How to create image file from QGraphicsScene/QGraphicsView ?

Image file from QGraphicsScene/QGraphicsView:

QGraphicsView* view = new QGraphicsView(scene,this);
QString fileName = "file_name.png";
QPixmap pixMap = view->grab(view->sceneRect().toRect());
pixMap.save(fileName);
//Uses QWidget::grab function to create a pixmap and paints the QGraphicsView inside it.

Give the function QGraphicsScene::render():

QImage image(fn);
QPainter painter(&image);
painter.setRenderHint(QPainter::Antialiasing);
scene.render(&painter);
image.save("file_name.png")

The following alternative code is :

scene->clearSelection();         // Selections would also render to the file
scene->setSceneRect(scene->itemsBoundingRect());        // Re-shrink the scene to it's bounding contents
QImage image(scene->sceneRect().size().toSize(), QImage::Format_ARGB32);         // Create the image with the exact size of the shrunk scene
image.fill(Qt::transparent);         // Start all pixels transparent
 
QPainter painter(&image);
scene->render(&painter);
image.save("file_name.png");

The grabWidget is derogat and to use a QFileDialog:

QString fileName= QFileDialog::getSaveFileName(this, "Save image", QCoreApplication::applicationDirPath(), "BMP Files (*.bmp);;JPEG (*.JPEG);;PNG (*.png)" );
   if (!fileName.isNull())
   {
       QPixmap pixMap = this->ui->graphicsView->grab();
       pixMap.save(fileName);
   }