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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1"><title>Qwt User's Guide: QwtPlotRasterItem Class Reference</title><link href="doxygen.css" rel="stylesheet" type="text/css"><link href="tabs.css" rel="stylesheet" type="text/css"></head><body><!-- Generated by Doxygen 1.4.6 --><div class="tabs"> <ul> <li><a href="index.html"><span>Main Page</span></a></li> <li id="current"><a href="classes.html"><span>Classes</span></a></li> <li><a href="files.html"><span>Files</span></a></li> <li><a href="pages.html"><span>Related Pages</span></a></li> </ul></div><div class="tabs"> <ul> <li><a href="classes.html"><span>Alphabetical List</span></a></li> <li><a href="annotated.html"><span>Class List</span></a></li> <li><a href="hierarchy.html"><span>Class Hierarchy</span></a></li> <li><a href="functions.html"><span>Class Members</span></a></li> </ul></div><h1>QwtPlotRasterItem Class Reference</h1><!-- doxytag: class="QwtPlotRasterItem" --><!-- doxytag: inherits="QwtPlotItem" -->Inheritance diagram for QwtPlotRasterItem:<p><center><img src="class_qwt_plot_raster_item__inherit__graph.png" border="0" usemap="#_qwt_plot_raster_item__inherit__map" alt="Inheritance graph"></center><map name="_qwt_plot_raster_item__inherit__map"><area href="class_qwt_plot_spectrogram.html" shape="rect" coords="7,157,151,181" alt=""><area href="class_qwt_plot_item.html" shape="rect" coords="32,8,125,32" alt=""></map><center><font size="2">[<a href="graph_legend.html">legend</a>]</font></center>Collaboration diagram for QwtPlotRasterItem:<p><center><img src="class_qwt_plot_raster_item__coll__graph.png" border="0" usemap="#_qwt_plot_raster_item__coll__map" alt="Collaboration graph"></center><map name="_qwt_plot_raster_item__coll__map"><area href="class_qwt_plot_item.html" shape="rect" coords="27,8,120,32" alt=""></map><center><font size="2">[<a href="graph_legend.html">legend</a>]</font></center><a href="class_qwt_plot_raster_item-members.html">List of all members.</a><hr><a name="_details"></a><h2>Detailed Description</h2>A class, which displays raster data. <p>Raster data is a grid of pixel values, that can be represented as a QImage. It is used for many types of information like spectrograms, cartograms, geographical maps ...<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><a class="el" href="class_qwt_plot_raster_item.html">QwtPlotRasterItem</a> is only implemented for images of the following formats: QImage::Format_Indexed8, QImage::Format_ARGB32.<p><dl compact><dt><b>See also:</b></dt><dd><a class="el" href="class_qwt_plot_spectrogram.html">QwtPlotSpectrogram</a> </dd></dl><p><p>Definition at line <a class="el" href="qwt__plot__rasteritem_8h-source.html#l00036">36</a> of file <a class="el" href="qwt__plot__rasteritem_8h-source.html">qwt_plot_rasteritem.h</a>.<table border="0" cellpadding="0" cellspacing="0"><tr><td></td></tr><tr><td colspan="2"><br><h2>Public Types</h2></td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top">enum </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_plot_raster_item.html#94929fc4c31c3dab75ee5adcac2d57b0">CachePolicy</a> { <br> <b>NoCache</b>, <br> <b>PaintCache</b>, <br> <b>ScreenCache</b><br> }</td></tr><tr><td colspan="2"><br><h2>Public Member Functions</h2></td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top"> </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_plot_raster_item.html#2149c1d6b71c607027345a9a51ef3314">QwtPlotRasterItem</a> (const QString &title=QString::null)</td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top"> </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_plot_raster_item.html#f487c6abc8e95200d4537d1373f96be5">QwtPlotRasterItem</a> (const <a class="el" href="class_qwt_text.html">QwtText</a> &title)</td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top">virtual </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_plot_raster_item.html#2715233827c346ab15504dc75d6e9714">~QwtPlotRasterItem</a> ()</td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_plot_raster_item.html#14f2ab8ec0994384e6269f869c352273">setAlpha</a> (int alpha)</td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top">int </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_plot_raster_item.html#96b2faa0bc0fe086bff1abe72bcb2016">alpha</a> () const </td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_plot_raster_item.html#31f74199f7e333c2683b0f18289e4c7f">setCachePolicy</a> (<a