boost/gil/position_iterator.hpp

   1 /*
   2     Copyright 2005-2007 Adobe Systems Incorporated
   3
   4     Use, modification and distribution are subject to the Boost Software License,
   5     Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   6     http://www.boost.org/LICENSE_1_0.txt).
   7
   8     See http://opensource.adobe.com/gil for most recent version including documentation.
   9 */
  10
  11 /*************************************************************************************************/
  12
  13 #ifndef GIL_POSITION_ITERATOR_HPP
  14 #define GIL_POSITION_ITERATOR_HPP
  15
  16 ////////////////////////////////////////////////////////////////////////////////////////
  17 /// \file
  18 /// \brief Locator for virtual image views
  19 /// \author Lubomir Bourdev and Hailin Jin \n
  20 ///         Adobe Systems Incorporated
  21 /// \date   2005-2007 \n Last updated on February 12, 2007
  22 ///
  23 ////////////////////////////////////////////////////////////////////////////////////////
  24
  25 #include <boost/iterator/iterator_facade.hpp>
  26 #include "locator.hpp"
  27
  28 namespace boost { namespace gil {
  29
  30 /// \defgroup PixelIteratorModelVirtual position_iterator
  31 /// \ingroup PixelIteratorModel
  32 /// \brief An iterator that remembers its current X,Y position and invokes a function object with it upon dereferencing. Models PixelIteratorConcept, PixelBasedConcept, HasDynamicXStepTypeConcept. Used to create virtual image views.
  33
  34
  35 /// \brief An iterator that remembers its current X,Y position and invokes a function object with it upon dereferencing. Models PixelIteratorConcept. Used to create virtual image views.
  36 ///    Models: StepIteratorConcept, PixelIteratorConcept, PixelBasedConcept, HasDynamicXStepTypeConcept
  37 /// \ingroup PixelIteratorModelVirtual PixelBasedModel
  38 template <typename Deref, // A function object that given a point returns a pixel reference. Models PixelDereferenceAdaptorConcept
  39           int Dim>        // the dimension to advance along
  40 struct position_iterator : public iterator_facade<position_iterator<Deref,Dim>,
  41                                                   typename Deref::value_type,
  42                                                   random_access_traversal_tag,
  43                                                   typename Deref::reference,
  44                                                   typename Deref::argument_type::template axis<Dim>::coord_t> {
  45     typedef iterator_facade<position_iterator<Deref,Dim>,
  46                             typename Deref::value_type,
  47                             random_access_traversal_tag,
  48                             typename Deref::reference,
  49                             typename Deref::argument_type::template axis<Dim>::coord_t> parent_t;
  50     typedef typename parent_t::difference_type difference_type;
  51     typedef typename parent_t::reference       reference;
  52     typedef typename Deref::argument_type      point_t;
  53
  54     position_iterator() {}
  55     position_iterator(const point_t& p, const point_t& step, const Deref& d) : _p(p), _step(step), _d(d) {}
  56
  57     position_iterator(const position_iterator& p) : _p(p._p), _step(p._step), _d(p._d) {}
  58     template <typename D> position_iterator(const position_iterator<D,Dim>& p) : _p(p._p), _step(p._step), _d(p._d) {}
  59     position_iterator& operator=(const position_iterator& p) { _p=p._p; _d=p._d; _step=p._step; return *this; }
  60
  61     const point_t&   pos()      const { return _p; }
  62     const point_t&   step()     const { return _step; }
  63     const Deref&     deref_fn() const { return _d; }
  64
  65     void set_step(difference_type s) { _step[Dim]=s; }
  66     /// For some reason operator[] provided by iterator_adaptor returns a custom class that is convertible to reference
  67     /// We require our own reference because it is registered in iterator_traits
  68     reference operator[](difference_type d) const { point_t p=_p; p[Dim]+=d*_step[Dim]; return _d(p); }
  69
  70 private:
  71     point_t _p, _step;
  72     Deref   _d;
  73
  74     template <typename DE, int DI> friend struct position_iterator;
  75     friend class boost::iterator_core_access;
  76     reference dereference()     const { return _d(_p); }
  77     void increment()                  { _p[Dim]+=_step[Dim]; }
  78     void decrement()                  { _p[Dim]-=_step[Dim]; }
  79     void advance(difference_type d)   { _p[Dim]+=d*_step[Dim]; }
  80
  81     difference_type distance_to(const position_iterator& it) const { return (it._p[Dim]-_p[Dim])/_step[Dim]; }
  82     bool equal(const position_iterator& it) const { return _p==it._p; }
  83 };
  84
  85 template <typename Deref,int Dim>
  86 struct const_iterator_type<position_iterator<Deref,Dim> > {
  87     typedef position_iterator<typename Deref::const_t,Dim> type;
  88 };
  89
  90 template <typename Deref,int Dim>
  91 struct iterator_is_mutable<position_iterator<Deref,Dim> > : public mpl::bool_<Deref::is_mutable> {
  92 };
  93
  94 /////////////////////////////
  95 //  PixelBasedConcept
  96 /////////////////////////////
  97
  98 template <typename Deref,int Dim>
  99 struct color_space_type<position_iterator<Deref,Dim> > : public color_space_type<typename Deref::value_type> {};
 100
 101 template <typename Deref,int Dim>
 102 struct channel_mapping_type<position_iterator<Deref,Dim> > : public channel_mapping_type<typename Deref::value_type> {};
 103
 104 template <typename Deref,int Dim>
 105 struct is_planar<position_iterator<Deref,Dim> > : public mpl::false_ {};
 106
 107 template <typename Deref,int Dim>
 108 struct channel_type<position_iterator<Deref,Dim> > : public channel_type<typename Deref::value_type> {};
 109
 110 /////////////////////////////
 111 //  HasDynamicXStepTypeConcept
 112 /////////////////////////////
 113
 114 template <typename Deref,int Dim>
 115 struct dynamic_x_step_type<position_iterator<Deref,Dim> > {
 116     typedef position_iterator<Deref,Dim> type;
 117 };
 118
 119 } }  // namespace boost::gil
 120
 121 #endif