Printing QwtPlot on QPrinter

[gkarthick5]

I have a QwtPlot in which i add multiple Histograms (Histogram is the class from the "tvplot" example). When i try to print the plot to a QPrinter ( i tried with a pdf and jpeg file), i get the axes, labels, title and legend printed. But no data. What should i do to get the bars also printed?

class HistogramPlot: public QwtPlot

class HistogramPlot: public QwtPlot

To copy to clipboard, switch view to plain text mode 

void HistogramPlot::writeToPrinter(QPrinter* printer)
{
	QwtPlotRenderer rend;
	QPainter painter(printer);
 
	rend.setDiscardFlag(QwtPlotRenderer::DiscardNone, true);
	rend.setDiscardFlag(QwtPlotRenderer::DiscardBackground, true);
 
	QwtScaleMap *maps = new QwtScaleMap[this->axisCnt];
	QwtScaleTransformation* xx = new QwtScaleTransformation(QwtScaleTransformation::Linear);
	for(int axis = 0; axis< this->axisCnt; axis++)
		maps[axis].setTransformation(xx);
	rend.render(this, &painter, printer->pageRect());
 
	painter.end();
}

void HistogramPlot::writeToPrinter(QPrinter* printer)
{
	QwtPlotRenderer rend;
	QPainter painter(printer);

	rend.setDiscardFlag(QwtPlotRenderer::DiscardNone, true);
	rend.setDiscardFlag(QwtPlotRenderer::DiscardBackground, true);

	QwtScaleMap *maps = new QwtScaleMap[this->axisCnt];
	QwtScaleTransformation* xx = new QwtScaleTransformation(QwtScaleTransformation::Linear);
	for(int axis = 0; axis< this->axisCnt; axis++)
		maps[axis].setTransformation(xx);
	rend.render(this, &painter, printer->pageRect());

	painter.end();
}

To copy to clipboard, switch view to plain text mode 

HistogramPlot *qp = new HistogramPlot;
//...(Other Code Here)
QPrinter printer;
printer.setOrientation(QPrinter::Portrait);
printer.setOutputFormat(QPrinter::PdfFormat);
printer.setOutputFileName("temp.pdf");
printer.setPageSize(QPrinter::A4);
qp->writeToPrinter(&printer);

HistogramPlot *qp = new HistogramPlot;
//...(Other Code Here)
QPrinter printer;
printer.setOrientation(QPrinter::Portrait);
printer.setOutputFormat(QPrinter::PdfFormat);
printer.setOutputFileName("temp.pdf");
printer.setPageSize(QPrinter::A4);
qp->writeToPrinter(&printer);

To copy to clipboard, switch view to plain text mode 

I use Qt 4.7.1 and Qwt 6.0.0