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| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="geometry.reference.core.ring_type"></a><a class="link" href="ring_type.html" title="ring_type">ring_type</a> |
| </h4></div></div></div> |
| <p> |
| <a class="indexterm" name="idp122536560"></a> |
| Metafunction defining <span class="bold"><strong>type</strong></span> as the ring_type |
| of the specified geometry type. |
| </p> |
| <h6> |
| <a name="geometry.reference.core.ring_type.h0"></a> |
| <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> |
| </h6> |
| <p> |
| A polygon contains one exterior ring and zero or more interior rings (holes). |
| This metafunction retrieves the type of the rings. Exterior ring and each |
| of the interior rings all have the same ring_type. |
| </p> |
| <h6> |
| <a name="geometry.reference.core.ring_type.h1"></a> |
| <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> |
| </h6> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Geometry</span><span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">ring_type</span> |
| <span class="special">{</span> |
| <span class="comment">// ...</span> |
| <span class="special">};</span> |
| </pre> |
| <p> |
| </p> |
| <h6> |
| <a name="geometry.reference.core.ring_type.h2"></a> |
| <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 |
| parameter(s)</a> |
| </h6> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Parameter |
| </p> |
| </th> |
| <th> |
| <p> |
| Description |
| </p> |
| </th> |
| </tr></thead> |
| <tbody><tr> |
| <td> |
| <p> |
| typename Geometry |
| </p> |
| </td> |
| <td> |
| <p> |
| A type fullfilling the Ring, Polygon or MultiPolygon concept. |
| </p> |
| </td> |
| </tr></tbody> |
| </table></div> |
| <h6> |
| <a name="geometry.reference.core.ring_type.h3"></a> |
| <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> |
| </h6> |
| <p> |
| Either |
| </p> |
| <p> |
| <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special"><</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">></span></code> |
| </p> |
| <p> |
| Or |
| </p> |
| <p> |
| <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special"><</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">></span></code> |
| </p> |
| <h6> |
| <a name="geometry.reference.core.ring_type.h4"></a> |
| <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> |
| </h6> |
| <p> |
| Compile time |
| </p> |
| <h6> |
| <a name="geometry.reference.core.ring_type.h5"></a> |
| <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> |
| </h6> |
| <p> |
| Shows how to use the ring_type metafunction, as well as interior_type |
| </p> |
| <p> |
| </p> |
| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">typeinfo</span><span class="special">></span> |
| |
| <span class="preprocessor">#include</span> <span class="special"><</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">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</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">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</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">></span> |
| |
| <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> |
| <span class="special">{</span> |
| <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"><</span><span class="keyword">double</span><span class="special">></span> <span class="identifier">point</span><span class="special">;</span> |
| <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"><</span><span class="identifier">point</span><span class="special">></span> <span class="identifier">polygon</span><span class="special">;</span> |
| |
| <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"><</span><span class="identifier">polygon</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">ring_type</span><span class="special">;</span> |
| <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"><</span><span class="identifier">polygon</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">int_type</span><span class="special">;</span> |
| |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</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"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</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"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| |
| <span class="comment">// So int_type defines a collection of rings,</span> |
| <span class="comment">// which is a Boost.Range compatible range</span> |
| <span class="comment">// The type of an element of the collection is the very same ring type again.</span> |
| <span class="comment">// We show that.</span> |
| <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_value</span><span class="special"><</span><span class="identifier">int_type</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">int_ring_type</span><span class="special">;</span> |
| |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> |
| <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">boolalpha</span> |
| <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_same</span><span class="special"><</span><span class="identifier">ring_type</span><span class="special">,</span> <span class="identifier">int_ring_type</span><span class="special">>::</span><span class="identifier">value</span> |
| <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| |
| <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> |
| <span class="special">}</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Output (using gcc): |
| </p> |
| <pre class="programlisting">N5boost8geometry5model4ringINS1_2d28point_xyIdNS0_2cs9cartesianEEELb1ELb1ESt6vectorSaEE |
| St6vectorIN5boost8geometry5model4ringINS2_2d28point_xyIdNS1_2cs9cartesianEEELb1ELb1ES_SaEESaIS9_EE |
| true |
| </pre> |
| </div> |
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| <td align="right"><div class="copyright-footer">Copyright © 2009-2015 Barend Gehrels, Bruno Lalande, |
| Mateusz Loskot, Adam Wulkiewicz, Oracle and/or its affiliates<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 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>) |
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