Graph plotting

[steg90]

Hi,

I've come up with the following simple code to draw a x,y graph plot ( the graph is updated in real-time ) :

void PlotterView::paintEvent( QPaintEvent *event)
{
	QPainter painter(this);
 
	painter.setWindow( 0, 0, 800, 200 );
 
	painter.setRenderHint( QPainter::Antialiasing, true);
	painter.setPen(QPen(Qt::black, 1, Qt::SolidLine, Qt::RoundCap, Qt::MiterJoin));
 
	int nGridStep = 20;
	for( int x = 0; x <= 800 / nGridStep; x ++ )
	{
		painter.drawLine( x * nGridStep, 0, x * nGridStep, 200 );	
	}
	for( int y = 0; y <= 200 / nGridStep; y ++ )
	{
		painter.drawLine( 0, y * nGridStep, 800, y * nGridStep );	
	}
 
	painter.setPen(QPen(Qt::red, 3, Qt::SolidLine, Qt::RoundCap, Qt::MiterJoin));
	int nSpace = 0;
	int nSpace2 = 0;
	for( int i = 0; i < 48; i ++ )  // size of linear buffer
	{
		nSpace += nGridStep;
		painter.drawLine( nSpace2, 200 - m_GraphArray[ i ], nSpace, 200 - m_GraphArray[ i + 1 ] );
		nSpace2 += nGridStep;
	}
}

void PlotterView::paintEvent( QPaintEvent *event)
{
	QPainter painter(this);

	painter.setWindow( 0, 0, 800, 200 );

	painter.setRenderHint( QPainter::Antialiasing, true);
	painter.setPen(QPen(Qt::black, 1, Qt::SolidLine, Qt::RoundCap, Qt::MiterJoin));

	int nGridStep = 20;
	for( int x = 0; x <= 800 / nGridStep; x ++ )
	{
		painter.drawLine( x * nGridStep, 0, x * nGridStep, 200 );	
	}
	for( int y = 0; y <= 200 / nGridStep; y ++ )
	{
		painter.drawLine( 0, y * nGridStep, 800, y * nGridStep );	
	}

	painter.setPen(QPen(Qt::red, 3, Qt::SolidLine, Qt::RoundCap, Qt::MiterJoin));
	int nSpace = 0;
	int nSpace2 = 0;
	for( int i = 0; i < 48; i ++ )  // size of linear buffer
	{
		nSpace += nGridStep;
		painter.drawLine( nSpace2, 200 - m_GraphArray[ i ], nSpace, 200 - m_GraphArray[ i + 1 ] );
		nSpace2 += nGridStep;
	}
}

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m_GraphArray is an array of unsigned ints which gets updated as a 'rolling buffer', at the moment, the graph is plotting randomly within a timer :

void PlotterView::timerEvent(QTimerEvent *event)
{
	memcpy( m_GraphArray, &m_GraphArray[1], 50 * sizeof(unsigned int) );   // move entire array left one
	m_GraphArray[50] = qrand() % 200;     
	repaint();
}

void PlotterView::timerEvent(QTimerEvent *event)
{
	memcpy( m_GraphArray, &m_GraphArray[1], 50 * sizeof(unsigned int) );   // move entire array left one
	m_GraphArray[50] = qrand() % 200;     
	repaint();
}

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What I like about this, is the fact that if the user stretches the window this widget is in, the graph also stretches etc...

Ok, now my question, finally... If I wanted to have other controls within the window the graph is in, how do I do it so when the user stretches the window, the graph doesn't go over these controls? Does this make sense?!

I was thinking I may have a subclassed label or something and use that to draw the graph on and just drop this onto a new window?

Regards,
Steve

PS - If there is also a better way of drawing graphs instead of using the QPainter class I'd be very interested.