QChart in a QTextDocument - c++

Question

I want to generate a pdf report containing text and a QChart. I currently use the QTextDocument and add the chart into it as an image, then I use the QPdfWriter to export to pdf.
#include <QtGui>
#include <QtCore>
#include <QApplication>
#include <QtCharts/QChartView>
#include <QtCharts/QLineSeries>
using namespace QtCharts;
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
// Create a chart
QLineSeries *series = new QLineSeries();
series->append(0,0);
series->append(1,1);
QChart *chart = new QChart();
chart->addSeries(series);
chart->createDefaultAxes();
chart->axisX()->setTitleText(QString("x [m]"));
chart->axisY()->setTitleText(QString("y [m]"));
chart->setTitle("Simple chart example");
chart->resize(500,500);
// Paint the chart into an image
QImage img(500,500,QImage::Format_RGB32);
QPainter painter(&img);
QChartView *chartView = new QChartView(chart);
chartView->setRenderHint(QPainter::Antialiasing);
chartView->show();
chartView->render(&painter);
// Set up pdf writer
QString filename = "myfile.pdf";
QPdfWriter writer(filename);
writer.setPageSize(QPagedPaintDevice::A4);
// Create the document
QTextDocument doc;
QTextCursor cursor(&doc);
cursor.insertText(QString("some text\n"));
cursor.insertImage(img);
// Print the document
doc.print(&writer);
return a.exec();
}
Although it works, I would like to avoid converting the chart into an image because it messes up the image quality. Is there a way to do it?

Answer 1

Here is a workaround, if the image quality is really what matters : you can use QPainter directly on the TextDocument. It requires more work and adjustement, but the quality is not lost.
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
// Create a chart
QLineSeries *series = new QLineSeries();
series->append(0,0);
series->append(1,1);
QChart *chart = new QChart();
chart->addSeries(series);
chart->createDefaultAxes();
chart->axisX()->setTitleText(QString("x [m]"));
chart->axisY()->setTitleText(QString("y [m]"));
chart->setTitle("Simple chart example");
chart->resize(500,500);
QChartView *chartView = new QChartView(chart);
chartView->setRenderHint(QPainter::TextAntialiasing);
chartView->show();
// Set up pdf writer
QString filename = "myfile.pdf";
QPdfWriter writer(filename);
writer.setPageSize(QPagedPaintDevice::A4);
// Create the document
QTextDocument doc;
QPainter painter(&writer);
QFont font = painter.font();
font.setPixelSize(200);
painter.setFont(font);
painter.drawText(QPoint(700,100),"Some text");
chartView->render(&painter);
doc.drawContents(&painter);
return a.exec();
}