Qt Reference Documentation

levelmeter.h Example File

demos/spectrum/app/levelmeter.h
 /****************************************************************************
 **
 ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
 ** All rights reserved.
 ** Contact: Nokia Corporation ([email protected])
 **
 ** 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."
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/

 #ifndef LEVELMETER_H
 #define LEVELMETER_H

 #include <QTime>
 #include <QWidget>

 /**
  * Widget which displays a vertical audio level meter, indicating the
  * RMS and peak levels of the window of audio samples most recently analysed
  * by the Engine.
  */
 class LevelMeter : public QWidget {
     Q_OBJECT
 public:
     LevelMeter(QWidget *parent = 0);
     ~LevelMeter();

     void paintEvent(QPaintEvent *event);

 public slots:
     void reset();
     void levelChanged(qreal rmsLevel, qreal peakLevel, int numSamples);

 private slots:
     void redrawTimerExpired();

 private:
     /**
      * Height of RMS level bar.
      * Range 0.0 - 1.0.
      */
     qreal m_rmsLevel;

     /**
      * Most recent peak level.
      * Range 0.0 - 1.0.
      */
     qreal m_peakLevel;

     /**
      * Height of peak level bar.
      * This is calculated by decaying m_peakLevel depending on the
      * elapsed time since m_peakLevelChanged, and the value of m_decayRate.
      */
     qreal m_decayedPeakLevel;

     /**
      * Time at which m_peakLevel was last changed.
      */
     QTime m_peakLevelChanged;

     /**
      * Rate at which peak level bar decays.
      * Expressed in level units / millisecond.
      */
     qreal m_peakDecayRate;

     /**
      * High watermark of peak level.
      * Range 0.0 - 1.0.
      */
     qreal m_peakHoldLevel;

     /**
      * Time at which m_peakHoldLevel was last changed.
      */
     QTime m_peakHoldLevelChanged;

     QTimer *m_redrawTimer;

     QColor m_rmsColor;
     QColor m_peakColor;

 };

 #endif // LEVELMETER_H
X

Thank you for giving your feedback.

Make sure it is related to this specific page. For more general bugs and requests, please use the Qt Bug Tracker.