TGLLockable.h

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// @(#)root/gl:$Id$
// Author:  Matevz Tadel, Feb 2007
 
/*************************************************************************
 * Copyright (C) 1995-2004, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
#ifndef ROOT_TGLLockable_H
#define ROOT_TGLLockable_H
 
#include <Rtypes.h>
 
class TGLLockable
{
public:
   enum ELock { kUnlocked,    // Unlocked
                kDrawLock,    // Locked for draw, cannot select or modify
                kSelectLock,  // Locked for select, cannot modify (draw part of select)
                kModifyLock   // Locked for modify, cannot draw or select
              };
 
private:
   TGLLockable(const TGLLockable&) = delete;
   TGLLockable& operator=(const TGLLockable&) = delete;
 
protected:
   // Locking - can take/release via const handle
   mutable ELock     fLock;        // Lock state.
 
   // Ensures unlocking in view of exceptions.
   class TUnlocker
   {
   private:
      TUnlocker(const TUnlocker&) = delete;
      TUnlocker& operator=(const TUnlocker&) = delete;
 
      const TGLLockable *fLockable;
 
   public:
      TUnlocker(const TGLLockable* l) : fLockable(l) {}
      ~TUnlocker()
      {
         if (fLockable->IsLocked())
            fLockable->ReleaseLock(fLockable->CurrentLock());
      }
   };
 
public:
   TGLLockable();
   virtual ~TGLLockable() {}
 
   virtual const char* LockIdStr() const { return "<unknown>"; }
 
   Bool_t TakeLock(ELock lock)    const;
   Bool_t ReleaseLock(ELock lock) const;
   Bool_t IsLocked()    const { return (fLock != kUnlocked); }
   ELock  CurrentLock() const { return fLock; }
 
   Bool_t IsDrawOrSelectLock() const { return fLock == kDrawLock || fLock == kSelectLock; }
 
   static const char * LockName(ELock lock);
   static Bool_t       LockValid(ELock lock);
 
   ClassDef(TGLLockable, 0); // Lock for viewers and scenes.
}; // endclass TGLLockable
 
#endif