/*                       
	This file is part of the CVD Library.

	Copyright (C) 2005 The Authors

	This library is free software; you can redistribute it and/or
	modify it under the terms of the GNU Lesser General Public
	License as published by the Free Software Foundation; either
	version 2.1 of the License, or (at your option) any later version.

	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
	Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public
	License along with this library; if not, write to the Free Software
	Foundation, Inc., 
    51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/
#ifndef CVD_IMAGE_CONVERT_H
#define CVD_IMAGE_CONVERT_H

#include <cvd/config.h>
#include <cvd/internal/convert_pixel_types.h>
#include <cvd/internal/rgb_components.h>
#include <cvd/image.h>

namespace CVD
{

  // The most general case: one row at a time

  template <class From, class To, class Conv=typename Pixel::DefaultConversion<From,To>::type, int both_pod=Internal::is_POD<From>::is_pod && Internal::is_POD<To>::is_pod> struct ConvertImage {
    static void convert(const BasicImage<From>& from, BasicImage<To>& to) {
      for (int r=0; r<from.size().y; r++)
	Pixel::ConvertPixels<From,To,Conv>::convert(from[r], to[r], from.size().x);
    };
  };

  // The blat case: memcpy all data at once 
  template <class T> struct ConvertImage<T,T,Pixel::GenericConversion<T,T>,1> {
    static void convert(const BasicImage<T>& from, BasicImage<T>& to) {
      memcpy(to.data(), from.data(), from.totalsize() * sizeof(T));
    };
  };

  template <> struct ConvertImage<Rgb<byte>, byte, Pixel::CIE<Rgb<byte>, byte>, 1> {
      static void convert(const BasicImage<Rgb<byte> >& from, BasicImage<byte>& to);
  };
  
  template<class Conv, class C, class D> void convert_image(const BasicImage<C>& from, BasicImage<D>& to)
  {
    if (from.size() != to.size())
      throw Exceptions::Image::IncompatibleImageSizes(__FUNCTION__);
    ConvertImage<C,D,Conv>::convert(from, to);
  }
  
  template<template <class From, class To> class Conv, class C, class D> void convert_image(const BasicImage<C>& from, BasicImage<D>& to)
  {
    if (from.size() != to.size())
      throw Exceptions::Image::IncompatibleImageSizes(__FUNCTION__);
    ConvertImage<C,D,Conv<C,D> >::convert(from, to);
  }

  template<class C, class D> void convert_image(const BasicImage<C>& from, BasicImage<D>& to)
  {
      if (from.size() != to.size())
	  throw Exceptions::Image::IncompatibleImageSizes(__FUNCTION__);
      ConvertImage<C,D>::convert(from, to);
  }

  /// Convert an image from one type to another using a specified conversion.
  /// @param D The destination image pixel type
  /// @param C The source image pixel type
  /// @param Conv The conversion to use
  /// @param from The image to convert from
  /// @ingroup gImageIO
  template<class D, class Conv, class C> Image<D> convert_image(const BasicImage<C>& from)
  {
    Image<D> to(from.size());
    convert_image<Conv>(from, to);
    return to;
  }
    
  template<class D, template <class From, class To> class Conv, class C> Image<D> convert_image(const BasicImage<C>& from)
  {
    Image<D> to(from.size());
    convert_image<Conv>(from, to);
    return to;
  }

  /// Convert an image from one type to another using the default.
  /// @param D The destination image pixel type
  /// @param C The source image pixel type
  /// @param from The image to convert from
  /// @ingroup gImageIO
  template<class D, class C> Image<D> convert_image(const BasicImage<C>& from)
  {
    Image<D> to(from.size());
    convert_image(from, to);
    return to;
  }
  
  // Function name changed from 'convert_image' to prevent compile-time
  // error arising from the clash with a function of same name declared above.

  /// Convert an image from one type to another using the default, returning a pair of images.
  /// @param D1 The first destination image pixel type
  /// @param D2 The second destination image pixel type
  /// @param C The source image pixel type
  /// @param from The image to convert from
  /// @ingroup gImageIO
  template<class D1, class D2, class C> std::pair<Image<D1>, Image<D2> > convert_image_pair(const BasicImage<C>& from)
  {
    std::pair<Image<D1>, Image<D2> > to(Image<D1>(from.size()), Image<D2>(from.size()));
    convert_image(from, to.first);
    convert_image(from, to.second);
    return to;
  }  


  #ifndef DOXYGEN_IGNORE_INTERNAL
  namespace Internal
  {
  	template<class C> class ImageConverter{};
	template<class C>  struct ImagePromise<ImageConverter<C> >
	{
		ImagePromise(const BasicImage<C>& im)
		:i(im)
		{}

		const BasicImage<C>& i;
		template<class D> void execute(Image<D>& j)
		{
			j.resize(i.size());
			convert_image(i, j);
		}
	};
  };
  template<class C> Internal::ImagePromise<Internal::ImageConverter<C> > convert_image(const BasicImage<C>& c)
  {
    return Internal::ImagePromise<Internal::ImageConverter<C> >(c);
  }
  #else
  	///Convert an image from one type to another using the default.
	///Type deduction is automatic, and D does not need to be specified. The following usage will work:
	///
	/// \code
	/// Image<byte> a;
	/// Image<byte> b;
	/// ...
	/// b = convert_image(a);
	/// \endcode
	/// Note that this is performed using lazy evaluation, so convertion happens on evaluation of assignment.
    /// @param D The destination image pixel type
    /// @param C The source image pixel type
    /// @param from The image to convert from
	/// @return The converted image
    /// @ingroup gImageIO
  	template<class D> Image<D> convert_image(const BasicImage<C>& from);

  #endif
}

#endif
