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/*
Copyright 2005-2007 Adobe Systems Incorporated
Use, modification and distribution are subject to the Boost Software License,
Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt).
See http://opensource.adobe.com/gil for most recent version including documentation.
*/
/*************************************************************************************************/
#ifndef GIL_LOCATOR_H
#define GIL_LOCATOR_H
////////////////////////////////////////////////////////////////////////////////////////
/// \file
/// \brief pixel 2D locator
/// \author Lubomir Bourdev and Hailin Jin \n
/// Adobe Systems Incorporated
/// \date 2005-2007 \n September 20, 2006
///
////////////////////////////////////////////////////////////////////////////////////////
#include <cstddef>
#include <cassert>
#include "pixel_iterator.hpp"
////////////////////////////////////////////////////////////////////////////////////////
/// Pixel 2D LOCATOR
////////////////////////////////////////////////////////////////////////////////////////
namespace boost { namespace gil {
//forward declarations
template <typename P> ptrdiff_t memunit_step(const P*);
template <typename P> P* memunit_advanced(const P* p, ptrdiff_t diff);
template <typename P> P& memunit_advanced_ref(P* p, ptrdiff_t diff);
template <typename Iterator, typename D> struct iterator_add_deref;
template <typename T> class point2;
namespace detail {
// helper class specialized for each axis of pixel_2d_locator
template <std::size_t D, typename Loc> class locator_axis;
}
template <typename T> struct dynamic_x_step_type;
template <typename T> struct dynamic_y_step_type;
template <typename T> struct channel_type;
template <typename T> struct color_space_type;
template <typename T> struct channel_mapping_type;
template <typename T> struct is_planar;
template <typename T> struct num_channels;
// The type of a locator or a view that has X and Y swapped. By default it is the same
template <typename T> struct transposed_type {
typedef T type;
};
/// \class pixel_2d_locator_base
/// \brief base class for models of PixelLocatorConcept
/// \ingroup PixelLocatorModel PixelBasedModel
///
/// Pixel locator is similar to a pixel iterator, but allows for 2D navigation of pixels within an image view.
/// It has a 2D difference_type and supports random access operations like:
/// \code
/// difference_type offset2(2,3);
/// locator+=offset2;
/// locator[offset2]=my_pixel;
/// \endcode
///
/// In addition, each coordinate acts as a random-access iterator that can be modified separately:
/// "++locator.x()" or "locator.y()+=10" thereby moving the locator horizontally or vertically.
///
/// It is called a locator because it doesn't implement the complete interface of a random access iterator.
/// For example, increment and decrement operations don't make sense (no way to specify dimension).
/// Also 2D difference between two locators cannot be computed without knowledge of the X position within the image.
///
/// This base class provides most of the methods and typedefs needed to create a model of a locator. GIL provides two
/// locator models as subclasses of \p pixel_2d_locator_base. A memory-based locator, \p memory_based_2d_locator and a virtual
/// locator, \p virtual_2d_locator.
/// The minimum functionality a subclass must provide is this:
/// \code
/// class my_locator : public pixel_2d_locator_base<my_locator, ..., ...> { // supply the types for x-iterator and y-iterator
/// typedef ... const_t; // read-only locator
///
/// template <typename Deref> struct add_deref {
/// typedef ... type; // locator that invokes the Deref dereference object upon pixel access
/// static type make(const my_locator& loc, const Deref& d);
/// };
///
/// my_locator();
/// my_locator(const my_locator& pl);
///
/// // constructors with dynamic step in y (and x). Only valid for locators with dynamic steps
/// my_locator(const my_locator& loc, coord_t y_step);
/// my_locator(const my_locator& loc, coord_t x_step, coord_t y_step, bool transpose);
///
/// bool operator==(const my_locator& p) const;
///
/// // return _references_ to horizontal/vertical iterators. Advancing them moves this locator
/// x_iterator& x();
/// y_iterator& y();
/// x_iterator const& x() const;
/// y_iterator const& y() const;
///
/// // return the vertical distance to another locator. Some models need the horizontal distance to compute it
/// y_coord_t y_distance_to(const my_locator& loc2, x_coord_t xDiff) const;
///
/// // return true iff incrementing an x-iterator located at the last column will position it at the first
/// // column of the next row. Some models need the image width to determine that.
/// bool is_1d_traversable(x_coord_t width) const;
/// };
/// \endcode
///
/// Models may choose to override some of the functions in the base class with more efficient versions.
