CachingDisplayMethod.h

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//# CachingDisplayMethod.h: assistance for auto-caching DisplayData objects
//# Copyright (C) 1999,2000,2001
//# 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
//#
//# $Id$

#ifndef TRIALDISPLAY_CACHINGDISPLAYMETHOD_H
#define TRIALDISPLAY_CACHINGDISPLAYMETHOD_H

#include <casa/aips.h>
#include <display/Display/DisplayEnums.h>
#include <display/DisplayDatas/DisplayMethod.h>

namespace casa { //# NAMESPACE CASA - BEGIN

class AttributeBuffer;
class WorldCanvas;
class WorldCanvasHolder;
class CachingDisplayData;

// <summary> 
// Assistance class for auto-caching of DisplayData objects.
// </summary>

// <use visibility=export>

// <reviewed reviewer="" data="" tests="" demos="">
// </reviewed>

// <prerequisite>
// <li> <linkto class=DisplayMethod> DisplayMethod </linkto>
// <li> <linkto class=CachingDisplayData> CachingDisplayData </linkto>
// </prerequisite>

// <etymology>
// "CachingDisplayMethod" is an implementation of a <linkto
// class=DisplayMethod> DisplayMethod </linkto> which provides a
// single element in a cache of individual depictions of some data.
// </etymology>

// <synopsis>
// </synopsis>


class CachingDisplayMethod : public DisplayMethod {

 public:

  // Constructor.  A single instance of a CachingDisplayMethod is
  // setup to draw on a particular WorldCanvas, and only when
  // particular conditions, as stored in the provided
  // AttributeBuffers, are met.  The parent DisplayData is given
  // in <src>parentDisplayData</src>.
  CachingDisplayMethod(WorldCanvas *worldCanvas, 
                       AttributeBuffer *wchAttributes,
                       AttributeBuffer *ddAttributes,
                       CachingDisplayData *parentDisplayData);

  // Destructor.
  virtual ~CachingDisplayMethod();

  // Return the WorldCanvas recorded in this CachingDisplayMethod.
  virtual WorldCanvas *worldCanvas() 
    { return itsWorldCanvas; }

  // Draw this slice of data on the supplied WorldCanvasHolder.
  virtual void draw(Display::RefreshReason reason, 
                    WorldCanvasHolder &wcHolder);

 protected:

  // (Required) default constructor.
  CachingDisplayMethod();

  // (Required) copy constructor.
  CachingDisplayMethod(const CachingDisplayMethod &other);

  // (Required) copy assignment.
  void operator=(const CachingDisplayMethod &other);

  // Draw into a cached drawing list, called by draw function.
  // The return value is set False if the DM could not draw or
  // does not wish a drawlist to be saved.
  virtual Bool drawIntoList(Display::RefreshReason reason,
                            WorldCanvasHolder &wcHolder) = 0;

 private:

  // Store for the WorldCanvas which this has previously drawn upon.
  WorldCanvas *itsWorldCanvas;

  // Store for WorldCanvasHolder- and DisplayData-specific
  // AttributeBuffers.
  AttributeBuffer *itsWCHAttributes, *itsDDAttributes;

  // Do we have a cached drawing list?
  Bool itsHasList;

  // Store for cached drawing list number.
  uInt itsCachedDrawingList;

};


} //# NAMESPACE CASA - END

#endif