GetScrollInfo The GetScrollInfo function retrieves the parameters of a scroll bar, including the minimum and maximum scrolling positions, the page size, and the position of the scroll box (thumb).BOOL GetScrollInfo( HWND hwnd, // handle to window with scroll bar int fnBar, // scroll bar flag LPSCROLLINFO lpsi // pointer to structure for scroll parameters );
Parameters hwnd Handle to a scroll bar control or a window with a standard scroll bar, depending on the value of the fnBar parameter. fnBar Specifies the type of scroll bar for which to retrieve parameters. This parameter can be one of the following values: Value Meaning SB_CTL Retrieves the parameters for a scroll bar control. The hwnd parameter must be the handle to the scroll bar control. SB_HORZ Retrieves the parameters for the given window's standard horizontal scroll bar. SB_VERT Retrieves the parameters for the given window's standard vertical scroll bar. lpsi Pointer to a SCROLLINFO structure. Before calling GetScrollInfo, set the cbSize member of the structure to sizeof(SCROLLINFO), and set the fMask member to specify the scroll bar parameters to retrieve. Before returning, the function copies the specified parameters to the appropriate members of the structure. The fMask member can be a combination of the following values: Value Meaning SIF_PAGE Copies the scroll page to the nPage member of the SCROLLINFO structure pointed to by lpsi. SIF_POS Copies the scroll position to the nPos member of the SCROLLINFO structure pointed to by lpsi. SIF_RANGE Copies the scroll range to the nMin and nMax members of the SCROLLINFO structure pointed to by lpsi. SIF_TRACKPOS Copies the current scroll box tracking position to the nTrackPos member of the SCROLLINFO structure pointed to by lpsi. Return Values If the function retrieved any values, the return value is nonzero.If the function does not retrieve any values, the return value is zero. To get extended error information, callGetLastError.Res The GetScrollInfo function enables applications to use 32-bit scroll positions. Although the messages that indicate scroll-bar position, WM_HSCROLL and WM_VSCROLL, provide only 16 bits of position data, the functions SetScrollInfo and GetScrollInfo provide 32 bits of scroll-bar position data. Thus, an application can call GetScrollInfo while processing either the WM_HSCROLL or WM_VSCROLL messages to obtain 32-bit scroll-bar position data. To get the 32-bit position of the scroll box (thumb) during a SB_THUMBTRACK notification in a WM_HSCROLL or WM_VSCROLL message, call GetScrollInfo with the SIF_TRACKPOS value in the fMask member of the SCROLLINFO structure. The function returns the tracking position of the scroll box in the nTrackPos member of the SCROLLINFO structure. This allows you to get the position of the scroll box as the user moves it. The following sample code illustrates the technique.SCROLLINFO si; case WM_HSCROLL: switch(LOWORD(wparam)) { case SB_THUMBTRACK: // Initialize SCROLLINFO structure
QuickInfo Windows NT: Requires version 3.51 or later. Windows: Requires Windows 95 or later. Windows CE: Requires version 1.0 or later. Header: Declared in winuser.h. Import Library: Use user32.lib.See Also Scroll Bars Overview, Scroll Bar Functions, SCROLLINFO, SetScrollInfo, WM_HSCROLL, WM_VSCROLL
See the link below, several samples there :http://www.codeproject.com/info/search.asp?target=getscrollinfo&st=kw&qm=adv
The GetScrollInfo function retrieves the parameters of a scroll bar, including the minimum and maximum scrolling positions, the page size, and the position of the scroll box (thumb).BOOL GetScrollInfo(
HWND hwnd, // handle to window with scroll bar
int fnBar, // scroll bar flag
LPSCROLLINFO lpsi // pointer to structure for scroll parameters
);
Parameters
hwnd
Handle to a scroll bar control or a window with a standard scroll bar, depending on the value of the fnBar parameter.
fnBar
Specifies the type of scroll bar for which to retrieve parameters. This parameter can be one of the following values: Value Meaning
SB_CTL Retrieves the parameters for a scroll bar control. The hwnd parameter must be the handle to the scroll bar control.
SB_HORZ Retrieves the parameters for the given window's standard horizontal scroll bar.
SB_VERT Retrieves the parameters for the given window's standard vertical scroll bar.
lpsi
Pointer to a SCROLLINFO structure. Before calling GetScrollInfo, set the cbSize member of the structure to sizeof(SCROLLINFO), and set the fMask member to specify the scroll bar parameters to retrieve. Before returning, the function copies the specified parameters to the appropriate members of the structure.
The fMask member can be a combination of the following values: Value Meaning
SIF_PAGE Copies the scroll page to the nPage member of the SCROLLINFO structure pointed to by lpsi.
SIF_POS Copies the scroll position to the nPos member of the SCROLLINFO structure pointed to by lpsi.
SIF_RANGE Copies the scroll range to the nMin and nMax members of the SCROLLINFO structure pointed to by lpsi.
SIF_TRACKPOS Copies the current scroll box tracking position to the nTrackPos member of the SCROLLINFO structure pointed to by lpsi. Return Values
If the function retrieved any values, the return value is nonzero.If the function does not retrieve any values, the return value is zero. To get extended error information, callGetLastError.Res
The GetScrollInfo function enables applications to use 32-bit scroll positions. Although the messages that indicate scroll-bar position, WM_HSCROLL and WM_VSCROLL, provide only 16 bits of position data, the functions SetScrollInfo and GetScrollInfo provide 32 bits of scroll-bar position data. Thus, an application can call GetScrollInfo while processing either the WM_HSCROLL or WM_VSCROLL messages to obtain 32-bit scroll-bar position data. To get the 32-bit position of the scroll box (thumb) during a SB_THUMBTRACK notification in a WM_HSCROLL or WM_VSCROLL message, call GetScrollInfo with the SIF_TRACKPOS value in the fMask member of the SCROLLINFO structure. The function returns the tracking position of the scroll box in the nTrackPos member of the SCROLLINFO structure. This allows you to get the position of the scroll box as the user moves it. The following sample code illustrates the technique.SCROLLINFO si;
case WM_HSCROLL:
switch(LOWORD(wparam)) {
case SB_THUMBTRACK:
// Initialize SCROLLINFO structure
ZeroMemory(&si, sizeof(SCROLLINFO));
si.cbSize = sizeof(SCROLLINFO);
si.fMask = SIF_TRACKPOS;
// Call GetScrollInfo to get current tracking
// position in si.nTrackPos
if (!GetScrollInfo(hwnd, SB_HORZ, &si) )
return 1; // GetScrollInfo failed
break;
.
.
.
}
QuickInfo
Windows NT: Requires version 3.51 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winuser.h.
Import Library: Use user32.lib.See Also
Scroll Bars Overview, Scroll Bar Functions, SCROLLINFO, SetScrollInfo, WM_HSCROLL, WM_VSCROLL