context.H

/*
 * This file is part of the "Archon" framework.
 * (http://files3d.sourceforge.net)
 *
 * Copyright © 2006 by Kristian Spangsege and Brian Kristiansen.
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation under the terms of the GNU General Public License is
 * hereby granted. No representations are made about the suitability of
 * this software for any purpose. It is provided "as is" without express
 * or implied warranty. See the GNU General Public License
 * (http://www.gnu.org/copyleft/gpl.html) for more details.
 *
 * The characters in this file are ISO8859-1 encoded.
 *
 * The documentation in this file is in "Doxygen" style
 * (http://www.doxygen.org).
 */

#ifndef ARCHON_DISPLAY_CONTEXT_H
#define ARCHON_DISPLAY_CONTEXT_H

#include <stdexcept>
#include <string>

#include <archon/util/exception.H>
#include <archon/util/ref.H>
#include <archon/display/visual.H>
#include <archon/display/drawable.H>

namespace Archon
{
  namespace Display
  {
    using namespace std;
    using namespace Utilities;

    // Fallback declarations. A fallback declaration for class Foo is
    // needed when the header that defines Foo includes this
    // header. In this case this header will not include "foo.H" due
    // to include guards, and Foo would be unknown.
    struct Visual;
    struct Drawable;


    struct ContextAlreadyBoundException: Exception
    {
      ContextAlreadyBoundException(string l): Exception(l) {}
    };

    struct NestedBindingException: Exception
    {
      NestedBindingException(string l): Exception(l) {}
    };


    struct Bind;

    struct Context: virtual RefObjectBase
    {
      virtual Ref<Visual> getVisual() = 0;

      virtual bool isDirect() = 0;

    private:
      friend struct Bind;
      virtual void bind(const Ref<Drawable> &, bool block)
        throw(ContextAlreadyBoundException, NestedBindingException,
              invalid_argument) = 0;
      virtual void unbind() = 0;
    };


    struct Bind
    {
      Bind(const Ref<Context> &c, const Ref<Drawable> &d, bool block = true)
        throw(ContextAlreadyBoundException, NestedBindingException, invalid_argument)
      {
        aquire(c, d, block);
      }

      ~Bind() { release(); }

      void aquire(const Ref<Context> &c, const Ref<Drawable> &d, bool block = true)
        throw(ContextAlreadyBoundException, NestedBindingException, invalid_argument)
      {
        if(context) release();
        c->bind(d, block);
        context = c;
      }

      void release()
      {
        if(!context) return;
        context->unbind();
        context.reset();
      }

    private:
      Ref<Context> context;
    };
  }
}

#endif // ARCHON_DISPLAY_CONTEXT_H

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