///
template <typename Loc, typename XIterator, typename YIterator> // The concrete subclass, the X-iterator and the Y-iterator
class pixel_2d_locator_base {
public:
typedef XIterator x_iterator;
typedef YIterator y_iterator;
// typedefs required by ConstRandomAccessNDLocatorConcept
static const std::size_t num_dimensions=2;
typedef typename std::iterator_traits<x_iterator>::value_type value_type;
typedef typename std::iterator_traits<x_iterator>::reference reference; // result of dereferencing
typedef typename std::iterator_traits<x_iterator>::difference_type coord_t; // 1D difference type (same for all dimensions)
typedef point2<coord_t> difference_type; // result of operator-(locator,locator)
typedef difference_type point_t;
template <std::size_t D> struct axis {
typedef typename detail::locator_axis<D,Loc>::coord_t coord_t;
typedef typename detail::locator_axis<D,Loc>::iterator iterator;
};
// typedefs required by ConstRandomAccess2DLocatorConcept
typedef typename point_t::template axis<0>::coord_t x_coord_t;
typedef typename point_t::template axis<1>::coord_t y_coord_t;
bool operator!=(const Loc& p) const { return !(concrete()==p); }
x_iterator x_at(x_coord_t dx, y_coord_t dy) const { Loc tmp=concrete(); tmp+=point_t(dx,dy); return tmp.x(); }
x_iterator x_at(const difference_type& d) const { Loc tmp=concrete(); tmp+=d; return tmp.x(); }
y_iterator y_at(x_coord_t dx, y_coord_t dy) const { Loc tmp=concrete(); tmp+=point_t(dx,dy); return tmp.y(); }
y_iterator y_at(const difference_type& d) const { Loc tmp=concrete(); tmp+=d; return tmp.y(); }
Loc xy_at(x_coord_t dx, y_coord_t dy) const { Loc tmp=concrete(); tmp+=point_t(dx,dy); return tmp; }
Loc xy_at(const difference_type& d) const { Loc tmp=concrete(); tmp+=d; return tmp; }
template <std::size_t D> typename axis<D>::iterator& axis_iterator() { return detail::locator_axis<D,Loc>()(concrete()); }
template <std::size_t D> typename axis<D>::iterator const& axis_iterator() const { return detail::locator_axis<D,Loc>()(concrete()); }
template <std::size_t D> typename axis<D>::iterator axis_iterator(const point_t& p) const { return detail::locator_axis<D,Loc>()(concrete(),p); }
reference operator()(x_coord_t dx, y_coord_t dy) const { return *x_at(dx,dy); }
reference operator[](const difference_type& d) const { return *x_at(d.x,d.y); }
reference operator*() const { return *concrete().x(); }
Loc& operator+=(const difference_type& d) { concrete().x()+=d.x; concrete().y()+=d.y; return concrete(); }
Loc& operator-=(const difference_type& d) { concrete().x()-=d.x; concrete().y()-=d.y; return concrete(); }
Loc operator+(const difference_type& d) const { return xy_at(d); }
Loc operator-(const difference_type& d) const { return xy_at(-d); }
// Some locators can cache 2D coordinates for faster subsequent access. By default there is no caching
typedef difference_type cached_location_t;
cached_location_t cache_location(const difference_type& d) const { return d; }
cached_location_t cache_location(x_coord_t dx, y_coord_t dy)const { return difference_type(dx,dy); }
private:
Loc& concrete() { return (Loc&)*this; }
const Loc& concrete() const { return (const Loc&)*this; }
template <typename X> friend class pixel_2d_locator;
};
// helper classes for each axis of pixel_2d_locator_base
namespace detail {
template <typename Loc>
class locator_axis<0,Loc> {
typedef typename Loc::point_t point_t;
public:
typedef typename point_t::template axis<0>::coord_t coord_t;
typedef typename Loc::x_iterator iterator;
inline iterator& operator()( Loc& loc) const { return loc.x(); }
inline iterator const& operator()(const Loc& loc) const { return loc.x(); }
inline iterator operator()( Loc& loc, const point_t& d) const { return loc.x_at(d); }
inline iterator operator()(const Loc& loc, const point_t& d) const { return loc.x_at(d); }
};
template <typename Loc>
class locator_axis<1,Loc> {
typedef typename Loc::point_t point_t;
public:
typedef typename point_t::template axis<1>::coord_t coord_t;
typedef typename Loc::y_iterator iterator;
inline iterator& operator()( Loc& loc) const { return loc.y(); }
inline iterator const& operator()(const Loc& loc) const { return loc.y(); }
inline iterator operator()( Loc& loc, const point_t& d) const { return loc.y_at(d); }
inline iterator operator()(const Loc& loc, const point_t& d) const { return loc.y_at(d); }
};
}
template <typename Loc, typename XIt, typename YIt>
struct channel_type<pixel_2d_locator_base<Loc,XIt,YIt> > : public channel_type<XIt> {};
template <typename Loc, typename XIt, typename YIt>
struct color_space_type<pixel_2d_locator_base<Loc,XIt,YIt> > : public color_space_type<XIt> {};
template <typename Loc, typename XIt, typename YIt>
struct channel_mapping_type<pixel_2d_locator_base<Loc,XIt,YIt> > : public channel_mapping_type<XIt> {};
template <typename Loc, typename XIt, typename YIt>
struct is_planar<pixel_2d_locator_base<Loc,XIt,YIt> > : public is_planar<XIt> {};
/// \class memory_based_2d_locator
/// \brief Memory-based pixel locator. Models: PixelLocatorConcept,HasDynamicXStepTypeConcept,HasDynamicYStepTypeConcept,HasTransposedTypeConcept
/// \ingroup PixelLocatorModel PixelBasedModel
///
/// The class takes a step iterator as a parameter. The step iterator provides navigation along the vertical axis
/// while its base iterator provides horizontal navigation.
