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// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
#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, &QTimer::timeout,
this, &LevelMeter::redrawTimerExpired);
m_redrawTimer->start(RedrawInterval);
}
LevelMeter::~LevelMeter() = default;
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);
}
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