class_qwt_plot_raster_item.html

QWT5.01用于Qt开发的二维图形库程序

          <td class="md" valign="top">(&nbsp;</td>
          <td class="md" nowrap valign="top">QPainter *&nbsp;</td>
          <td class="mdname" nowrap> <em>painter</em>, </td>
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          <td class="md" nowrap>const <a class="el" href="class_qwt_scale_map.html">QwtScaleMap</a> &amp;&nbsp;</td>
          <td class="mdname" nowrap> <em>xMap</em>, </td>
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          <td class="md" nowrap>const <a class="el" href="class_qwt_scale_map.html">QwtScaleMap</a> &amp;&nbsp;</td>
          <td class="mdname" nowrap> <em>yMap</em>, </td>
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          <td class="md" nowrap>const QRect &amp;&nbsp;</td>
          <td class="mdname" nowrap> <em>canvasRect</em></td>
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          <td class="md">)&nbsp;</td>
          <td class="md" colspan="2"> const<code> [virtual]</code></td>
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<p>
Draw the raster data. 
<p>
<dl compact><dt><b>Parameters:</b></dt><dd>
  <table border="0" cellspacing="2" cellpadding="0">
    <tr><td valign="top"></td><td valign="top"><em>painter</em>&nbsp;</td><td>Painter </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>xMap</em>&nbsp;</td><td>X-Scale Map </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>yMap</em>&nbsp;</td><td>Y-Scale Map </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>canvasRect</em>&nbsp;</td><td>Contents rect of the plot canvas </td></tr>
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<p>
Implements <a class="el" href="class_qwt_plot_item.html#5483623e4fd1ae85b06b93523784358b">QwtPlotItem</a>.
<p>
Reimplemented in <a class="el" href="class_qwt_plot_spectrogram.html#b76245f919a08375b1f975d507e2afea">QwtPlotSpectrogram</a>.
<p>
Definition at line <a class="el" href="qwt__plot__rasteritem_8cpp-source.html#l00229">229</a> of file <a class="el" href="qwt__plot__rasteritem_8cpp-source.html">qwt_plot_rasteritem.cpp</a>.
<p>
References <a class="el" href="qwt__plot__item_8cpp-source.html#l00367">QwtPlotItem::boundingRect()</a>, <a class="el" href="qwt__plot__item_8cpp-source.html#l00526">QwtPlotItem::invTransform()</a>, <a class="el" href="qwt__plot__item_8cpp-source.html#l00482">QwtPlotItem::paintRect()</a>, and <a class="el" href="qwt__plot__item_8cpp-source.html#l00501">QwtPlotItem::transform()</a>.
<p>
Referenced by <a class="el" href="qwt__plot__spectrogram_8cpp-source.html#l00615">QwtPlotSpectrogram::draw()</a>.    </td>
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<a class="anchor" name="547ce4d8d031b230226cfbd509ef65b5"></a><!-- doxytag: member="QwtPlotRasterItem::invalidateCache" ref="547ce4d8d031b230226cfbd509ef65b5" args="()" --><p>
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          <td class="md" nowrap valign="top">void QwtPlotRasterItem::invalidateCache           </td>
          <td class="md" valign="top">(&nbsp;</td>
          <td class="mdname1" valign="top" nowrap>          </td>
          <td class="md" valign="top">&nbsp;)&nbsp;</td>
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<p>
Invalidate the paint cache <dl compact><dt><b>See also:</b></dt><dd><a class="el" href="class_qwt_plot_raster_item.html#31f74199f7e333c2683b0f18289e4c7f">setCachePolicy</a> </dd></dl>

