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<div class="title">QwtWeedingCurveFitter Class Reference</div> </div>
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<p>A curve fitter implementing Douglas and Peucker algorithm.
<a href="class_qwt_weeding_curve_fitter.html#details">More...</a></p>
<p><code>#include <<a class="el" href="qwt__curve__fitter_8h_source.html">qwt_curve_fitter.h</a>></code></p>
<div class="dynheader">
Inheritance diagram for QwtWeedingCurveFitter:</div>
<div class="dyncontent">
<div class="center"><img src="class_qwt_weeding_curve_fitter__inherit__graph.png" border="0" usemap="#_qwt_weeding_curve_fitter_inherit__map" alt="Inheritance graph"/></div>
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<area shape="rect" id="node2" href="class_qwt_curve_fitter.html" title="Abstract base class for a curve fitter. " alt="" coords="33,5,143,32"/>
</map>
<center><span class="legend">[<a target="top" href="graph_legend.html">legend</a>]</span></center></div>
<table class="memberdecls">
<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="pub-methods"></a>
Public Member Functions</h2></td></tr>
<tr class="memitem:a7deb4d070a329cbdee454023194898a7"><td class="memItemLeft" align="right" valign="top"> </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_weeding_curve_fitter.html#a7deb4d070a329cbdee454023194898a7">QwtWeedingCurveFitter</a> (double <a class="el" href="class_qwt_weeding_curve_fitter.html#a484813f52d921cc5dc57bb6dcf82668d">tolerance</a>=1.0)</td></tr>
<tr class="separator:a7deb4d070a329cbdee454023194898a7"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:abbd30a948fc6974f881678f80a29768c"><td class="memItemLeft" align="right" valign="top"><a id="abbd30a948fc6974f881678f80a29768c"></a>
virtual </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_weeding_curve_fitter.html#abbd30a948fc6974f881678f80a29768c">~QwtWeedingCurveFitter</a> ()</td></tr>
<tr class="memdesc:abbd30a948fc6974f881678f80a29768c"><td class="mdescLeft"> </td><td class="mdescRight">Destructor. <br /></td></tr>
<tr class="separator:abbd30a948fc6974f881678f80a29768c"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:a62c303f6826fef2be7b7bbe82f530680"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_weeding_curve_fitter.html#a62c303f6826fef2be7b7bbe82f530680">setTolerance</a> (double)</td></tr>
<tr class="separator:a62c303f6826fef2be7b7bbe82f530680"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:a484813f52d921cc5dc57bb6dcf82668d"><td class="memItemLeft" align="right" valign="top">double </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_weeding_curve_fitter.html#a484813f52d921cc5dc57bb6dcf82668d">tolerance</a> () const</td></tr>
<tr class="separator:a484813f52d921cc5dc57bb6dcf82668d"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:a9f17a819447cba0e733bd71d90ee2766"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_weeding_curve_fitter.html#a9f17a819447cba0e733bd71d90ee2766">setChunkSize</a> (uint)</td></tr>
<tr class="separator:a9f17a819447cba0e733bd71d90ee2766"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:adfffe6d108f7170bafe5cc81379eaef7"><td class="memItemLeft" align="right" valign="top">uint </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_weeding_curve_fitter.html#adfffe6d108f7170bafe5cc81379eaef7">chunkSize</a> () const</td></tr>
<tr class="separator:adfffe6d108f7170bafe5cc81379eaef7"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:acf876e668d027828c86288e8ac9808ab"><td class="memItemLeft" align="right" valign="top">virtual QPolygonF </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_weeding_curve_fitter.html#acf876e668d027828c86288e8ac9808ab">fitCurve</a> (const QPolygonF &) const</td></tr>
<tr class="separator:acf876e668d027828c86288e8ac9808ab"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="inherit_header pub_methods_class_qwt_curve_fitter"><td colspan="2" onclick="javascript:toggleInherit('pub_methods_class_qwt_curve_fitter')"><img src="closed.png" alt="-"/> Public Member Functions inherited from <a class="el" href="class_qwt_curve_fitter.html">QwtCurveFitter</a></td></tr>
