static extern bool OffsetViewportOrgEx(IntPtr hdc, int nXOffset, int nYOffset, out POINT lpPoint);

Also see GetViewportOrgEx and SetViewportOrgEx.

    static extern bool SetViewportOrgEx(IntPtr hDC, int x, int y, Point[] prevPoint);

SetViewportOrgEx(

static extern bool SetViewportOrgEx(IntPtr hdc, int X, int Y, out POINT lpPoint);

Also see GetViewportOrgEx and OffsetViewportOrgEx.

        EMR_SETVIEWPORTORGEX       = 12,