class="el" href="class_qwt_plot_raster_item.html#94929fc4c31c3dab75ee5adcac2d57b0">CachePolicy</a>)</td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="el" href="class_qwt_plot_raster_item.html#94929fc4c31c3dab75ee5adcac2d57b0">CachePolicy</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_plot_raster_item.html#c953db5d88084f416b4dbc3ca8a323f3">cachePolicy</a> () const </td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_plot_raster_item.html#547ce4d8d031b230226cfbd509ef65b5">invalidateCache</a> ()</td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top">virtual void </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_plot_raster_item.html#81b062af415a8df33262f23768fd71ad">draw</a> (QPainter *p, const <a class="el" href="class_qwt_scale_map.html">QwtScaleMap</a> &xMap, const <a class="el" href="class_qwt_scale_map.html">QwtScaleMap</a> &yMap, const QRect &rect) const </td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top">virtual QSize </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_plot_raster_item.html#610342c1ff21beed110f6454b705368c">rasterHint</a> (const QwtDoubleRect &) const </td></tr><tr><td colspan="2"><br><h2>Protected Member Functions</h2></td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top">virtual QImage </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_plot_raster_item.html#8767aea6b99f44109e8490e8ee2c3cbe">renderImage</a> (const <a class="el" href="class_qwt_scale_map.html">QwtScaleMap</a> &xMap, const <a class="el" href="class_qwt_scale_map.html">QwtScaleMap</a> &yMap, const QwtDoubleRect &area) const =0</td></tr></table><hr><h2>Member Enumeration Documentation</h2><a class="anchor" name="94929fc4c31c3dab75ee5adcac2d57b0"></a><!-- doxytag: member="QwtPlotRasterItem::CachePolicy" ref="94929fc4c31c3dab75ee5adcac2d57b0" args="" --><p><table class="mdTable" cellpadding="2" cellspacing="0"> <tr> <td class="mdRow"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top">enum <a class="el" href="class_qwt_plot_raster_item.html#94929fc4c31c3dab75ee5adcac2d57b0">QwtPlotRasterItem::CachePolicy</a> </td> </tr> </table> </td> </tr></table><table cellspacing="5" cellpadding="0" border="0"> <tr> <td> </td> <td><p><ul><li>NoCache<br> <a class="el" href="class_qwt_plot_raster_item.html#8767aea6b99f44109e8490e8ee2c3cbe">renderImage()</a> is called, whenever the item has to be repainted</li><li>PaintCache<br> <a class="el" href="class_qwt_plot_raster_item.html#8767aea6b99f44109e8490e8ee2c3cbe">renderImage()</a> is called, whenever the image cache is not valid, or the scales, or the size of the canvas has changed. This type of cache is only useful for improving the performance of hide/show operations. All other situations are already handled by the plot canvas cache.</li><li>ScreenCache<br> The screen cache is an image in size of the screen. As long as the scales don't change the target image is scaled from the cache. This might improve the performance when resizing the plot widget, but suffers from scaling effects.</li></ul><p>The default policy is NoCache <p>Definition at line <a class="el" href="qwt__plot__rasteritem_8h-source.html#l00056">56</a> of file <a class="el" href="qwt__plot__rasteritem_8h-source.html">qwt_plot_rasteritem.h</a>. </td> </tr></table><hr><h2>Constructor & Destructor Documentation</h2><a class="anchor" name="2149c1d6b71c607027345a9a51ef3314"></a><!-- doxytag: member="QwtPlotRasterItem::QwtPlotRasterItem" ref="2149c1d6b71c607027345a9a51ef3314" args="(const QString &title=QString::null)" --><p><table class="mdTable" cellpadding="2" cellspacing="0"> <tr> <td class="mdRow"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top">QwtPlotRasterItem::QwtPlotRasterItem </td> <td class="md" valign="top">( </td> <td class="md" nowrap valign="top">const QString & </td> <td class="mdname1" valign="top" nowrap> <em>title</em> = <code>QString::null</code> </td> <td class="md" valign="top"> ) </td> <td class="md" nowrap><code> [explicit]</code></td> </tr> </table> </td> </tr></table><table cellspacing="5" cellpadding="0" border="0"> <tr> <td> </td> <td><p>Constructor. <p><p>Definition at line <a class="el" href="qwt__plot__rasteritem_8cpp-source.html#l00091">91</a> of file <a class="el" href="qwt__plot__rasteritem_8cpp-source.html">qwt_plot_rasteritem.cpp</a>. </td> </tr></table><a class="anchor" name="f487c6abc8e95200d4537d1373f96be5"></a><!