<tr class="memitem:a62919f309f0441d94adea94573d0f778 inherit pub_methods_class_qwt_curve_fitter"><td class="memItemLeft" align="right" valign="top"><a id="a62919f309f0441d94adea94573d0f778"></a>
virtual </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_curve_fitter.html#a62919f309f0441d94adea94573d0f778">~QwtCurveFitter</a> ()</td></tr>
<tr class="memdesc:a62919f309f0441d94adea94573d0f778 inherit pub_methods_class_qwt_curve_fitter"><td class="mdescLeft"> </td><td class="mdescRight">Destructor. <br /></td></tr>
<tr class="separator:a62919f309f0441d94adea94573d0f778 inherit pub_methods_class_qwt_curve_fitter"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="inherited"></a>
Additional Inherited Members</h2></td></tr>
<tr class="inherit_header pro_methods_class_qwt_curve_fitter"><td colspan="2" onclick="javascript:toggleInherit('pro_methods_class_qwt_curve_fitter')"><img src="closed.png" alt="-"/> Protected Member Functions inherited from <a class="el" href="class_qwt_curve_fitter.html">QwtCurveFitter</a></td></tr>
<tr class="memitem:ad804660017ae0f3ede604470724b3df3 inherit pro_methods_class_qwt_curve_fitter"><td class="memItemLeft" align="right" valign="top"><a id="ad804660017ae0f3ede604470724b3df3"></a>
 </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_curve_fitter.html#ad804660017ae0f3ede604470724b3df3">QwtCurveFitter</a> ()</td></tr>
<tr class="memdesc:ad804660017ae0f3ede604470724b3df3 inherit pro_methods_class_qwt_curve_fitter"><td class="mdescLeft"> </td><td class="mdescRight">Constructor. <br /></td></tr>
<tr class="separator:ad804660017ae0f3ede604470724b3df3 inherit pro_methods_class_qwt_curve_fitter"><td class="memSeparator" colspan="2"> </td></tr>
</table>
<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><p>A curve fitter implementing Douglas and Peucker algorithm. </p>
<p>The purpose of the Douglas and Peucker algorithm is that given a 'curve' composed of line segments to find a curve not too dissimilar but that has fewer points. The algorithm defines 'too dissimilar' based on the maximum distance (tolerance) between the original curve and the smoothed curve.</p>
<p>The runtime of the algorithm increases non linear ( worst case O( n*n ) ) and might be very slow for huge polygons. To avoid performance issues it might be useful to split the polygon ( <a class="el" href="class_qwt_weeding_curve_fitter.html#a9f17a819447cba0e733bd71d90ee2766">setChunkSize()</a> ) and to run the algorithm for these smaller parts. The disadvantage of having no interpolation at the borders is for most use cases irrelevant.</p>
<p>The smoothed curve consists of a subset of the points that defined the original curve.</p>
<p>In opposite to <a class="el" href="class_qwt_spline_curve_fitter.html" title="A curve fitter using cubic splines. ">QwtSplineCurveFitter</a> the Douglas and Peucker algorithm reduces the number of points. By adjusting the tolerance parameter according to the axis scales <a class="el" href="class_qwt_spline_curve_fitter.html" title="A curve fitter using cubic splines. ">QwtSplineCurveFitter</a> can be used to implement different level of details to speed up painting of curves of many points. </p>
</div><h2 class="groupheader">Constructor & Destructor Documentation</h2>
<a id="a7deb4d070a329cbdee454023194898a7"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a7deb4d070a329cbdee454023194898a7">◆ </a></span>QwtWeedingCurveFitter()</h2>
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">QwtWeedingCurveFitter::QwtWeedingCurveFitter </td>
<td>(</td>
<td class="paramtype">double </td>
<td class="paramname"><em>tolerance</em> = <code>1.0</code></td><td>)</td>
<td></td>
</tr>
</table>
</div><div class="memdoc">
<p>Constructor</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">tolerance</td><td>Tolerance </td></tr>
</table>
</dd>
</dl>
<dl class="section see"><dt>See also</dt><dd><a class="el" href="class_qwt_weeding_curve_fitter.html#a62c303f6826fef2be7b7bbe82f530680">setTolerance()</a>, <a class="el" href="class_qwt_weeding_curve_fitter.html#a484813f52d921cc5dc57bb6dcf82668d">tolerance()</a> </dd></dl>
</div>
</div>
<h2 class="groupheader">Member Function Documentation</h2>
<a id="adfffe6d108f7170bafe5cc81379eaef7"></a>
<h2 class="memtitle"><span class="permalink"><a href="#adfffe6d108f7170bafe5cc81379eaef7">◆ </a></span>chunkSize()</h2>
