/****************************************************************************+
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**+
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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).+
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** All rights reserved.+
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** Contact: Nokia Corporation (qt-info@nokia.com)+
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**+
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** This file is part of the examples of the Qt Toolkit.+
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**+
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** $QT_BEGIN_LICENSE:BSD$+
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** You may use this file under the terms of the BSD license as follows:+
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**+
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** "Redistribution and use in source and binary forms, with or without+
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** modification, are permitted provided that the following conditions are+
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** met:+
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**   * Redistributions of source code must retain the above copyright+
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**     notice, this list of conditions and the following disclaimer.+
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**   * Redistributions in binary form must reproduce the above copyright+
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**     notice, this list of conditions and the following disclaimer in+
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**     the documentation and/or other materials provided with the+
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**     distribution.+
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**   * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor+
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**     the names of its contributors may be used to endorse or promote+
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**     products derived from this software without specific prior written+
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**     permission.+
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**+
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** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS+
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** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT+
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** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR+
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** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT+
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** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,+
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** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT+
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** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,+
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** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY+
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** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT+
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** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE+
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** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."+
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** $QT_END_LICENSE$+
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**+
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****************************************************************************/+
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+
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#include "levelmeter.h"+
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+
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#include <math.h>+
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+
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#include <QPainter>+
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#include <QTimer>+
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#include <QDebug>+
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+
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+
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// Constants+
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const int RedrawInterval = 100; // ms+
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const qreal PeakDecayRate = 0.001;+
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const int PeakHoldLevelDuration = 2000; // ms+
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+
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+
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LevelMeter::LevelMeter(QWidget *parent)+
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    :   QWidget(parent)+
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    ,   m_rmsLevel(0.0)+
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    ,   m_peakLevel(0.0)+
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    ,   m_decayedPeakLevel(0.0)+
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    ,   m_peakDecayRate(PeakDecayRate)+
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    ,   m_peakHoldLevel(0.0)+
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    ,   m_redrawTimer(new QTimer(this))+
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    ,   m_rmsColor(Qt::red)+
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    ,   m_peakColor(255, 200, 200, 255)+
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{+
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    setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Preferred);+
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    setMinimumWidth(30);+
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+
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    connect(m_redrawTimer, SIGNAL(timeout()), this, SLOT(redrawTimerExpired()));+
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    m_redrawTimer->start(RedrawInterval);+
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}+
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+
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LevelMeter::~LevelMeter()+
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{+
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+
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}+
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+
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void LevelMeter::reset()+
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{+
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    m_rmsLevel = 0.0;+
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    m_peakLevel = 0.0;+
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    update();+
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}+
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+
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void LevelMeter::levelChanged(qreal rmsLevel, qreal peakLevel, int numSamples)+
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{+
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    // Smooth the RMS signal+
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    const qreal smooth = pow(qreal(0.9), static_cast<qreal>(numSamples) / 256); // TODO: remove this magic number+
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    m_rmsLevel = (m_rmsLevel * smooth) + (rmsLevel * (1.0 - smooth));+
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+
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    if (peakLevel > m_decayedPeakLevel) {+
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        m_peakLevel = peakLevel;+
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        m_decayedPeakLevel = peakLevel;+
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        m_peakLevelChanged.start();+
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    }+
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+
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    if (peakLevel > m_peakHoldLevel) {+
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        m_peakHoldLevel = peakLevel;+
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        m_peakHoldLevelChanged.start();+
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    }+
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+
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    update();+
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}+
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+
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void LevelMeter::redrawTimerExpired()+
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{+
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    // Decay the peak signal+
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    const int elapsedMs = m_peakLevelChanged.elapsed();+
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    const qreal decayAmount = m_peakDecayRate * elapsedMs;+
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    if (decayAmount < m_peakLevel)+
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        m_decayedPeakLevel = m_peakLevel - decayAmount;+
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    else+
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        m_decayedPeakLevel = 0.0;+
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+
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    // Check whether to clear the peak hold level+
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    if (m_peakHoldLevelChanged.elapsed() > PeakHoldLevelDuration)+
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        m_peakHoldLevel = 0.0;+
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+
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    update();+
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}+
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+
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void LevelMeter::paintEvent(QPaintEvent *event)+
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{+
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    Q_UNUSED(event)+
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+
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    QPainter painter(this);+
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    painter.fillRect(rect(), Qt::black);+
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+
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    QRect bar = rect();+
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+
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    bar.setTop(rect().top() + (1.0 - m_peakHoldLevel) * rect().height());+
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    bar.setBottom(bar.top() + 5);+
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    painter.fillRect(bar, m_rmsColor);+
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    bar.setBottom(rect().bottom());+
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+
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    bar.setTop(rect().top() + (1.0 - m_decayedPeakLevel) * rect().height());+
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    painter.fillRect(bar, m_peakColor);+
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+
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    bar.setTop(rect().top() + (1.0 - m_rmsLevel) * rect().height());+
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    painter.fillRect(bar, m_rmsColor);+
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}+
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