FrameManager.hpp

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/***********************************
   Copyright 2018 Ravishankar Mathur

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
***********************************/

#ifndef _OF_FRAMEMANAGER_
#define _OF_FRAMEMANAGER_

#include <OpenFrames/Export.h>
#include <OpenFrames/ReferenceFrame.hpp>
#include <OpenThreads/Mutex>
#include <osg/Referenced>
#include <osg/ref_ptr>

namespace OpenFrames
{
  class OF_EXPORT FrameManager : public osg::Referenced
  {
  public:
    FrameManager(ReferenceFrame *frame = NULL) : _frame(frame) {}
  
  enum Priority
  {
    LOW_PRIORITY, // For frequent users, e.g. rendering threads
    HIGH_PRIORITY // For one-off users, e.g. modifying the scene
  };

  void setFrame(ReferenceFrame *frame)
  {
    lock();
    _frame = frame;
    unlock();
  }

    inline ReferenceFrame* getFrame() {return _frame.get();}
    inline osg::Group* getData() 
    {
      if(_frame.valid()) return _frame->getGroup();
      else return NULL;
    }

  inline int lock(Priority priority = HIGH_PRIORITY)
  {
    if(priority == LOW_PRIORITY) _mutexLP.lock();
    _mutexNext.lock();
    int val = _mutexData.lock();
    _mutexNext.unlock();
    return val;
  }
  
  inline int unlock(Priority priority = HIGH_PRIORITY)
  {
    int val = _mutexData.unlock();
    if(priority == LOW_PRIORITY) _mutexLP.unlock();
    return val;
  }
  
  inline int trylock(Priority priority = HIGH_PRIORITY)
  {
    if(priority == LOW_PRIORITY) _mutexLP.lock();
    _mutexNext.lock();
    int val = _mutexData.trylock();
    _mutexNext.unlock();
    return val;
  }
  
  protected:
    virtual ~FrameManager() {}

    osg::ref_ptr<ReferenceFrame> _frame;
    OpenThreads::Mutex _mutexData, _mutexNext, _mutexLP;
  };

}

#endif