///
/// Each instantiation is optimal in terms of size and efficiency.
/// For example, xy locator over interleaved rgb image results in a step iterator consisting of
/// one std::ptrdiff_t for the row size and one native pointer (8 bytes total). ++locator.x() resolves to pointer
/// increment. At the other extreme, a 2D navigation of the even pixels of a planar CMYK image results in a step
/// iterator consisting of one std::ptrdiff_t for the doubled row size, and one step iterator consisting of
/// one std::ptrdiff_t for the horizontal step of two and a CMYK planar_pixel_iterator consisting of 4 pointers (24 bytes).
/// In this case ++locator.x() results in four native pointer additions.
///
/// Note also that \p memory_based_2d_locator does not require that its element type be a pixel. It could be
/// instantiated with an iterator whose \p value_type models only \p Regular. In this case the locator
/// models the weaker RandomAccess2DLocatorConcept, and does not model PixelBasedConcept.
/// Many generic algorithms don't require the elements to be pixels.
////////////////////////////////////////////////////////////////////////////////////////
template <typename StepIterator>
class memory_based_2d_locator : public pixel_2d_locator_base<memory_based_2d_locator<StepIterator>, typename iterator_adaptor_get_base<StepIterator>::type, StepIterator> {
typedef memory_based_2d_locator<StepIterator> this_t;
GIL_CLASS_REQUIRE(StepIterator, boost::gil, StepIteratorConcept)
public:
typedef pixel_2d_locator_base<memory_based_2d_locator<StepIterator>, typename iterator_adaptor_get_base<StepIterator>::type, StepIterator> parent_t;
typedef memory_based_2d_locator<typename const_iterator_type<StepIterator>::type> const_t; // same as this type, but over const values
typedef typename parent_t::coord_t coord_t;
typedef typename parent_t::x_coord_t x_coord_t;
typedef typename parent_t::y_coord_t y_coord_t;
typedef typename parent_t::x_iterator x_iterator;
typedef typename parent_t::y_iterator y_iterator;
typedef typename parent_t::difference_type difference_type;
typedef typename parent_t::reference reference;
template <typename Deref> struct add_deref {
typedef memory_based_2d_locator<typename iterator_add_deref<StepIterator,Deref>::type> type;
static type make(const memory_based_2d_locator<StepIterator>& loc, const Deref& nderef) {
return type(iterator_add_deref<StepIterator,Deref>::make(loc.y(),nderef));
}
};
memory_based_2d_locator() {}
memory_based_2d_locator(const StepIterator& yit) : _p(yit) {}
template <typename SI> memory_based_2d_locator(const memory_based_2d_locator<SI>& loc, coord_t y_step) : _p(loc.x(), loc.row_size()*y_step) {}
template <typename SI> memory_based_2d_locator(const memory_based_2d_locator<SI>& loc, coord_t x_step, coord_t y_step, bool transpose=false)
: _p(make_step_iterator(loc.x(),(transpose ? loc.row_size() : loc.pixel_size())*x_step),
(transpose ? loc.pixel_size() : loc.row_size())*y_step ) {}
memory_based_2d_locator(x_iterator xit, std::ptrdiff_t row_bytes) : _p(xit,row_bytes) {}
template <typename X> memory_based_2d_locator(const memory_based_2d_locator<X>& pl) : _p(pl._p) {}
memory_based_2d_locator(const memory_based_2d_locator& pl) : _p(pl._p) {}
bool operator==(const this_t& p) const { return _p==p._p; }
x_iterator const& x() const { return _p.base(); }
y_iterator const& y() const { return _p; }
x_iterator& x() { return _p.base(); }
y_iterator& y() { return _p; }
// These are faster versions of functions already provided in the superclass
x_iterator x_at (x_coord_t dx, y_coord_t dy) const { return memunit_advanced(x(), offset(dx,dy)); }
x_iterator x_at (const difference_type& d) const { return memunit_advanced(x(), offset(d.x,d.y)); }
