libs/geometry/doc/html/geometry/reference/core/ring_type.html

   1 <html>
   2 <head>
   3 <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
   4 <title>ring_type</title>
   5 <link rel="stylesheet" href="../../../../../../../doc/src/boostbook.css" type="text/css">
   6 <meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
   7 <link rel="home" href="../../../index.html" title="Chapter&#160;1.&#160;Geometry">
   8 <link rel="up" href="../core.html" title="Core Metafunctions">
   9 <link rel="prev" href="radian.html" title="radian">
  10 <link rel="next" href="tag.html" title="tag">
  11 </head>
  12 <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
  13 <table cellpadding="2" width="100%"><tr>
  14 <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../boost.png"></td>
  15 <td align="center"><a href="../../../../../../../index.html">Home</a></td>
  16 <td align="center"><a href="../../../../../../../libs/libraries.htm">Libraries</a></td>
  17 <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
  18 <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
  19 <td align="center"><a href="../../../../../../../more/index.htm">More</a></td>
  20 </tr></table>
  21 <hr>
  22 <div class="spirit-nav">
  23 <a accesskey="p" href="radian.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../core.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="tag.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a>
  24 </div>
  25 <div class="section">
  26 <div class="titlepage"><div><div><h4 class="title">
  27 <a name="geometry.reference.core.ring_type"></a><a class="link" href="ring_type.html" title="ring_type">ring_type</a>
  28 </h4></div></div></div>
  29 <p>
  30           <a class="indexterm" name="idp109561968"></a>
  31 Metafunction defining <span class="bold"><strong>type</strong></span> as the ring_type
  32           of the specified geometry type.
  33         </p>
  34 <h6>
  35 <a name="geometry.reference.core.ring_type.h0"></a>
  36           <span class="phrase"><a name="geometry.reference.core.ring_type.description"></a></span><a class="link" href="ring_type.html#geometry.reference.core.ring_type.description">Description</a>
  37         </h6>
  38 <p>
  39           A polygon contains one exterior ring and zero or more interior rings (holes).
  40           This metafunction retrieves the type of the rings. Exterior ring and each
  41           of the interior rings all have the same ring_type.
  42         </p>
  43 <h6>
  44 <a name="geometry.reference.core.ring_type.h1"></a>
  45           <span class="phrase"><a name="geometry.reference.core.ring_type.synopsis"></a></span><a class="link" href="ring_type.html#geometry.reference.core.ring_type.synopsis">Synopsis</a>
  46         </h6>
  47 <p>
  48 </p>
  49 <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Geometry</span><span class="special">&gt;</span>
  50 <span class="keyword">struct</span> <span class="identifier">ring_type</span>
  51 <span class="special">{</span>
  52   <span class="comment">// ...</span>
  53 <span class="special">};</span>
  54 </pre>
  55 <p>
  56         </p>
  57 <h6>
  58 <a name="geometry.reference.core.ring_type.h2"></a>
  59           <span class="phrase"><a name="geometry.reference.core.ring_type.template_parameter_s_"></a></span><a class="link" href="ring_type.html#geometry.reference.core.ring_type.template_parameter_s_">Template