<p>
Definition at line <a class="el" href="qwt__plot__rasteritem_8cpp-source.html#l00201">201</a> of file <a class="el" href="qwt__plot__rasteritem_8cpp-source.html">qwt_plot_rasteritem.cpp</a>.
<p>
Referenced by <a class="el" href="qwt__plot__rasteritem_8cpp-source.html#l00176">setCachePolicy()</a>, <a class="el" href="qwt__plot__spectrogram_8cpp-source.html#l00202">QwtPlotSpectrogram::setColorMap()</a>, and <a class="el" href="qwt__plot__spectrogram_8cpp-source.html#l00342">QwtPlotSpectrogram::setData()</a>.    </td>
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<a class="anchor" name="610342c1ff21beed110f6454b705368c"></a><!-- doxytag: member="QwtPlotRasterItem::rasterHint" ref="610342c1ff21beed110f6454b705368c" args="(const QwtDoubleRect &amp;) const " --><p>
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          <td class="md" nowrap valign="top">QSize QwtPlotRasterItem::rasterHint           </td>
          <td class="md" valign="top">(&nbsp;</td>
          <td class="md" nowrap valign="top">const QwtDoubleRect &amp;&nbsp;</td>
          <td class="mdname1" valign="top" nowrap>          </td>
          <td class="md" valign="top">&nbsp;)&nbsp;</td>
          <td class="md" nowrap> const<code> [virtual]</code></td>
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<p>
Returns the recommended raster for a given rect. 
<p>
F.e the raster hint can be used to limit the resolution of the image that is rendered.<p>
The default implementation returns an invalid size (QSize()), what means: no hint. 
<p>
Reimplemented in <a class="el" href="class_qwt_plot_spectrogram.html#4e59ddce72db5df3d0be3986e74ab1f7">QwtPlotSpectrogram</a>.
<p>
Definition at line <a class="el" href="qwt__plot__rasteritem_8cpp-source.html#l00217">217</a> of file <a class="el" href="qwt__plot__rasteritem_8cpp-source.html">qwt_plot_rasteritem.cpp</a>.    </td>
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<a class="anchor" name="8767aea6b99f44109e8490e8ee2c3cbe"></a><!-- doxytag: member="QwtPlotRasterItem::renderImage" ref="8767aea6b99f44109e8490e8ee2c3cbe" args="(const QwtScaleMap &amp;xMap, const QwtScaleMap &amp;yMap, const QwtDoubleRect &amp;area) const =0" --><p>
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          <td class="md" nowrap valign="top">virtual QImage QwtPlotRasterItem::renderImage           </td>
          <td class="md" valign="top">(&nbsp;</td>
          <td class="md" nowrap valign="top">const <a class="el" href="class_qwt_scale_map.html">QwtScaleMap</a> &amp;&nbsp;</td>
          <td class="mdname" nowrap> <em>xMap</em>, </td>
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          <td class="md" nowrap align="right"></td>
          <td class="md"></td>
          <td class="md" nowrap>const <a class="el" href="class_qwt_scale_map.html">QwtScaleMap</a> &amp;&nbsp;</td>
          <td class="mdname" nowrap> <em>yMap</em>, </td>
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          <td class="md" nowrap align="right"></td>
          <td class="md"></td>
          <td class="md" nowrap>const QwtDoubleRect &amp;&nbsp;</td>
          <td class="mdname" nowrap> <em>area</em></td>
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          <td class="md"></td>
          <td class="md">)&nbsp;</td>
          <td class="md" colspan="2"> const<code> [protected, pure virtual]</code></td>
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<p>
Renders an image for an area<p>
The format of the image must be QImage::Format_Indexed8, QImage::Format_RGB32 or QImage::Format_ARGB32<p>
<dl compact><dt><b>Parameters:</b></dt><dd>
  <table border="0" cellspacing="2" cellpadding="0">
    <tr><td valign="top"></td><td valign="top"><em>xMap</em>&nbsp;</td><td>Maps x-values into pixel coordinates. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>yMap</em>&nbsp;</td><td>Maps y-values into pixel coordinates. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>area</em>&nbsp;</td><td>Requested area for the image in scale coordinates </td></tr>
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<p>
Implemented in <a class="el" href="class_qwt_plot_spectrogram.html#698a7039b51fa259c39bd93a64743eea">QwtPlotSpectrogram</a>.    </td>
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<a class="anchor" name="14f2ab8ec0994384e6269f869c352273"></a><!-- doxytag: member="QwtPlotRasterItem::setAlpha" ref="14f2ab8ec0994384e6269f869c352273" args="(int alpha)" --><p>
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          <td class="md" nowrap valign="top">void QwtPlotRasterItem::setAlpha           </td>
          <td class="md" valign="top">(&nbsp;</td>
          <td class="md" nowrap valign="top">int&nbsp;</td>
          <td class="mdname1" valign="top" nowrap> <em>alpha</em>          </td>
          <td class="md" valign="top">&nbsp;)&nbsp;</td>
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<p>
Set an alpha value for the raster data. 
<p>
Often a plot has several types of raster data organized in layers. ( f.e a geographical map, with weather statistics ). Using <a class="el" href="class_qwt_plot_raster_item.html#14f2ab8ec0994384e6269f869c352273">setAlpha()</a> raster items can be stacked easily.<p>
The alpha value is a value [0, 255] to control the transparency of the image. 0 represents a fully transparent color, while 255 represents a fully opaque color.<p>
<dl compact><dt><b>Parameters:</b></dt><dd>
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    <tr><td valign="top"></td><td valign="top"><em>alpha</em>&nbsp;</td><td>Alpha value</td></tr>
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<ul>
<li>alpha &gt;= 0<br>
 All alpha values of the pixels returned by <a class="el" href="class_qwt_plot_raster_item.html#8767aea6b99f44109e8490e8ee2c3cbe">renderImage()</a> will be set to alpha, beside those with an alpha value of 0 (invalid pixels).</li><li>alpha &lt; 0 The alpha values returned by <a class="el" href="class_qwt_plot_raster_item.html#8767aea6b99f44109e8490e8ee2c3cbe">renderImage()</a> are not changed.</li></ul>
<p>
The default alpha value is -1.<p>
<dl compact><dt><b>See also:</b></dt><dd><a class="el" href="class_qwt_plot_raster_item.html#96b2faa0bc0fe086bff1abe72bcb2016">alpha()</a> </dd></dl>

