1 2 3<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 4 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 5<html xmlns="http://www.w3.org/1999/xhtml"> 6 <head> 7 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 8 9 <title>Point - Boost.GIL documentation</title> 10 <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> 11 <link rel="stylesheet" href="../_static/style.css" type="text/css" /> 12 <script type="text/javascript"> 13 var DOCUMENTATION_OPTIONS = { 14 URL_ROOT: '../', 15 VERSION: '', 16 COLLAPSE_MODINDEX: false, 17 FILE_SUFFIX: '.html' 18 }; 19 </script> 20 <script type="text/javascript" src="../_static/jquery.js"></script> 21 <script type="text/javascript" src="../_static/underscore.js"></script> 22 <script type="text/javascript" src="../_static/doctools.js"></script> 23 <link rel="index" title="Index" href="../genindex.html" /> 24 <link rel="search" title="Search" href="../search.html" /> 25 <link rel="top" title="Boost.GIL documentation" href="../index.html" /> 26 <link rel="up" title="Design Guide" href="index.html" /> 27 <link rel="next" title="Channel" href="channel.html" /> 28 <link rel="prev" title="Concepts" href="concepts.html" /> 29 </head> 30 <body> 31 <div class="header"> 32 <table border="0" cellpadding="7" cellspacing="0" width="100%" summary= 33 "header"> 34 <tr> 35 <td valign="top" width="300"> 36 <h3><a href="../index.html"><img 37 alt="C++ Boost" src="../_static/gil.png" border="0"></a></h3> 38 </td> 39 40 <td > 41 <h1 align="center"><a href="../index.html"></a></h1> 42 </td> 43 <td> 44 <div id="searchbox" style="display: none"> 45 <form class="search" action="../search.html" method="get"> 46 <input type="text" name="q" size="18" /> 47 <input type="submit" value="Search" /> 48 <input type="hidden" name="check_keywords" value="yes" /> 49 <input type="hidden" name="area" value="default" /> 50 </form> 51 </div> 52 <script type="text/javascript">$('#searchbox').show(0);</script> 53 </td> 54 </tr> 55 </table> 56 </div> 57 <hr/> 58 <div class="content"> 59 <div class="navbar" style="text-align:right;"> 60 61 62 <a class="prev" title="Concepts" href="concepts.html"><img src="../_static/prev.png" alt="prev"/></a> 63 <a class="up" title="Design Guide" href="index.html"><img src="../_static/up.png" alt="up"/></a> 64 <a class="next" title="Channel" href="channel.html"><img src="../_static/next.png" alt="next"/></a> 65 66 </div> 67 68 <div class="section" id="point"> 69<h1>Point</h1> 70<div class="contents local topic" id="contents"> 71<ul class="simple"> 72<li><a class="reference internal" href="#overview" id="id1">Overview</a></li> 73<li><a class="reference internal" href="#models" id="id2">Models</a></li> 74</ul> 75</div> 76<div class="section" id="overview"> 77<h2><a class="toc-backref" href="#id1">Overview</a></h2> 78<p>A point defines the location of a pixel inside an image. It can also be used 79to describe the dimensions of an image. In most general terms, points are 80N-dimensional and model the following concept:</p> 81<div class="highlight-cpp"><div class="highlight"><pre><span class="n">concept</span> <span class="n">PointNDConcept</span><span class="o"><</span><span class="k">typename</span> <span class="n">T</span><span class="o">></span> <span class="o">:</span> <span class="n">Regular</span><span class="o"><</span><span class="n">T</span><span class="o">></span> 82<span class="p">{</span> 83 <span class="c1">// the type of a coordinate along each axis</span> 84 <span class="k">template</span> <span class="o"><</span><span class="kt">size_t</span> <span class="n">K</span><span class="o">></span> <span class="k">struct</span> <span class="n">axis</span><span class="p">;</span> <span class="n">where</span> <span class="n">Metafunction</span><span class="o"><</span><span class="n">axis</span><span class="o">></span><span class="p">;</span> 85 86 <span class="k">const</span> <span class="kt">size_t</span> <span class="n">num_dimensions</span><span class="p">;</span> 87 88 <span class="c1">// accessor/modifier of the value of each axis.