  60           parameter(s)</a>
  61         </h6>
  62 <div class="informaltable"><table class="table">
  63 <colgroup>
  64 <col>
  65 <col>
  66 </colgroup>
  67 <thead><tr>
  68 <th>
  69                   <p>
  70                     Parameter
  71                   </p>
  72                 </th>
  73 <th>
  74                   <p>
  75                     Description
  76                   </p>
  77                 </th>
  78 </tr></thead>
  79 <tbody><tr>
  80 <td>
  81                   <p>
  82                     typename Geometry
  83                   </p>
  84                 </td>
  85 <td>
  86                   <p>
  87                     A type fullfilling the Ring, Polygon or MultiPolygon concept.
  88                   </p>
  89                 </td>
  90 </tr></tbody>
  91 </table></div>
  92 <h6>
  93 <a name="geometry.reference.core.ring_type.h3"></a>
  94           <span class="phrase"><a name="geometry.reference.core.ring_type.header"></a></span><a class="link" href="ring_type.html#geometry.reference.core.ring_type.header">Header</a>
  95         </h6>
  96 <p>
  97           Either
  98         </p>
  99 <p>
 100           <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
 101         </p>
 102 <p>
 103           Or
 104         </p>
 105 <p>
 106           <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">core</span><span class="special">/</span><span class="identifier">ring_type</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
 107         </p>
 108 <h6>
 109 <a name="geometry.reference.core.ring_type.h4"></a>
 110           <span class="phrase"><a name="geometry.reference.core.ring_type.complexity"></a></span><a class="link" href="ring_type.html#geometry.reference.core.ring_type.complexity">Complexity</a>
 111         </h6>
 112 <p>
 113           Compile time
 114         </p>
 115 <h6>
 116 <a name="geometry.reference.core.ring_type.h5"></a>
 117           <span class="phrase"><a name="geometry.reference.core.ring_type.example"></a></span><a class="link" href="ring_type.html#geometry.reference.core.ring_type.example">Example</a>
 118         </h6>
 119 <p>
 120           Shows how to use the ring_type metafunction, as well as interior_type
 121         </p>
 122 <p>
 123 </p>
 124 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">iostream</span><span class="special">&gt;</span>
 125 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">typeinfo</span><span class="special">&gt;</span>
 126
 127 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 128 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">polygon</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 129 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">point_xy</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 130
 131 <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
 132 <span class="special">{</span>
 133     <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">d2</span><span class="special">::</span><span class="identifier">point_xy</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;</span> <span class="identifier">point</span><span class="special">;</span>
 134     <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">polygon</span><span class="special">&lt;</span><span class="identifier">point</span><span class="special">&gt;</span> <span class="identifier">polygon</span><span class="special">;</span>
 135
 136     <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">ring_type</span><span class="special">&lt;</span><span class="identifier">polygon</span><span class="special">&gt;::</span><span class="identifier">type</span> <span class="identifier">ring_type</span><span class="special">;</span>
 137     <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">interior_type</span><span class="special">&lt;</span><span class="identifier">polygon</span><span class="special">&gt;::</span><span class="identifier">type</span> <span class="identifier">int_type</span><span class="special">;</span>
 138
 139     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="keyword">typeid</span><span class="special">(</span><span class="identifier">ring_type</span><span class="special">).</span><span class="identifier">name</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
 140     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="keyword">typeid</span><span class="special">(</span><span class="identifier">int_type</span><span class="special">).</span><span class="identifier">name</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
 141
 142     <span class="comment">// So int_type defines a collection of rings,</span>
 143     <span class="comment">// which is a Boost.Range compatible range</span>
 144     <span class="comment">// The type of an element of the collection is the very same ring type again.</span>
 145     <span class="comment">// We show that.</span>
 146     <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_value</span><span class="special">&lt;</span><span class="identifier">int_type</span><span class="special">&gt;::</span><span class="identifier">type</span> <span class="identifier">int_ring_type</span><span class="special">;</span>
 147
 148     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span>
 149         <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">boolalpha</span>
 150         <span class="special">&lt;&lt;</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_same</span><span class="special">&lt;</span><span class="identifier">ring_type</span><span class="special">,</span> <span class="identifier">int_ring_type</span><span class="special">&gt;::</span><span class="identifier">value</span>
 151         <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
 152
 153     <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
 154 <span class="special">}</span>
 155 </pre>
 156 <p>
 157         </p>
 158 <p>
 159           Output (using gcc):
 160         </p>
 161 <pre class="programlisting">N5boost8geometry5model4ringINS1_2d28point_xyIdNS0_2cs9cartesianEEELb1ELb1ESt6vectorSaEE
 162 St6vectorIN5boost8geometry5model4ringINS2_2d28point_xyIdNS1_2cs9cartesianEEELb1ELb1ES_SaEESaIS9_EE
 163 true
 164 </pre>
 165 </div>
 166 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 167 <td align="left"></td>
 168 <td align="right"><div class="copyright-footer">Copyright &#169; 2009-2017 Barend
 169       Gehrels, Bruno Lalande, Mateusz Loskot, Adam Wulkiewicz, Oracle and/or its
 170       affiliates<p>
 171         Distributed under the Boost Software License, Version 1.0. (See accompanying
 172         file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
 173       </p>
 174 </div></td>
 175 </tr></table>
 176 <hr>
 177 <div class="spirit-nav">
 178 <a accesskey="p" href="radian.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../core.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="tag.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a>
 179 </div>
 180 </body>
 181 </html>