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<p>A transformation between coordinate systems.  
 <a href="class_qwt_transform.html#details">More...</a></p>

<p><code>#include &lt;<a class="el" href="qwt__transform_8h_source.html">qwt_transform.h</a>&gt;</code></p>
<div class="dynheader">
Inheritance diagram for QwtTransform:</div>
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<div class="center"><img src="class_qwt_transform__inherit__graph.png" border="0" usemap="#a_qwt_transform_inherit__map" alt="Inheritance graph"/></div>
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<area shape="rect" title="A transformation between coordinate systems." alt="" coords="167,5,271,32"/>
<area shape="rect" href="class_qwt_log_transform.html" title="Logarithmic transformation." alt="" coords="5,80,131,107"/>
<area shape="rect" href="class_qwt_null_transform.html" title="Null transformation." alt="" coords="155,80,282,107"/>
<area shape="rect" href="class_qwt_power_transform.html" title="A transformation using pow()" alt="" coords="306,80,446,107"/>
</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:aa1fa1ab21d0fc01e06d3a6e462008d0b"><td class="memItemLeft" align="right" valign="top"><a id="aa1fa1ab21d0fc01e06d3a6e462008d0b"></a>
&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_transform.html#aa1fa1ab21d0fc01e06d3a6e462008d0b">QwtTransform</a> ()</td></tr>
<tr class="memdesc:aa1fa1ab21d0fc01e06d3a6e462008d0b"><td class="mdescLeft">&#160;</td><td class="mdescRight">Constructor. <br /></td></tr>
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virtual&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_transform.html#aa2653db3104e672464dc569592fc14ab">~QwtTransform</a> ()</td></tr>
<tr class="memdesc:aa2653db3104e672464dc569592fc14ab"><td class="mdescLeft">&#160;</td><td class="mdescRight">Destructor. <br /></td></tr>
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<tr class="memitem:aef97acf17f900905f2a93cec7f61e643"><td class="memItemLeft" align="right" valign="top">virtual double&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_transform.html#aef97acf17f900905f2a93cec7f61e643">bounded</a> (double value) const</td></tr>
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<tr class="memitem:a1093b5856cbc6cf812460535442fb130"><td class="memItemLeft" align="right" valign="top">virtual double&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_transform.html#a1093b5856cbc6cf812460535442fb130">transform</a> (double value) const =0</td></tr>
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<tr class="memitem:a5cfb0a329b8418028baf6974b188d76b"><td class="memItemLeft" align="right" valign="top">virtual double&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_transform.html#a5cfb0a329b8418028baf6974b188d76b">invTransform</a> (double value) const =0</td></tr>
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<tr class="memitem:aae011ee4205fa4391459766d88971809"><td class="memItemLeft" align="right" valign="top"><a id="aae011ee4205fa4391459766d88971809"></a>
virtual <a class="el" href="class_qwt_transform.html">QwtTransform</a> *&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_transform.html#aae011ee4205fa4391459766d88971809">copy</a> () const =0</td></tr>
<tr class="memdesc:aae011ee4205fa4391459766d88971809"><td class="mdescLeft">&#160;</td><td class="mdescRight">Virtualized copy operation. <br /></td></tr>
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<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><p>A transformation between coordinate systems. </p>
<p><a class="el" href="class_qwt_transform.html" title="A transformation between coordinate systems.">QwtTransform</a> manipulates values, when being mapped between the scale and the paint device coordinate system.</p>
<p>A transformation consists of 2 methods:</p>
<ul>
<li>transform</li>
<li>invTransform</li>
</ul>
<p>where one is is the inverse function of the other.</p>
<p>When p1, p2 are the boundaries of the paint device coordinates and s1, s2 the boundaries of the scale, <a class="el" href="class_qwt_scale_map.html" title="A scale map.">QwtScaleMap</a> uses the following calculations:</p>
<ul>
<li>p = p1 + ( p2 - p1 ) * ( T( s ) - T( s1 ) / ( T( s2 ) - T( s1 ) );</li>
<li>s = invT ( T( s1 ) + ( T( s2 ) - T( s1 ) ) * ( p - p1 ) / ( p2 - p1 ) ); </li>
</ul>
</div><h2 class="groupheader">Member Function Documentation</h2>
<a id="aef97acf17f900905f2a93cec7f61e643"></a>
<h2 class="memtitle"><span class="permalink"><a href="#aef97acf17f900905f2a93cec7f61e643">&#9670;&nbsp;</a></span>bounded()</h2>

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          <td class="memname">double QwtTransform::bounded </td>
          <td>(</td>
          <td class="paramtype">double&#160;</td>
          <td class="paramname"><em>value</em></td><td>)</td>
          <td> const</td>
        </tr>
      </table>
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<p>Modify value to be a valid value for the transformation. The default implementation does nothing.</p>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramname">value</td><td>Value to be bounded </td></tr>
  </table>
  </dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>value unmodified </dd></dl>

<p>Reimplemented in <a class="el" href="class_qwt_log_transform.html#a78fa3448e52f738c4907c3dc33874b9e">QwtLogTransform</a>.</p>

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<a id="a5cfb0a329b8418028baf6974b188d76b"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a5cfb0a329b8418028baf6974b188d76b">&#9670;&nbsp;</a></span>invTransform()</h2>

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          <td class="memname">virtual double QwtTransform::invTransform </td>
          <td>(</td>
          <td class="paramtype">double&#160;</td>
          <td class="paramname"><em>value</em></td><td>)</td>
          <td> const</td>
        </tr>
      </table>
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<span class="mlabels"><span class="mlabel">pure virtual</span></span>  </td>
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<p>Inverse transformation function</p>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramname">value</td><td>Value </td></tr>
  </table>
  </dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>Modified value</dd></dl>
<dl class="section see"><dt>See also</dt><dd><a class="el" href="class_qwt_transform.html#a1093b5856cbc6cf812460535442fb130">transform()</a> </dd></dl>

<p>Implemented in <a class="el" href="class_qwt_power_transform.html#a474af795bf5362422e2be64da5e30b8c">QwtPowerTransform</a>, <a class="el" href="class_qwt_log_transform.html#a71a37e9762400eacbadb7d2c75456547">QwtLogTransform</a>, and <a class="el" href="class_qwt_null_transform.html#a33e7bd83a52c275ce5f1d04fa83a2a13">QwtNullTransform</a>.</p>

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<h2 class="memtitle"><span class="permalink"><a href="#a1093b5856cbc6cf812460535442fb130">&#9670;&nbsp;</a></span>transform()</h2>

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          <td class="memname">virtual double QwtTransform::transform </td>
          <td>(</td>
          <td class="paramtype">double&#160;</td>
          <td class="paramname"><em>value</em></td><td>)</td>
          <td> const</td>
        </tr>
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<p>Transformation function</p>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramname">value</td><td>Value </td></tr>
  </table>
  </dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>Modified value</dd></dl>
<dl class="section see"><dt>See also</dt><dd><a class="el" href="class_qwt_transform.html#a5cfb0a329b8418028baf6974b188d76b">invTransform()</a> </dd></dl>

<p>Implemented in <a class="el" href="class_qwt_power_transform.html#aba383b41c251759121ab76e8a10437d0">QwtPowerTransform</a>, <a class="el" href="class_qwt_log_transform.html#ab1a9d0f598911bebfbd7c9e4fac371f5">QwtLogTransform</a>, and <a class="el" href="class_qwt_null_transform.html#af3fd9ac63c157ea3dab991d02d936972">QwtNullTransform</a>.</p>

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