<p>
Definition at line <a class="el" href="qwt__plot__rasteritem_8cpp-source.html#l00143">143</a> of file <a class="el" href="qwt__plot__rasteritem_8cpp-source.html">qwt_plot_rasteritem.cpp</a>.
<p>
References <a class="el" href="qwt__plot__item_8cpp-source.html#l00286">QwtPlotItem::itemChanged()</a>.    </td>
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<a class="anchor" name="31f74199f7e333c2683b0f18289e4c7f"></a><!-- doxytag: member="QwtPlotRasterItem::setCachePolicy" ref="31f74199f7e333c2683b0f18289e4c7f" args="(CachePolicy)" --><p>
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          <td class="md" nowrap valign="top">void QwtPlotRasterItem::setCachePolicy           </td>
          <td class="md" valign="top">(&nbsp;</td>
          <td class="md" nowrap valign="top"><a class="el" href="class_qwt_plot_raster_item.html#94929fc4c31c3dab75ee5adcac2d57b0">QwtPlotRasterItem::CachePolicy</a>&nbsp;</td>
          <td class="mdname1" valign="top" nowrap> <em>policy</em>          </td>
          <td class="md" valign="top">&nbsp;)&nbsp;</td>
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<p>
Change the cache policy<p>
The default policy is NoCache<p>
<dl compact><dt><b>Parameters:</b></dt><dd>
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    <tr><td valign="top"></td><td valign="top"><em>policy</em>&nbsp;</td><td>Cache policy </td></tr>
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</dl>
<dl compact><dt><b>See also:</b></dt><dd><a class="el" href="class_qwt_plot_raster_item.html#94929fc4c31c3dab75ee5adcac2d57b0">CachePolicy</a>, <a class="el" href="class_qwt_plot_raster_item.html#c953db5d88084f416b4dbc3ca8a323f3">cachePolicy()</a> </dd></dl>

<p>
Definition at line <a class="el" href="qwt__plot__rasteritem_8cpp-source.html#l00176">176</a> of file <a class="el" href="qwt__plot__rasteritem_8cpp-source.html">qwt_plot_rasteritem.cpp</a>.
<p>
References <a class="el" href="qwt__plot__rasteritem_8cpp-source.html#l00201">invalidateCache()</a>, and <a class="el" href="qwt__plot__item_8cpp-source.html#l00286">QwtPlotItem::itemChanged()</a>.    </td>
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