timeline

[franco.amato]

Hi to all, I'm developing an audio editor that at the moment has basic functionalities as draw the sound waveform, play the sound.
I would implement a time line ( a moving vertical line ) that give to the user an idea of which part of the sound is playing.
In the paintEvent I have to draw the waveform ( cached in a QImage ) and the time line.

This is my paintEvent

void WaveWidget::paintEvent( QPaintEvent* pe )
{
	// Update the ev->rect area with the wave from the rendered QPixmap here
 
	if( m_waveCachePixmap.isNull() )
	{
		updateWave();
	}
 
	QPainter p( this );
	QPen pen = QPen(Qt::blue, 1);
	p.setRenderHint( QPainter::Antialiasing, true );
	p.drawImage( 0, 0, m_waveCachePixmap );
 
	QRect& rect = QRect(pe->rect());
	p.setPen(pen);
 
	p.drawLine( rect.x(), 0, rect.x(), height()  );
}

void WaveWidget::paintEvent( QPaintEvent* pe )
{
	// Update the ev->rect area with the wave from the rendered QPixmap here

	if( m_waveCachePixmap.isNull() )
	{
		updateWave();
	}

	QPainter p( this );
	QPen pen = QPen(Qt::blue, 1);
	p.setRenderHint( QPainter::Antialiasing, true );
	p.drawImage( 0, 0, m_waveCachePixmap );

	QRect& rect = QRect(pe->rect());
	p.setPen(pen);
    
	p.drawLine( rect.x(), 0, rect.x(), height()  );
}

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I also have to delete the previous line before to draw the new? Or the final result is a growing rectangle. How can I do?

Best,
Franco