-- doxytag: member="QwtPlotRasterItem::QwtPlotRasterItem" ref="f487c6abc8e95200d4537d1373f96be5" args="(const QwtText &title)" --><p><table class="mdTable" cellpadding="2" cellspacing="0"> <tr> <td class="mdRow"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top">QwtPlotRasterItem::QwtPlotRasterItem </td> <td class="md" valign="top">( </td> <td class="md" nowrap valign="top">const <a class="el" href="class_qwt_text.html">QwtText</a> & </td> <td class="mdname1" valign="top" nowrap> <em>title</em> </td> <td class="md" valign="top"> ) </td> <td class="md" nowrap><code> [explicit]</code></td> </tr> </table> </td> </tr></table><table cellspacing="5" cellpadding="0" border="0"> <tr> <td> </td> <td><p>Constructor. <p><p>Definition at line <a class="el" href="qwt__plot__rasteritem_8cpp-source.html#l00098">98</a> of file <a class="el" href="qwt__plot__rasteritem_8cpp-source.html">qwt_plot_rasteritem.cpp</a>. </td> </tr></table><a class="anchor" name="2715233827c346ab15504dc75d6e9714"></a><!-- doxytag: member="QwtPlotRasterItem::~QwtPlotRasterItem" ref="2715233827c346ab15504dc75d6e9714" args="()" --><p><table class="mdTable" cellpadding="2" cellspacing="0"> <tr> <td class="mdRow"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top">QwtPlotRasterItem::~QwtPlotRasterItem </td> <td class="md" valign="top">( </td> <td class="mdname1" valign="top" nowrap> </td> <td class="md" valign="top"> ) </td> <td class="md" nowrap><code> [virtual]</code></td> </tr> </table> </td> </tr></table><table cellspacing="5" cellpadding="0" border="0"> <tr> <td> </td> <td><p>Destructor. <p><p>Definition at line <a class="el" href="qwt__plot__rasteritem_8cpp-source.html#l00105">105</a> of file <a class="el" href="qwt__plot__rasteritem_8cpp-source.html">qwt_plot_rasteritem.cpp</a>. </td> </tr></table><hr><h2>Member Function Documentation</h2><a class="anchor" name="96b2faa0bc0fe086bff1abe72bcb2016"></a><!-- doxytag: member="QwtPlotRasterItem::alpha" ref="96b2faa0bc0fe086bff1abe72bcb2016" args="() const " --><p><table class="mdTable" cellpadding="2" cellspacing="0"> <tr> <td class="mdRow"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top">int QwtPlotRasterItem::alpha </td> <td class="md" valign="top">( </td> <td class="mdname1" valign="top" nowrap> </td> <td class="md" valign="top"> ) </td> <td class="md" nowrap> const</td> </tr> </table> </td> </tr></table><table cellspacing="5" cellpadding="0" border="0"> <tr> <td> </td> <td><p><dl compact><dt><b>Returns:</b></dt><dd>Alpha value of the raster item </dd></dl><dl compact><dt><b>See also:</b></dt><dd><a class="el" href="class_qwt_plot_raster_item.html#14f2ab8ec0994384e6269f869c352273">setAlpha()</a> </dd></dl><p>Definition at line <a class="el" href="qwt__plot__rasteritem_8cpp-source.html#l00163">163</a> of file <a class="el" href="qwt__plot__rasteritem_8cpp-source.html">qwt_plot_rasteritem.cpp</a>. </td> </tr></table><a class="anchor" name="c953db5d88084f416b4dbc3ca8a323f3"></a><!-- doxytag: member="QwtPlotRasterItem::cachePolicy" ref="c953db5d88084f416b4dbc3ca8a323f3" args="() const " --><p><table class="mdTable" cellpadding="2" cellspacing="0"> <tr> <td class="mdRow"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top"><a class="el" href="class_qwt_plot_raster_item.html#94929fc4c31c3dab75ee5adcac2d57b0">QwtPlotRasterItem::CachePolicy</a> QwtPlotRasterItem::cachePolicy </td> <td class="md" valign="top">( </td> <td class="mdname1" valign="top" nowrap> </td> <td class="md" valign="top"> ) </td> <td class="md" nowrap> const</td> </tr> </table> </td> </tr></table><table cellspacing="5" cellpadding="0" border="0"> <tr> <td> </td> <td><p><dl compact><dt><b>Returns:</b></dt><dd>Cache policy </dd></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#31f74199f7e333c2683b0f18289e4c7f">setCachePolicy()</a> </dd></dl><p>Definition at line <a class="el" href="qwt__plot__rasteritem_8cpp-source.html#l00192">192</a> of file <a class="el" href="qwt__plot__rasteritem_8cpp-source.html">qwt_plot_rasteritem.cpp</a>. </td> </tr></table><a class="anchor" name="81b062af415a8df33262f23768fd71ad"></a><!-- doxytag: member="QwtPlotRasterItem::draw" ref="81b062af415a8df33262f23768fd71ad" args="(QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &rect) const " --><p><table class="mdTable" cellpadding="2" cellspacing="0"> <tr> <td class="mdRow"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top">void QwtPlotRasterItem::draw </td>⌨️ 快捷键说明
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