REFERENCE GUIDE

ScrollDCReturn valueCommentsscrolling update region. This is the largest rectangular areathat requires repainting.This value specifies the outcome of the function. It is nonzero if scrollingis executed. Otherwise, it is zero.If the IprcUpdate parameter is NULL, Windows does not compute theupdate rectangle. If both the hrgnUpdate and IprcUpdate parameters areNULL, Windows does not compute the update region. If hrgnUpdate is notNULL, Windows assumes that it contains a valid region handle to theregion uncovered by the scrolling process (defined by the ScroliDCfunction).An application should use the ScroliWindow function when it is necessaryto scroll the entire client area of a window. Otherwise, it should useScroll DC.ScroliWindowSyntaxParametersvoid ScrollWindow(hWnd, XAmount, YAmount, IpRect, IpClipRect)procedure ScrollWindow(Wnd: HWnd; XAmount, YAmount: Integer;Rect, ClipRect: PRect);This function scrolls a window by moving the contents of the window'sclient area the number of units specified by the XAmount parameter alongthe screen's x-axis and the number of units specified by the Y Amountparameter along the y-axis. The scroll moves right if XAmount is positiveand left if it is negative. The scroll moves down if Y Amount is positive andup if it is negative.h WndXAmountYAmountIpRectIpClipRectHWND Identifies the window whose client area is to bescrolled.int Specifies the amount (in device units) to scroll in the xdirection.int Specifies the amount (in device units) to scroll in the ydirection.LPRECT Points to a RECT data structure that specifies theportion of the client area to be scrolled. If IpRect is NULL, theentire client area is scrolled.LPRECT Points to a RECT data structure that specifies theclipping rectangle to be scrolled. Only bits inside thisChapter 4, Functions directory479