REFERENCE GUIDE

GetUpdateRectReturn valueCommentsbEraseBOOl Specifies whether the background in the updateregion is to be erased.The return value specifies the status of the update region of the givenwindow. It is nonzero if the update region is not empty. Otherwise, it iszero.The update rectangle retrieved by the BeginPaint function is identical tothat retrieved by the GetUpdateRect function.BeginPaint automatically validates the update region, so any call toGetUpdateRect made immediately after the BeginPaint call retrieves anempty update region.GetUpdateRgnSyntaxParametersReturn valueParametersCommentsint GetUpdateRgn(hWnd, hRgn, fErase)function GetUpdateRgn(Wnd: HWnd; Rgn: HRgn; Erase: Bool): Integer;This function copies a window's update region into a region identified bythe hRgn parameter. The coordinates of this region are relative to theupper-left corner of the window (client coordinates).h WndhRgn[EraseHWND Identifies the window that contains the region to beupdated.HRGN Identifies the update region.BOOl Specifies whether or not the window backgroundshould be erased and non client areas of child windowsshould be drawn. If it is zero, no drawing is done.The return value specifies a short-integer flag that indicates the type ofresulting region. It can be anyone of the following values:COMPLEXREGIONERRORNULLREGIONSIMPLEREGIONThe region has overlapping borders.No region was created.The region is empty.The region has no overlapping borders.BeginPaint automatically validates the update region, so any call toGetUpdateRgn made immediately after the BeginPaint call retrieves anempty update region.358 Software development kit