this_t xy_at (x_coord_t dx, y_coord_t dy) const { return this_t(x_at( dx , dy ), row_size()); }
this_t xy_at (const difference_type& d) const { return this_t(x_at( d.x, d.y), row_size()); }
reference operator()(x_coord_t dx, y_coord_t dy) const { return memunit_advanced_ref(x(),offset(dx,dy)); }
reference operator[](const difference_type& d) const { return memunit_advanced_ref(x(),offset(d.x,d.y)); }
this_t& operator+=(const difference_type& d) { memunit_advance(x(),offset(d.x,d.y)); return *this; }
this_t& operator-=(const difference_type& d) { memunit_advance(x(),offset(-d.x,-d.y)); return *this; }
// Memory-based locators can have 1D caching of 2D relative coordinates
typedef std::ptrdiff_t cached_location_t; // type used to store relative location (to allow for more efficient repeated access)
cached_location_t cache_location(const difference_type& d) const { return offset(d.x,d.y); }
cached_location_t cache_location(x_coord_t dx, y_coord_t dy)const { return offset(dx,dy); }
reference operator[](const cached_location_t& loc) const { return memunit_advanced_ref(x(),loc); }
// Only make sense for memory-based locators
std::ptrdiff_t row_size() const { return memunit_step(y()); } // distance in mem units (bytes or bits) between adjacent rows
std::ptrdiff_t pixel_size() const { return memunit_step(x()); } // distance in mem units (bytes or bits) between adjacent pixels on the same row
bool is_1d_traversable(x_coord_t width) const { return row_size()-pixel_size()*width==0; } // is there no gap at the end of each row?
// Returns the vertical distance (it2.y-it1.y) between two x_iterators given the difference of their x positions
std::ptrdiff_t y_distance_to(const this_t& p2, x_coord_t xDiff) const {
std::ptrdiff_t rowDiff=memunit_distance(x(),p2.x())-pixel_size()*xDiff;
assert(( rowDiff % row_size())==0);
return rowDiff / row_size();
}
private:
template <typename X> friend class memory_based_2d_locator;
std::ptrdiff_t offset(x_coord_t x, y_coord_t y) const { return y*row_size() + x*pixel_size(); }
StepIterator _p;
};
/////////////////////////////
// PixelBasedConcept
/////////////////////////////
template <typename SI>
struct color_space_type<memory_based_2d_locator<SI> > : public color_space_type<typename memory_based_2d_locator<SI>::parent_t> {
};
template <typename SI>
struct channel_mapping_type<memory_based_2d_locator<SI> > : public channel_mapping_type<typename memory_based_2d_locator<SI>::parent_t> {
};
template <typename SI>
struct is_planar<memory_based_2d_locator<SI> > : public is_planar<typename memory_based_2d_locator<SI>::parent_t> {
};
template <typename SI>
struct channel_type<memory_based_2d_locator<SI> > : public channel_type<typename memory_based_2d_locator<SI>::parent_t> {
};
/////////////////////////////
// HasDynamicXStepTypeConcept
/////////////////////////////
// Take the base iterator of SI (which is typically a step iterator) and change it to have a step in x
template <typename SI>
struct dynamic_x_step_type<memory_based_2d_locator<SI> > {
private:
typedef typename iterator_adaptor_get_base<SI>::type base_iterator_t;
typedef typename dynamic_x_step_type<base_iterator_t>::type base_iterator_step_t;
typedef typename iterator_adaptor_rebind<SI, base_iterator_step_t>::type dynamic_step_base_t;
public:
typedef memory_based_2d_locator<dynamic_step_base_t> type;
};
/////////////////////////////
// HasDynamicYStepTypeConcept
/////////////////////////////
template <typename SI>
struct dynamic_y_step_type<memory_based_2d_locator<SI> > {
typedef memory_based_2d_locator<SI> type;
};
} } // namespace boost::gil
#endif
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