPos
Specifies the new position of the scroll box. The position must be within the scrolling range. For more information about the scrolling range, see the SetScrollRange function.
bRedraw
Boolean that specifies whether the scroll bar is redrawn to reflect the new scroll box position. If this parameter is TRUE, the scroll bar is redrawn. If it is FALSE, the scroll bar is not redrawn.
Return Values
The previous position of the scroll box indicates success. Zero indicates failure. To get extended error information, call GetLastError.
Remarks
If the scroll bar is redrawn by a subsequent call to another function, setting the bRedraw parameter to FALSE is useful.
Because the messages that indicate scroll bar position, WM_HSCROLL and WM_VSCROLL, are limited to 16 bits of position data, applications that rely solely on those messages for position data have a practical maximum value of 65,535 for the SetScrollPos function’s nPos parameter.
However, because the SetScrollInfo, SetScrollPos, SetScrollRange, GetScrollInfo, GetScrollPos, and GetScrollRange functions support 32-bit scroll bar position data, there is a way to circumvent the 16-bit barrier of the WM_HSCROLL and WM_VSCROLL messages. See GetScrollInfo for a description of the technique.
See Also