audiolevel.cpp Example File

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 #include "audiolevel.h"
 #include <QPainter>

 AudioLevel::AudioLevel(QWidget *parent)
   : QWidget(parent)
 {
     setMinimumHeight(15);
     setMaximumHeight(50);
 }

 void AudioLevel::setLevel(qreal level)
 {
     if (m_level != level) {
         m_level = level;
         update();
     }
 }

 void AudioLevel::paintEvent(QPaintEvent *event)
 {
     Q_UNUSED(event);

     QPainter painter(this);
     // draw level
     qreal widthLevel = m_level * width();
     painter.fillRect(0, 0, widthLevel, height(), Qt::red);
     // clear the rest of the control
     painter.fillRect(widthLevel, 0, width(), height(), Qt::black);
 }