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">uint QwtWeedingCurveFitter::chunkSize </td>
<td>(</td>
<td class="paramname"></td><td>)</td>
<td> const</td>
</tr>
</table>
</div><div class="memdoc">
<dl class="section return"><dt>Returns</dt><dd>Maximum for the number of points passed to a run of the algorithm - or 0, when unlimited </dd></dl>
<dl class="section see"><dt>See also</dt><dd><a class="el" href="class_qwt_weeding_curve_fitter.html#a9f17a819447cba0e733bd71d90ee2766">setChunkSize()</a> </dd></dl>
</div>
</div>
<a id="acf876e668d027828c86288e8ac9808ab"></a>
<h2 class="memtitle"><span class="permalink"><a href="#acf876e668d027828c86288e8ac9808ab">◆ </a></span>fitCurve()</h2>
<div class="memitem">
<div class="memproto">
<table class="mlabels">
<tr>
<td class="mlabels-left">
<table class="memname">
<tr>
<td class="memname">QPolygonF QwtWeedingCurveFitter::fitCurve </td>
<td>(</td>
<td class="paramtype">const QPolygonF & </td>
<td class="paramname"><em>points</em></td><td>)</td>
<td> const</td>
</tr>
</table>
</td>
<td class="mlabels-right">
<span class="mlabels"><span class="mlabel">virtual</span></span> </td>
</tr>
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</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">points</td><td>Series of data points </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>Curve points </dd></dl>
<p>Implements <a class="el" href="class_qwt_curve_fitter.html#afa9bf5b328aa553229e204533a60fec0">QwtCurveFitter</a>.</p>
</div>
</div>
<a id="a9f17a819447cba0e733bd71d90ee2766"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a9f17a819447cba0e733bd71d90ee2766">◆ </a></span>setChunkSize()</h2>
<div class="memitem">
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<td class="memname">void QwtWeedingCurveFitter::setChunkSize </td>
<td>(</td>
<td class="paramtype">uint </td>
<td class="paramname"><em>numPoints</em></td><td>)</td>
<td></td>
</tr>
</table>
</div><div class="memdoc">
<p>Limit the number of points passed to a run of the algorithm</p>
<p>The runtime of the Douglas Peucker algorithm increases non linear with the number of points. For a chunk size > 0 the polygon is split into pieces passed to the algorithm one by one.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">numPoints</td><td>Maximum for the number of points passed to the algorithm</td></tr>
</table>
</dd>
</dl>
<dl class="section see"><dt>See also</dt><dd><a class="el" href="class_qwt_weeding_curve_fitter.html#adfffe6d108f7170bafe5cc81379eaef7">chunkSize()</a> </dd></dl>
</div>
</div>
<a id="a62c303f6826fef2be7b7bbe82f530680"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a62c303f6826fef2be7b7bbe82f530680">◆ </a></span>setTolerance()</h2>
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">void QwtWeedingCurveFitter::setTolerance </td>
<td>(</td>
<td class="paramtype">double </td>
<td class="paramname"><em>tolerance</em></td><td>)</td>
<td></td>
</tr>
</table>
</div><div class="memdoc">
<p>Assign the tolerance</p>
<p>The tolerance is the maximum distance, that is acceptable between the original curve and the smoothed curve.</p>
<p>Increasing the tolerance will reduce the number of the resulting points.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">tolerance</td><td>Tolerance</td></tr>
</table>
</dd>
</dl>
<dl class="section see"><dt>See also</dt><dd><a class="el" href="class_qwt_weeding_curve_fitter.html#a484813f52d921cc5dc57bb6dcf82668d">tolerance()</a> </dd></dl>
</div>
</div>
<a id="a484813f52d921cc5dc57bb6dcf82668d"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a484813f52d921cc5dc57bb6dcf82668d">◆ </a></span>tolerance()</h2>
<div class="memitem">
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<td class="memname">double QwtWeedingCurveFitter::tolerance </td>
<td>(</td>
<td class="paramname"></td><td>)</td>
<td> const</td>
</tr>
</table>
</div><div class="memdoc">
<dl class="section return"><dt>Returns</dt><dd>Tolerance </dd></dl>
<dl class="section see"><dt>See also</dt><dd><a class="el" href="class_qwt_weeding_curve_fitter.html#a62c303f6826fef2be7b7bbe82f530680">setTolerance()</a> </dd></dl>
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