ScrollDC

A version of this page is also available for

Windows Embedded CE 6.0 R3

4/8/2010

This function scrolls a rectangle of bits horizontally and vertically.

Syntax

BOOL ScrollDC(
  HDC hDC, 
  int dx, 
  int dy, 
  const RECT* lprcScroll, 
  const RECT* lprcClip, 
  HRGN hrgnUpdate, 
  LPRECT lprcUpdate 
); 

Parameters

• hDC
  [in] Handle to the device context that contains the bits to be scrolled.

• dx
  [in] Specifies the amount, in device units, of horizontal scrolling.

  This parameter must be a negative value to scroll to the left.

• dy
  [in] Specifies the amount, in device units, of vertical scrolling.

  This parameter must be a negative value to scroll up.

• lprcScroll
  [in] Long pointer to the RECT structure containing the coordinates of the scrolling rectangle.

  The only bits affected by the scroll operation are bits in the intersection of this rectangle and the rectangle specified by lprcClip.

  If lprcScroll is NULL, the entire client area is used.

• lprcClip
  [in] Pointer to the RECT structure containing the coordinates of the clipping rectangle.

  The only bits that will be painted are the bits that remain inside this rectangle after the scroll operation has been completed.

  If lprcClip is NULL, the entire client area is used.

• hrgnUpdate
  [in] Handle to the region uncovered by the scrolling process.

  ScrollDC defines this region; it is not necessarily a rectangle.

• lprcUpdate
  [out] Long pointer to the RECT structure that receives the coordinates of the rectangle bounding the scrolling update region.

  This is the largest rectangular area that requires repainting.

  When the function returns, the values in the structure are in client coordinates, regardless of the mapping mode for the specified device context.

Return Value

Nonzero indicates success.

Zero indicates failure.

To get extended error information, call GetLastError.

Remarks

If the lprcUpdate parameter is NULL, the system does not compute the update rectangle.

If both the hrgnUpdate and lprcUpdate parameters are NULL, the system does not compute the update region.

If hrgnUpdate is not NULL, the system proceeds as though it contains a valid handle to the region uncovered by the scrolling process (defined by ScrollDC).

When you must scroll the entire client area of a window, use the ScrollWindowEx function.

Requirements

See Also

Reference

RECT
GDI Functions