GetScrollPos EG629S

The GetScrollPos function retrieves the current position of the scroll box (thumb) in the specified scroll bar. The current position is a relative value that depends on the current scrolling range. For example, if the scrolling range is 0 through 100 and the scroll box is in the middle of the bar, the current position is 50.

int GetScrollPos(

HWND hWnd,	// handle of window with scroll bar
int nBar	// scroll bar flags
);

Parameters

hWnd

Identifies 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 examined. This parameter can be one of the following values:

Value	Meaning
SB_CTL	Retrieves the position of the scroll box in a scroll bar control. The hWnd parameter must be the handle of the scroll bar control.
SB_HORZ	Retrieves the position of the scroll box in a window s standard horizontal scroll bar.
SB_VERT	Retrieves the position of the scroll box in a window s standard vertical scroll bar.

Return Values

If the function succeeds, the return value is the current position of the scroll box/

If the function fails, the return value is zero. To get extended error information, call GetLastError11C2VS7.

Remarks

The GetScrollPos function enables applications to use 32-bit scroll positions. Although the messages that indicate scroll bar position, WM_HSCROLL and WM_VSCROLL, are limited to 16 bits of position data, the functions SetScrollPos3.EU_8, SetScrollRange2VV40LI, GetScrollPos, and GetScrollRange8I2XX2 support 32-bit scroll bar position data. Thus, an application can call GetScrollPos while processing either the WM_HSCROLLE_2M08 or WM_VSCROLL1I8PUW5 messages to obtain 32-bit scroll bar position data.

The limitation on this technique applies to real-time scrolling of a window s content. An application implements such scrolling by processing the WM_HSCROLL or WM_VSCROLL messages that carry the SB_THUMBTRACK notification message, thereby tracking the position of the scroll box, also known as the thumb, while the user moves it. Unfortunately, there is no function to retrieve the thumb s 32-bit position while the user moves it. GetScrollPos provides static position data only; an application can therefore only obtain 32-bit position data before or after a scroll has taken place.