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Breadcrumbs go here --> </ul> </div> <div class="toolbuttons toolblock"> <ul> <li id="smallA" class="t_button">A</li> <li id="medA" class="t_button active">A</li> <li id="bigA" class="t_button">A</li> <li id="print" class="t_button"><a href="javascript:this.print();"> <span>Print</span></a></li> </ul> </div> </div> <div class="content mainContent"> <h1 class="title">levelmeter.cpp Example File</h1> <span class="small-subtitle">demos/spectrum/app/levelmeter.cpp</span> <!-- $$$demos/spectrum/app/levelmeter.cpp-description --> <div class="descr"> <a name="details"></a> <pre class="cpp"> <span class="comment">/**************************************************************************** ** ** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies). ** Contact: http://www.qt-project.org/legal ** ** This file is part of the examples of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:BSD$ ** You may use this file under the terms of the BSD license as follows: ** ** "Redistribution and use in source and binary forms, with or without ** modification, are permitted provided that the following conditions are ** met: ** * Redistributions of source code must retain the above copyright ** notice, this list of conditions and the following disclaimer. ** * Redistributions in binary form must reproduce the above copyright ** notice, this list of conditions and the following disclaimer in ** the documentation and/or other materials provided with the ** distribution. ** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names ** of its contributors may be used to endorse or promote products derived ** from this software without specific prior written permission. ** ** ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." ** ** $QT_END_LICENSE$ ** ****************************************************************************/</span> <span class="preprocessor">#include "levelmeter.h"</span> <span class="preprocessor">#include <math.h></span> <span class="preprocessor">#include <QPainter></span> <span class="preprocessor">#include <QTimer></span> <span class="preprocessor">#include <QDebug></span> <span class="comment">// Constants</span> <span class="keyword">const</span> <span class="type">int</span> RedrawInterval <span class="operator">=</span> <span class="number">100</span>; <span class="comment">// ms</span> <span class="keyword">const</span> <span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> PeakDecayRate <span class="operator">=</span> <span class="number">0.001</span>; <span class="keyword">const</span> <span class="type">int</span> PeakHoldLevelDuration <span class="operator">=</span> <span class="number">2000</span>; <span class="comment">// ms</span> LevelMeter<span class="operator">::</span>LevelMeter(<span class="type"><a href="qwidget.html">QWidget</a></span> <span class="operator">*</span>parent) : <span class="type"><a href="qwidget.html">QWidget</a></span>(parent) <span class="operator">,</span> m_rmsLevel(<span class="number">0.0</span>) <span class="operator">,</span> m_peakLevel(<span class="number">0.0</span>) <span class="operator">,</span> m_decayedPeakLevel(<span class="number">0.0</span>) <span class="operator">,</span> m_peakDecayRate(PeakDecayRate) <span class="operator">,</span> m_peakHoldLevel(<span class="number">0.0</span>) <span class="operator">,</span> m_redrawTimer(<span class="keyword">new</span> <span class="type"><a href="qtimer.html">QTimer</a></span>(<span class="keyword">this</span>)) <span class="operator">,</span> m_rmsColor(<span class="type"><a href="qt.html">Qt</a></span><span class="operator">::</span>red) <span class="operator">,</span> m_peakColor(<span class="number">255</span><span class="operator">,</span> <span class="number">200</span><span class="operator">,</span> <span class="number">200</span><span class="operator">,</span> <span class="number">255</span>) { setSizePolicy(<span class="type"><a href="qsizepolicy.html">QSizePolicy</a></span><span class="operator">::</span>Fixed<span class="operator">,</span> <span class="type"><a href="qsizepolicy.html">QSizePolicy</a></span><span class="operator">::</span>Preferred); setMinimumWidth(<span class="number">30</span>); connect(m_redrawTimer<span class="operator">,</span> SIGNAL(timeout())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(redrawTimerExpired())); m_redrawTimer<span class="operator">-</span><span class="operator">></span>start(RedrawInterval); } LevelMeter<span class="operator">::</span><span class="operator">~</span>LevelMeter() { } <span class="type">void</span> LevelMeter<span class="operator">::</span><a href="qtextstream.html#reset">reset</a>() { m_rmsLevel <span class="operator">=</span> <span class="number">0.0</span>; m_peakLevel <span class="operator">=</span> <span class="number">0.0</span>; update(); } <span class="type">void</span> LevelMeter<span