ScrollWindow function (winuser.h)

The ScrollWindow function scrolls the contents of the specified window's client area.

Syntax

BOOL ScrollWindow(
  [in] HWND       hWnd,
  [in] int        XAmount,
  [in] int        YAmount,
  [in] const RECT *lpRect,
  [in] const RECT *lpClipRect
);

Parameters

[in] hWnd

Type: HWND

Handle to the window where the client area is to be scrolled.

[in] XAmount

Type: int

Specifies the amount, in device units, of horizontal scrolling. If the window being scrolled has the CS_OWNDC or CS_CLASSDC style, then this parameter uses logical units rather than device units. This parameter must be a negative value to scroll the content of the window to the left.

[in] YAmount

Type: int

Specifies the amount, in device units, of vertical scrolling. If the window being scrolled has the CS_OWNDC or CS_CLASSDC style, then this parameter uses logical units rather than device units. This parameter must be a negative value to scroll the content of the window up.

[in] lpRect

Type: const RECT*

Pointer to the RECT structure specifying the portion of the client area to be scrolled. If this parameter is NULL, the entire client area is scrolled.

[in] lpClipRect

Type: const RECT*

Pointer to the RECT structure containing the coordinates of the clipping rectangle. Only device bits within the clipping rectangle are affected. Bits scrolled from the outside of the rectangle to the inside are painted; bits scrolled from the inside of the rectangle to the outside are not painted.

Return value

Type: BOOL

If the function succeeds, the return value is nonzero.

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

Remarks

If the caret is in the window being scrolled, ScrollWindow automatically hides the caret to prevent it from being erased and then restores the caret after the scrolling is finished. The caret position is adjusted accordingly.

The area uncovered by ScrollWindow is not repainted, but it is combined into the window's update region. The application eventually receives a WM_PAINT message notifying it that the region must be repainted. To repaint the uncovered area at the same time the scrolling is in action, call the UpdateWindow function immediately after calling ScrollWindow.

If the lpRect parameter is NULL, the positions of any child windows in the window are offset by the amount specified by the XAmount and YAmount parameters; invalid (unpainted) areas in the window are also offset. ScrollWindow is faster when lpRect is NULL.

If lpRect is not NULL, the positions of child windows are not changed and invalid areas in the window are not offset. To prevent updating problems when lpRect is not NULL, call UpdateWindow to repaint the window before calling ScrollWindow.

Examples

For an example, see Scrolling Text with the WM_PAINT Message.

Requirements

See also

Other Resources

RECT

Reference

ScrollDC

ScrollWindowEx

UpdateWindow