Point

.. contents:: :local: :depth: 2

Overview

A point defines the location of a pixel inside an image. It can also be used to describe the dimensions of an image. In most general terms, points are N-dimensional and model the following concept:

.. code-block:: cpp

concept PointNDConcept<typename T> : Regular<T> { // the type of a coordinate along each axis template <size_t K> struct axis; where Metafunction<axis>;

  const size_t num_dimensions;

  // accessor/modifier of the value of each axis.
  template <size_t K> const typename axis<K>::type& T::axis_value() const;
  template <size_t K>       typename axis<K>::type& T::axis_value();

};

GIL uses a two-dimensional point, which is a refinement of PointNDConcept in which both dimensions are of the same type:

.. code-block:: cpp

concept Point2DConcept<typename T> : PointNDConcept<T> { where num_dimensions == 2; where SameType<axis<0>::type, axis<1>::type>;

  typename value_type = axis<0>::type;

  const value_type& operator[](const T&, size_t i);
      value_type& operator[](      T&, size_t i);

  value_type x,y;

};

.. seealso::

• PointNDConcept <reference/structboost_1_1gil_1_1_point_n_d_concept.html>_
• Point2DConcept <reference/structboost_1_1gil_1_1_point2_d_concept.html>_

Models

GIL provides a model of Point2DConcept, point<T> where T is the coordinate type.