class="operator">::</span>levelChanged(<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> rmsLevel<span class="operator">,</span> <span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> peakLevel<span class="operator">,</span> <span class="type">int</span> numSamples) { <span class="comment">// Smooth the RMS signal</span> <span class="keyword">const</span> <span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> smooth <span class="operator">=</span> pow(<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span>(<span class="number">0.9</span>)<span class="operator">,</span> <span class="keyword">static_cast</span><span class="operator"><</span><span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span><span class="operator">></span>(numSamples) <span class="operator">/</span> <span class="number">256</span>); <span class="comment">// TODO: remove this magic number</span> m_rmsLevel <span class="operator">=</span> (m_rmsLevel <span class="operator">*</span> smooth) <span class="operator">+</span> (rmsLevel <span class="operator">*</span> (<span class="number">1.0</span> <span class="operator">-</span> smooth)); <span class="keyword">if</span> (peakLevel <span class="operator">></span> m_decayedPeakLevel) { m_peakLevel <span class="operator">=</span> peakLevel; m_decayedPeakLevel <span class="operator">=</span> peakLevel; m_peakLevelChanged<span class="operator">.</span>start(); } <span class="keyword">if</span> (peakLevel <span class="operator">></span> m_peakHoldLevel) { m_peakHoldLevel <span class="operator">=</span> peakLevel; m_peakHoldLevelChanged<span class="operator">.</span>start(); } update(); } <span class="type">void</span> LevelMeter<span class="operator">::</span>redrawTimerExpired() { <span class="comment">// Decay the peak signal</span> <span class="keyword">const</span> <span class="type">int</span> elapsedMs <span class="operator">=</span> m_peakLevelChanged<span class="operator">.</span>elapsed(); <span class="keyword">const</span> <span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> decayAmount <span class="operator">=</span> m_peakDecayRate <span class="operator">*</span> elapsedMs; <span class="keyword">if</span> (decayAmount <span class="operator"><</span> m_peakLevel) m_decayedPeakLevel <span class="operator">=</span> m_peakLevel <span class="operator">-</span> decayAmount; <span class="keyword">else</span> m_decayedPeakLevel <span class="operator">=</span> <span class="number">0.0</span>; <span class="comment">// Check whether to clear the peak hold level</span> <span class="keyword">if</span> (m_peakHoldLevelChanged<span class="operator">.</span>elapsed() <span class="operator">></span> PeakHoldLevelDuration) m_peakHoldLevel <span class="operator">=</span> <span class="number">0.0</span>; update(); } <span class="type">void</span> LevelMeter<span class="operator">::</span>paintEvent(<span class="type"><a href="qpaintevent.html">QPaintEvent</a></span> <span class="operator">*</span>event) { Q_UNUSED(event) <span class="type"><a href="qpainter.html">QPainter</a></span> painter(<span class="keyword">this</span>); painter<span class="operator">.</span>fillRect(rect()<span class="operator">,</span> <span class="type"><a href="qt.html">Qt</a></span><span class="operator">::</span>black); <span class="type"><a href="qrect.html">QRect</a></span> bar <span class="operator">=</span> rect(); bar<span class="operator">.</span>setTop(rect()<span class="operator">.</span>top() <span class="operator">+</span> (<span class="number">1.0</span> <span class="operator">-</span> m_peakHoldLevel) <span class="operator">*</span> rect()<span class="operator">.</span>height()); bar<span class="operator">.</span>setBottom(bar<span class="operator">.</span>top() <span class="operator">+</span> <span class="number">5</span>); painter<span class="operator">.</span>fillRect(bar<span class="operator">,</span> m_rmsColor); bar<span class="operator">.</span>setBottom(rect()<span class="operator">.</span>bottom()); bar<span class="operator">.</span>setTop(rect()<span class="operator">.</span>top() <span class="operator">+</span> (<span class="number">1.0</span> <span class="operator">-</span> m_decayedPeakLevel) <span class="operator">*</span> rect()<span class="operator">.</span>height()); painter<span class="operator">.</span>fillRect(bar<span class="operator">,</span> m_peakColor); bar<span class="operator">.</span>setTop(rect()<span class="operator">.</span>top() <span class="operator">+</span> (<span class="number">1.0</span> <span class="operator">-</span> m_rmsLevel) <span class="operator">*</span> rect()<span class="operator">.</span>height()); painter<span class="operator">.</span>fillRect(bar<span class="operator">,</span> m_rmsColor); }</pre> </div> <!-- @@@demos/spectrum/app/levelmeter.cpp --> </div> </div> </div> <div class="ft"> <span></span> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2013 Digia Plc and/or its subsidiaries. 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