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Diffstat (limited to 'examples/multimedia/spectrum/app/levelmeter.cpp')
-rw-r--r-- | examples/multimedia/spectrum/app/levelmeter.cpp | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/examples/multimedia/spectrum/app/levelmeter.cpp b/examples/multimedia/spectrum/app/levelmeter.cpp new file mode 100644 index 000000000..2fde9184a --- /dev/null +++ b/examples/multimedia/spectrum/app/levelmeter.cpp @@ -0,0 +1,142 @@ +/**************************************************************************** +** +** Copyright (C) 2012 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." +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include "levelmeter.h" + +#include <math.h> + +#include <QPainter> +#include <QTimer> +#include <QDebug> + + +// Constants +const int RedrawInterval = 100; // ms +const qreal PeakDecayRate = 0.001; +const int PeakHoldLevelDuration = 2000; // ms + + +LevelMeter::LevelMeter(QWidget *parent) + : QWidget(parent) + , m_rmsLevel(0.0) + , m_peakLevel(0.0) + , m_decayedPeakLevel(0.0) + , m_peakDecayRate(PeakDecayRate) + , m_peakHoldLevel(0.0) + , m_redrawTimer(new QTimer(this)) + , m_rmsColor(Qt::red) + , m_peakColor(255, 200, 200, 255) +{ + setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Preferred); + setMinimumWidth(30); + + connect(m_redrawTimer, SIGNAL(timeout()), this, SLOT(redrawTimerExpired())); + m_redrawTimer->start(RedrawInterval); +} + +LevelMeter::~LevelMeter() +{ + +} + +void LevelMeter::reset() +{ + m_rmsLevel = 0.0; + m_peakLevel = 0.0; + update(); +} + +void LevelMeter::levelChanged(qreal rmsLevel, qreal peakLevel, int numSamples) +{ + // Smooth the RMS signal + const qreal smooth = pow(qreal(0.9), static_cast<qreal>(numSamples) / 256); // TODO: remove this magic number + m_rmsLevel = (m_rmsLevel * smooth) + (rmsLevel * (1.0 - smooth)); + + if (peakLevel > m_decayedPeakLevel) { + m_peakLevel = peakLevel; + m_decayedPeakLevel = peakLevel; + m_peakLevelChanged.start(); + } + + if (peakLevel > m_peakHoldLevel) { + m_peakHoldLevel = peakLevel; + m_peakHoldLevelChanged.start(); + } + + update(); +} + +void LevelMeter::redrawTimerExpired() +{ + // Decay the peak signal + const int elapsedMs = m_peakLevelChanged.elapsed(); + const qreal decayAmount = m_peakDecayRate * elapsedMs; + if (decayAmount < m_peakLevel) + m_decayedPeakLevel = m_peakLevel - decayAmount; + else + m_decayedPeakLevel = 0.0; + + // Check whether to clear the peak hold level + if (m_peakHoldLevelChanged.elapsed() > PeakHoldLevelDuration) + m_peakHoldLevel = 0.0; + + update(); +} + +void LevelMeter::paintEvent(QPaintEvent *event) +{ + Q_UNUSED(event) + + QPainter painter(this); + painter.fillRect(rect(), Qt::black); + + QRect bar = rect(); + + bar.setTop(rect().top() + (1.0 - m_peakHoldLevel) * rect().height()); + bar.setBottom(bar.top() + 5); + painter.fillRect(bar, m_rmsColor); + bar.setBottom(rect().bottom()); + + bar.setTop(rect().top() + (1.0 - m_decayedPeakLevel) * rect().height()); + painter.fillRect(bar, m_peakColor); + + bar.setTop(rect().top() + (1.0 - m_rmsLevel) * rect().height()); + painter.fillRect(bar, m_rmsColor); +} |