pixel_2d_locator_base Class Template Reference
[Models, Models]
#include <locator.hpp>
List of all members.
Detailed Description
template<typename Loc, typename XIterator, typename YIterator>
 class boost::gil::pixel_2d_locator_base< Loc, XIterator, YIterator >
base class for models of 
PixelLocatorConcept
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: 
     difference_type offset2(2,3);
     locator+=offset2;
     locator[offset2]=my_pixel;
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 pixel_2d_locator_base. A memory-based locator, memory_based_2d_locator and a virtual locator, virtual_2d_locator. The minimum functionality a subclass must provide is this: 
 class my_locator : public pixel_2d_locator_base<my_locator, ..., ...> {  
        typedef ... const_t;                      
        template <typename Deref> struct add_deref {
            typedef ... type;                     
            static type make(const my_locator& loc, const Deref& d);
        };
        my_locator();
        my_locator(const my_locator& pl);
        
        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;
        
        x_iterator&       x();
        y_iterator&       y();
        x_iterator const& x() const;
        y_iterator const& y() const;
        
        y_coord_t         y_distance_to(const my_locator& loc2, x_coord_t xDiff) const;
        
        
        bool              is_1d_traversable(x_coord_t width) const;
 };
Models may choose to override some of the functions in the base class with more efficient versions. 
|  | 
| 
 Public Types | 
| typedef XIterator | x_iterator | 
| typedef YIterator | y_iterator | 
| typedef std::iterator_traits < x_iterator >::value_type
 | value_type | 
| typedef std::iterator_traits < x_iterator >::reference
 | reference | 
| typedef std::iterator_traits < x_iterator >
 ::difference_type
 | coord_t | 
| typedef point2< coord_t > | difference_type | 
| typedef difference_type | point_t | 
| typedef point_t::template axis < 0 >::coord_t
 | x_coord_t | 
| typedef point_t::template axis < 1 >::coord_t
 | y_coord_t | 
| typedef difference_type | cached_location_t | 
| 
 Public Member Functions | 
| bool | operator!= (const Loc &p) const | 
| x_iterator | x_at (x_coord_t dx, y_coord_t dy) const | 
| x_iterator | x_at (const difference_type &d) const | 
| y_iterator | y_at (x_coord_t dx, y_coord_t dy) const | 
| y_iterator | y_at (const difference_type &d) const | 
| Loc | xy_at (x_coord_t dx, y_coord_t dy) const | 
| Loc | xy_at (const difference_type &d) const | 
| template<std::size_t D> | 
| axis< D >::iterator & | axis_iterator () | 
| template<std::size_t D> | 
| axis< D >::iterator const & | axis_iterator () const | 
| template<std::size_t D> | 
| axis< D >::iterator | axis_iterator (const point_t &p) const | 
| reference | operator() (x_coord_t dx, y_coord_t dy) const | 
| reference | operator[] (const difference_type &d) const | 
| reference | operator* () const | 
| Loc & | operator+= (const difference_type &d) | 
| Loc & | operator-= (const difference_type &d) | 
| Loc | operator+ (const difference_type &d) const | 
| Loc | operator- (const difference_type &d) const | 
| cached_location_t | cache_location (const difference_type &d) const | 
| cached_location_t | cache_location (x_coord_t dx, y_coord_t dy) const | 
| 
 Static Public Attributes | 
| static const std::size_t | num_dimensions = 2 | 
| 
 Friends | 
| class | pixel_2d_locator | 
The documentation for this class was generated from the following file: