Source
//# WCRefreshEH.h: WorldCanvas refresh event handler
//# Copyright (C) 1993,1994,1995,1996,1998,1999,2000,2002
//# Associated Universities, Inc. Washington DC, USA.
//#
//# This library is free software; you can redistribute it and/or modify it
//# under the terms of the GNU Library General Public License as published by
//# the Free Software Foundation; either version 2 of the License, or (at your
//# option) any later version.
//#
//# This library is distributed in the hope that it will be useful, but WITHOUT
//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
//# License for more details.
//#
//# You should have received a copy of the GNU Library General Public License
//# along with this library; if not, write to the Free Software Foundation,
//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
//#
//# Correspondence concerning AIPS++ should be addressed as follows:
//# Internet email: aips2-request@nrao.edu.
//# Postal address: AIPS++ Project Office
//# National Radio Astronomy Observatory
//# 520 Edgemont Road
//# Charlottesville, VA 22903-2475 USA
//#
//# $Id$
namespace casa { //# NAMESPACE CASA - BEGIN
//
// <summary>
// Base class for handling WorldCanvas refresh events.
// </summary>
//
// <prerequisite>
// <li> <linkto class="WCRefreshEvent">WCRefreshEvent</linkto>
// <li> Understanding of Display library event-handling methodology
// <li> (Optional) Understanding of the
// <linkto class="PixelCanvas">PixelCanvas</linkto> caching mechanism.
// </prerequisite>
//
// <etymology>
// WCRefreshEH : WorldCanvas refresh event-handler
// </etymology>
//
// <synopsis>
// class designed for derivation to provide a standard way of redrawing the
// screen. To use, derive from this class and implement the () operator. For simple
// applications, the op () should redraw the screen, or rebuild and redraw all display
// lists if display lists were used.
// More advanced applications should maintain display lists and perhaps cache information
// at other levels. These kinds of applications should examine the reason field to see
// what changed so they can minimize the computation needed to redraw the screen.
// The meanings of the reason field are as follows:
//