</span> 89 <span class="k">template</span> <span class="o"><</span><span class="kt">size_t</span> <span class="n">K</span><span class="o">></span> <span class="k">const</span> <span class="k">typename</span> <span class="n">axis</span><span class="o"><</span><span class="n">K</span><span class="o">>::</span><span class="n">type</span><span class="o">&</span> <span class="n">T</span><span class="o">::</span><span class="n">axis_value</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span> 90 <span class="k">template</span> <span class="o"><</span><span class="kt">size_t</span> <span class="n">K</span><span class="o">></span> <span class="k">typename</span> <span class="n">axis</span><span class="o"><</span><span class="n">K</span><span class="o">>::</span><span class="n">type</span><span class="o">&</span> <span class="n">T</span><span class="o">::</span><span class="n">axis_value</span><span class="p">();</span> 91<span class="p">};</span> 92</pre></div> 93</div> 94<p>GIL uses a two-dimensional point, which is a refinement of <code class="docutils literal"><span class="pre">PointNDConcept</span></code> 95in which both dimensions are of the same type:</p> 96<div class="highlight-cpp"><div class="highlight"><pre><span class="n">concept</span> <span class="n">Point2DConcept</span><span class="o"><</span><span class="k">typename</span> <span class="n">T</span><span class="o">></span> <span class="o">:</span> <span class="n">PointNDConcept</span><span class="o"><</span><span class="n">T</span><span class="o">></span> 97<span class="p">{</span> 98 <span class="n">where</span> <span class="n">num_dimensions</span> <span class="o">==</span> <span class="mi">2</span><span class="p">;</span> 99 <span class="n">where</span> <span class="n">SameType</span><span class="o"><</span><span class="n">axis</span><span class="o"><</span><span class="mi">0</span><span class="o">>::</span><span class="n">type</span><span class="p">,</span> <span class="n">axis</span><span class="o"><</span><span class="mi">1</span><span class="o">>::</span><span class="n">type</span><span class="o">></span><span class="p">;</span> 100 101 <span class="k">typename</span> <span class="n">value_type</span> <span class="o">=</span> <span class="n">axis</span><span class="o"><</span><span class="mi">0</span><span class="o">>::</span><span class="n">type</span><span class="p">;</span> 102 103 <span class="k">const</span> <span class="n">value_type</span><span class="o">&</span> <span class="k">operator</span><span class="p">[](</span><span class="k">const</span> <span class="n">T</span><span class="o">&</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">i</span><span class="p">);</span> 104 <span class="n">value_type</span><span class="o">&</span> <span class="k">operator</span><span class="p">[](</span> <span class="n">T</span><span class="o">&</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">i</span><span class="p">);</span> 105 106 <span class="n">value_type</span> <span class="n">x</span><span class="p">,</span><span class="n">y</span><span class="p">;</span> 107<span class="p">};</span> 108</pre></div> 109</div> 110<div class="admonition seealso"> 111<p class="first admonition-title">See also</p> 112<ul class="last simple"> 113<li><a class="reference external" href="reference/structboost_1_1gil_1_1_point_n_d_concept.html">PointNDConcept</a></li> 114<li><a class="reference external" href="reference/structboost_1_1gil_1_1_point2_d_concept.html">Point2DConcept</a></li> 115</ul> 116</div> 117</div> 118<div class="section" id="models"> 119<h2><a class="toc-backref" href="#id2">Models</a></h2> 120<p>GIL provides a model of <code class="docutils literal"><span class="pre">Point2DConcept</span></code>, <code class="docutils literal"><span class="pre">point<T></span></code> where <code class="docutils literal"><span class="pre">T</span></code> is the 121coordinate type.</p> 122</div> 123</div> 124 125 126 <div class="navbar" style="text-align:right;"> 127 128 129 <a class="prev" title="Concepts" href="concepts.html"><img src="../_static/prev.png" alt="prev"/></a> 130 <a class="up" title="Design Guide" href="index.html"><img src="../_static/up.png" alt="up"/></a> 131 <a class="next" title="Channel" href="channel.html"><img src="../_static/next.png" alt="next"/></a> 132 133 </div> 134 </div> 135 <div class="footer" role="contentinfo"> 136 Last updated on 2020-08-11 15:08:48. 137 Created using <a href="http://sphinx-doc.org/">Sphinx</a> 1.5.6. 138 </div> 139 </body> 140</html>
