THistDrawable.hxx

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/// \file ROOT/THistDrawable.h
/// \ingroup Hist ROOT7
/// \author Axel Naumann <axel@cern.ch>
/// \date 2015-07-09
/// \warning This is part of the ROOT 7 prototype! It will change without notice. It might trigger earthquakes. Feedback is welcome!

/*************************************************************************
 * Copyright (C) 1995-2015, 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 ROOT7_THistDrawable
#define ROOT7_THistDrawable

#include "ROOT/TDrawable.hxx"
#include "ROOT/THistDrawOptions.hxx"
#include "ROOT/TLogger.hxx"

#include <memory>

class TH1;

namespace ROOT {
namespace Experimental {

template<int DIMENSIONS, class PRECISION,
  template <int D_, class P_, template <class P__> class STORAGE> class... STAT>
class THist;

namespace Detail {
template <int DIMENSIONS> class THistImplPrecisionAgnosticBase;
}

namespace Internal {

void LoadHistPainterLibrary();

template <int DIMENSION>
class THistPainterBase {
  static THistPainterBase<DIMENSION>* fgPainter;

protected:
  THistPainterBase() { fgPainter = this; }
  virtual ~THistPainterBase();

public:
  static THistPainterBase<DIMENSION>* GetPainter() {
    if (!fgPainter)
      LoadHistPainterLibrary();
    return fgPainter;
  }

  /// Paint a THist. All we need is access to its GetBinContent()
  virtual void Paint(TDrawable& obj, THistDrawOptions<DIMENSION> opts,
                     TCanvas& canv) = 0;
};

extern template class THistPainterBase<1>;
extern template class THistPainterBase<2>;
extern template class THistPainterBase<3>;

class THistDrawableBase: public TDrawable {
protected:
  std::unique_ptr<TH1> fOldHist;

public:
  TH1* GetOldHist() const { return fOldHist.get(); }

   THistDrawableBase();
   THistDrawableBase(THistDrawableBase&&);
   virtual ~THistDrawableBase();

   THistDrawableBase& operator=(THistDrawableBase&&);
};

template <int DIMENSIONS>
class THistDrawable final: public THistDrawableBase {
public:
  using HistImpl_t = Detail::THistImplPrecisionAgnosticBase<DIMENSIONS>;

private:
  TUniWeakPtr<HistImpl_t> fHistImpl;
  THistDrawOptions<DIMENSIONS> fOpts;

  bool UpdateOldHist();
public:
   template<class HIST>
   THistDrawable(const std::shared_ptr<HIST>& hist, THistDrawOptions<DIMENSIONS> opts):
      fHistImpl(std::shared_ptr<HistImpl_t>(hist, hist->GetImpl())),
      fOpts(opts) {}

   template<class HIST>
   THistDrawable(std::unique_ptr<HIST>&& hist, THistDrawOptions<DIMENSIONS> opts):
      fHistImpl(std::unique_ptr<HistImpl_t>(std::move(hist->TakeImpl()))),
      fOpts(opts) {}

  /// Paint the histogram
  void Paint(TCanvas& canv) final {
    if (UpdateOldHist())
      THistPainterBase<DIMENSIONS>::GetPainter()->Paint(*this, fOpts, canv);
  }
};

extern template class THistDrawable<1>;
extern template class THistDrawable<2>;
extern template class THistDrawable<3>;

} // namespace Internal
} // namespace Experimental
} // namespace ROOT

#endif