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| <p><font face="Courier New">/*<br> |
| Copyright 2008 Intel Corporation<br> |
| <br> |
| Use, modification and distribution are subject to the Boost Software License,<br> |
| Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at<br> |
| http://www.boost.org/LICENSE_1_0.txt).<br> |
| */<br> |
| #include <boost/polygon/polygon.hpp><br> |
| #include <cassert><br> |
| namespace gtl = boost::polygon;<br> |
| using namespace boost::polygon::operators;<br><br> |
| //lets make the body of main from point_usage.cpp<br>//a generic function parameterized by point type<br>template <typename Point><br>void test_point() {<br> |
| //constructing a gtl point<br> |
| int x = 10;<br> |
| int y = 20;<br> |
| //Point pt(x, y);<br> |
| Point pt = gtl::construct<Point>(x, y);<br> |
| assert(gtl::x(pt) == 10);<br> |
| assert(gtl::y(pt) == 20);<br> |
| <br> |
| //a quick primer in isotropic point access<br> |
| typedef gtl::orientation_2d O;<br> |
| using gtl::HORIZONTAL;<br> |
| using gtl::VERTICAL;<br> |
| O o = HORIZONTAL;<br> |
| assert(gtl::x(pt) == gtl::get(pt, o));<br> |
| <br> |
| o = o.get_perpendicular();<br> |
| assert(o == VERTICAL);<br> |
| assert(gtl::y(pt) == gtl::get(pt, o));<br> |
| <br> |
| gtl::set(pt, o, 30);<br> |
| assert(gtl::y(pt) == 30);<br> |
| <br> |
| //using some of the library functions<br> |
| //Point pt2(10, 30);<br> |
| Point pt2 = gtl::construct<Point>(10, 30);<br> |
| assert(gtl::equivalence(pt, pt2));<br> |
| <br> |
| gtl::transformation<int> tr(gtl::axis_transformation::SWAP_XY);<br> |
| gtl::transform(pt, tr);<br> |
| assert(gtl::equivalence(pt, gtl::construct<Point>(30, 10)));<br> |
| <br> |
| gtl::transformation<int> tr2 = tr.inverse();<br> |
| assert(tr == tr2); //SWAP_XY is its own inverse transform<br> |
| <br> |
| gtl::transform(pt, tr2);<br> |
| assert(gtl::equivalence(pt, pt2)); //the two points are equal again<br> |
| <br> |
| gtl::move(pt, o, 10); //move pt 10 units in y<br> |
| assert(gtl::euclidean_distance(pt, pt2) == 10.0f);<br> |
| <br> |
| gtl::move(pt, o.get_perpendicular(), 10); //move pt 10 units in x<br> |
| assert(gtl::manhattan_distance(pt, pt2) == 20);<br>}<br> |
| <br>//Now lets declare our own point type<br>//Bjarne says that if a class doesn't maintain an<br>//invariant just use a struct.<br>struct CPoint {<br> |
| int x;<br> |
| int y;<br>};<br> |
| <br>//There, nice a simple...but wait, it doesn't do anything<br>//how do we use it to do all the things a point needs to do?<br> |
| <br> |
| <br>//First we register it as a point with boost polygon<br>namespace boost { |
| namespace polygon {<br> |
| template <><br> |
| struct geometry_concept<CPoint> { typedef point_concept type; };<br> <br> |
| <br> //Then we specialize the gtl point traits for our point type<br> |
| template <><br> |
| struct point_traits<CPoint> {<br> |
| |
| typedef int coordinate_type;<br> |
| <br> |
| |
| static inline coordinate_type get(const CPoint& point, <br> |
| |
| orientation_2d orient) {<br> |
| |
| |
| if(orient == HORIZONTAL)<br> |
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| |
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| return point.x;<br> |
| |
| |
| return point.y;<br> |
| |
| }<br> |
| };<br> |
| <br> |
| template <><br> |
| struct point_mutable_traits<CPoint> {<br> |
| |
| static inline void set(CPoint& point, orientation_2d orient, int value) {<br> |
| |
| |
| if(orient == HORIZONTAL)<br> |
| |
| |
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| point.x = value;<br> |
| |
| |
| else<br> |
| |
| |
| point.y = value;<br> |
| |
| }<br> |
| |
| static inline CPoint construct(int x_value, int y_value) {<br> |
| |
| |
| CPoint retval;<br> |
| |
| |
| retval.x = x_value;<br> |
| |
| |
| retval.y = y_value; <br> |
| |
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| return retval;<br> |
| |
| }<br> |
| };<br>} }<br> |
| <br>//Now lets see if the CPoint works with the library functions<br>int main() {<br> |
| test_point<CPoint>(); //yay! All your testing is done for you.<br> |
| return 0;<br>}<br> |
| <br>//Now you know how to map a user type to the library point concept<br>//and how to write a generic function parameterized by point type<br>//using the library interfaces to access it.<br> |
| </font></p> |
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| <table class="docinfo" rules="none" frame="void" id="table1"> |
| <colgroup> |
| <col class="docinfo-name"><col class="docinfo-content"> |
| </colgroup> |
| <tbody vAlign="top"> |
| <tr> |
| <th class="docinfo-name">Copyright:</th> |
| <td>Copyright © Intel Corporation 2008-2010.</td> |
| </tr> |
| <tr class="field"> |
| <th class="docinfo-name">License:</th> |
| <td class="field-body">Distributed under the Boost Software License, |
| Version 1.0. (See accompanying file <tt class="literal"> |
| <span class="pre">LICENSE_1_0.txt</span></tt> or copy at |
| <a class="reference" target="_top" href="http://www.boost.org/LICENSE_1_0.txt"> |
| http://www.boost.org/LICENSE_1_0.txt</a>)</td> |
| </tr> |
| </table> |
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| </body> |
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