image_read.hh

// Copyright (C) 2001, 2002, 2003, 2004  EPITA Research and Development Laboratory
//
// This file is part of the Olena Library.  This library is free
// software; you can redistribute it and/or modify it under the terms
// of the GNU General Public License version 2 as published by the
// Free Software Foundation.
//
// This library 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 library; see the file COPYING.  If not, write to
// the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
// MA 02111-1307, USA.
//
// As a special exception, you may use this file as part of a free
// software library without restriction.  Specifically, if other files
// instantiate templates or use macros or inline functions from this
// file, or you compile this file and link it with other files to
// produce an executable, this file does not by itself cause the
// resulting executable to be covered by the GNU General Public
// License.  This exception does not however invalidate any other
// reasons why the executable file might be covered by the GNU General
// Public License.

#ifndef OLENA_IO_IMAGE_READ_HH
# define OLENA_IO_IMAGE_READ_HH

# include <mlc/bool.hh>

# include <oln/config/system.hh>
# include <oln/core/abstract/image_with_dim.hh>
# include <oln/core/image2d.hh>

# include <oln/io/image_base.hh>
# include <oln/io/pnm_read.hh>
# include <oln/io/pnm_read_2d.hh>
# include <oln/io/pnm_read_3d.hh>
# include <oln/io/stream_wrapper.hh>
# include <oln/io/utils.hh>

# include <list>
# include <iostream>

namespace oln {

  namespace io {

    namespace internal {

      template< reader_id R, typename T >
      struct try_readers
      {
        static bool
        by_extension(T& output, std::istream& in, const std::string& ext)
        {
          if (image_reader<R,T>::knows_ext(ext))
            if (image_reader<R,T>::read(in, output))
              return true;
          in.seekg(0, std::ios::beg);
          return try_readers<reader_id(unsigned(R)-1), T>
                   ::by_extension(output, in, ext);
        }

        static bool
        by_data(T& output, std::istream& in)
        {
          if (image_reader<R,T>::read(in, output))
            return true;
          in.seekg(0, std::ios::beg);
          return try_readers<reader_id(unsigned(R)-1), T>::by_data(output, in);
        }
      };

      template< typename T >
      struct try_readers<ReadNone, T>
      {
        static bool
        by_extension(T&, std::istream&, const std::string&)
        {
          return false;
        }

        static bool
        by_data(T&, std::istream&)
        {
          return false;
        }
      };

      struct readers_trier
      {
        template <class T>
        static bool
        doit(T& output, std::istream& in, const std::string ext)
        {
          bool result = try_readers<ReadAny,T>::by_extension(output, in, ext);
          if (!result)
            result = try_readers<ReadAny,T>::by_data(output, in);
          return result;
        }
      };

      template <unsigned N, class E>
      inline bool
      read(abstract::image_with_dim<N,E>& output, const std::string& name)
      {
        mlc::is_true<N == 2 || N == 3>::ensure();

        typedef try_stream_wrappers_in<StreamAny, E, readers_trier>
          stream_trier;

        std::string ext = internal::utils::extension(name);

        if (stream_trier::by_extension(output.exact(), name, ext))
          return true;
        if (stream_trier::by_data(output.exact(), name))
          return true;

        // No valid file found using name directly. Let's try other
        // possible filenames based on name.

        std::list<std::string> names;
        stream_wrappers_find_files<StreamAny>::doit(names, name);

        for (std::list<std::string>::iterator it = names.begin();
             it !=  names.end();
             ++it)
          {
            std::string ext = utils::extension(*it);
            if (stream_trier::by_extension(output.exact(), *it, ext))
              {
                // std::clog << "[" << name << " found as " << *it << "] "
                //           << std::flush;
                return true;
              }
          }
        for (std::list<std::string>::iterator it = names.begin();
             it !=  names.end();
             ++it)
          if (stream_trier::by_data(output.exact(), *it))
            {
              // std::clog << "['" << name << "' found as '" << *it << "'] "
              //        << std::flush;
              return true;
            }
        // std::clog << "[unable to read '" << name << "'] " << std::endl;
        return false;
      }

      template <class E>
      inline bool
      read(abstract::image_with_dim<1, E>& output, const std::string& name)
      {
        image2d<oln_value_type(E)> tmp;
        if (!read(tmp, name))
          return false;
        if (tmp.nrows() != 1)
          return false;
        typename image2d<oln_value_type(E)>::iter_type it(tmp);
        output.exact() = E(tmp.ncols());
        for_all(it)
          output(it.col()) = tmp[it];
        return true;
      }

    } // end of namespace internal

  } // end of namespace io

} // end of namespace oln

#endif // ! OLENA_IO_IMAGE_READ_HH

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