buffhandle.hpp

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/*
  BUFFHANDLE.hpp  -  Buffer handling support for the render engine

  Copyright (C)         Lumiera.org
    2008,               Hermann Vosseler <Ichthyostega@web.de>

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 2 of
  the License, or (at your option) any later version.

  This program 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 General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#ifndef ENGINE_BUFFHANDLE_H
#define ENGINE_BUFFHANDLE_H


#include "lib/error.hpp"
#include "lib/hash-value.h"
#include "steam/streamtype.hpp"


namespace steam {
namespace engine {
  namespace error = lumiera::error;
  
  using lib::HashVal;
  
  class BuffHandle;
  class BufferProvider;
  
  
  
  class BufferDescriptor
    {
    protected:
      BufferProvider* provider_;
      HashVal subClassification_;
      
      BufferDescriptor(BufferProvider& manager, HashVal detail)
        : provider_(&manager)
        , subClassification_(detail)
      { }
      
      friend class BufferProvider;
      friend class BuffHandle;
      
    public:
      // using standard copy operations
      
      bool verifyValidity()  const;
      size_t determineBufferSize() const;
      
      operator HashVal()  const { return subClassification_; }
    };
  
  
  
  
  class BuffHandle
    {
      typedef StreamType::ImplFacade::DataBuffer Buff;
      
      BufferDescriptor descriptor_;
      Buff* pBuffer_; 
      
      
    public:
      typedef Buff* PBuff;
      
      BuffHandle(BufferDescriptor const& typeInfo, void* storage = 0)
        : descriptor_(typeInfo)
        , pBuffer_(static_cast<PBuff>(storage))
        { }
      
      // using standard copy operations
      
      explicit operator bool()  const { return isValid(); }
      
      
      void emit();
      void release();
      
      
      template<typename BU>
      BU& create();
      
      template<typename BU>
      BU& accessAs();
      
      
      Buff&
      operator* ()  const
        {
          ENSURE (pBuffer_);
          return *pBuffer_;
        }
      
      bool
      isValid()  const
        {
          return bool(pBuffer_)
              && descriptor_.verifyValidity();
        }
      
      HashVal
      entryID()  const
        {
          return HashVal(descriptor_);
        }
      
      size_t
      size()  const
        {
          return descriptor_.determineBufferSize();
        }
      
    private:
      template<typename BU>
      void takeOwnershipFor();
      void takeOwnershipFor(BufferDescriptor const& type);
      
      void emergencyCleanup();
    };
  
  
  
  
}} // namespace steam::engine
#endif