Merge demos and examples.

Change-Id: I65ba412ef5207a71bf8763983b28672d1743f4b8
Reviewed-on: http://codereview.qt.nokia.com/1398
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Casper van Donderen <casper.vandonderen@nokia.com>

examples/multimedia/spectrum/app/levelmeter.cpp

@@ -0,0 +1,142 @@
+/****************************************************************************
+**
+** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** 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 Nokia Corporation 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);
+}