Qt: Save QPainter Output in an SVG or Image File

To save what you paint in a Qt window to a file (SVG or image) is an easy and straightforward piece of code.

You create a QSvgGenerator or a QImage object.
Some initialization.
Paint into the object (treat it as an IODevice)
And  we are done.

Suppose that this is what I draw in my paint event:

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

void MainWindow::paintEvent(QPaintEvent *) {     QPainter painter;     painter.begin(this);           painter.setRenderHint(QPainter::Antialiasing);     paint(painter);           painter.end(); }   void MainWindow::paint(QPainter &painter) {     painter.setClipRect(QRect(0, 0, 200, 200));     painter.setPen(Qt::NoPen);     painter.fillRect(QRect(0, 0, 200, 200), Qt::gray);     painter.setPen(QPen(Qt::white, 4, Qt::DashLine));     painter.drawLine(QLine(0, 35, 200, 35));     painter.drawLine(QLine(0, 165, 200, 165)); }

If I want to save it into an SVG file, it would be something like this

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

void MainWindow::saveSvg() {     QString path = QFileDialog::getSaveFileName(this, tr("Save as SVG"),"", tr("SVG file (*.svg)"));       if (path.isEmpty())         return;       QSvgGenerator generator;     generator.setFileName(path);     generator.setSize(QSize(200, 200));     generator.setViewBox(QRect(0, 0, 200, 200));     generator.setTitle(tr("SVG Generator Example Drawing"));     generator.setDescription(tr("An SVG drawing created by the SVG Generator "                              "Example provided with Qt."));     QPainter painter;     painter.begin(&generator);     paint(painter);     painter.end(); }

If I want to save it into an image file, it would be something like this.

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

void MainWindow::savePng() {     QString path = QFileDialog::getSaveFileName(this, tr("Save as image"), "", tr("PNG file (*.png)"));       if (path.isEmpty())         return;       QImage img(200, 200, QImage::Format_ARGB32);       QPainter painter;     painter.begin(&img);     paint(painter);     painter.end();       img.save(path); }

Note that if you  replace

?

1 2 3 4 5 6

QImage img(200, 200, QImage::Format_ARGB32);   QPainter painter; painter.begin(&img); paint(painter); painter.end();

with

?

1 2 3

QImage img(this->size(), QImage::Format_ARGB32); QPainter painter(&img); this->render(&painter);

you'll be taking a screenshot of widget content into an image.


References:
SVG Generator Example
Capture Qt widget as an image file