How to create image file from QGraphicsScene/QGraphicsView? - c++

Question

Given a QGraphicsScene, or QGraphicsView, is it possible to create an image file (preferably PNG or JPG)? If yes, how?

Answer 1

After just dealing with this problem, there's enough improvement here to warrant a new answer:
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");

Answer 2

I have not tried this, but this is the idea of how to do it.
You can do this in several ways
One form is as follows:
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.
The other is to use the render function QGraphicsScene::render():
QImage image(fn);
QPainter painter(&image);
painter.setRenderHint(QPainter::Antialiasing);
scene.render(&painter);
image.save("file_name.png")

Answer 3

grabWidget is deprecated, use grab. And you can 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);
}