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

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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();
}

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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);

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I use Qt 4.7.1 and Qwt 6.0.0

[Uwe]

From the tvplot example in SVN trunk:

QwtPlotRenderer renderer;
renderer.renderDocument(plot, "tvplot.pdf", QSizeF(300, 200), 85);

QwtPlotRenderer renderer;
renderer.renderDocument(plot, "tvplot.pdf", QSizeF(300, 200), 85);

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Uwe

[gkarthick5]

Thanks for the Reply. I tried that also. But getting the same result (everything other than the data plots are getting printed). Is there some problem when multiple histograms are enabled in the plot(i have around 16 of them). Also, is there any specific order in which the attaching or any other thing like that have to be done?
This is how i add the histograms to the plot

HistogramPlot *qp = new HistogramPlot;

HistogramPlot *qp = new HistogramPlot;

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int nValues = model->rowCount();
for(int v=0; v<nValues; v++)
{
	double *values = new double[nValues];
	for(int x=0; x<nValues; x++)
		values[x] = 0;
	values[v] = model->data(model->index(v, 1)).toDouble();
	Histogram *h = new Histogram(model->data(model->index(v, 0)).toString(),
		QColor(model->data(model->index(v,0), Qt::DecorationRole).toString()));
	h->setValues(nValues, values);
	h->attach(qp);
}
 
QwtLegend *legend = new QwtLegend;
qp->insertLegend(legend, QwtPlot::RightLegend);
fl->addWidget(qp, 1);

int nValues = model->rowCount();
for(int v=0; v<nValues; v++)
{
	double *values = new double[nValues];
	for(int x=0; x<nValues; x++)
		values[x] = 0;
	values[v] = model->data(model->index(v, 1)).toDouble();
	Histogram *h = new Histogram(model->data(model->index(v, 0)).toString(),
		QColor(model->data(model->index(v,0), Qt::DecorationRole).toString()));
	h->setValues(nValues, values);
	h->attach(qp);
}

QwtLegend *legend = new QwtLegend;
qp->insertLegend(legend, QwtPlot::RightLegend);
fl->addWidget(qp, 1);

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[Uwe]

Post a small compilable demo application and I will have a look at it.

Uwe

[gkarthick5]

Thanks, I was setting the transformation wrongly to use the plot's width and height instead of the number of bars and maxValue of the bars. Now its working.

[gkarthick5]

I realized the problem now. I was doing the drawing in the drawCanvas() method of my plot, while the renderDocument() actually calls drawItems().