[Boost-bugs] [Boost C++ Libraries] #2222: Make images & views model Collection concept.

Subject: [Boost-bugs] [Boost C++ Libraries] #2222: Make images & views model Collection concept.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-08-19 08:14:07

#2222: Make images & views model Collection concept.
----------------------------------+-----------------------------------------
 Reporter:  john.femiani_at_[hidden]  |        Type:  Feature Requests
   Status:  new                   |   Milestone:  Boost 1.36.0    
Component:  None                  |     Version:  Boost 1.36.0    
 Severity:  Problem               |    Keywords:                  
----------------------------------+-----------------------------------------
 It would be convenient if GIL views modeled
 [http://www.boost.org/doc/libs/1_35_0/libs/utility/Collection.html

 ReversibleCollection] concept.
 In fact they ''almost'' do already.

 Without modeling this concept, it is hard to use an image view with
 boost::range algorithms.



 Suggested patch:
 {{{
 #!patch
 Index: image_view.hpp
 ===================================================================
 --- image_view.hpp      (revision 48190)
 +++ image_view.hpp      (working copy)
 @@ -82,6 +82,9 @@
          typedef typename Loc::template axis<D>::iterator iterator;
 // 1D iterator type along each dimension
      };
      typedef iterator_from_2d<Loc>                    iterator;       //
 1D iterator type for each pixel left-to-right inside top-to-bottom
 +    typedef typename const_t::iterator               const_iterator;
 +    typedef typename const_t::reference              const_reference;
 +    typedef typename std::iterator_traits<iterator>::pointer pointer;
      typedef std::reverse_iterator<iterator>          reverse_iterator;
      typedef std::size_t                              size_type;

 @@ -111,6 +114,47 @@

      template <typename L2> friend void swap(image_view<L2>& x,
 image_view<L2>& y);

 +    ///\brief Exchanges the elements of the current view with those of \a
 other
 +    ///       in constant time.
 +    ///
 +    ///\note Required by concept
 +    ///
 http://www.boost.org/doc/libs/1_35_0/libs/utility/Collection.html

 +    void swap(image_view<Loc>& other)
 +    {
 +        swap(*this, other);
 +    }
 +
 +
 +
 +    ///\brief Returns true if the view has no elements, false otherwise.
 +    ///
 +    ///\note Required by concept
 +    ///
 http://www.boost.org/doc/libs/1_35_0/libs/utility/Collection.html

 +    bool empty() const
 +    {
 +        return width() > 0 && height() > 0;
 +    }
 +
 +    ///\brief Returns a reference to the first element in raster order.
 +    ///
 +    ///\note Required by concept
 +    ///
 http://www.boost.org/doc/libs/1_35_0/libs/utility/Collection.html

 +    ///      since views model ForwardCollection
 +    reference front() const
 +    {
 +        return *begin();
 +    }
 +
 +    ///\brief Returns a reference to the last element in raster order.
 +    ///
 +    ///\note Required by concept
 +    ///
 http://www.boost.org/doc/libs/1_35_0/libs/utility/Collection.html

 +    ///      since views model ReversibleCollection
 +    reference back() const
 +    {
 +        return *rbegin();
 +    }
 +
      const point_t&   dimensions()            const { return _dimensions;
 }
      const locator&   pixels()                const { return _pixels; }
      x_coord_t        width()                 const { return
 dimensions().x; }

 }}}

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/2222>
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