Printing in custom size

[wazzdaman]

Hello,

I have a QGraphicsScene with scene size of 4"x6" and I'd like print it in the same size. Unfortunately it gets scaled up to the paper size. How can I print it with the correct size (regardless of the used paper size)?

When I tried to set up the custom page size I got only an empty page :(

Win 10, Qt 5.15.2

QPageSize pageSize = QPageSize(QSizeF(4.0, 6.0), QPageSize::Unit::Inch, "4x6 in page", QPageSize::SizeMatchPolicy::ExactMatch);
bool result = printer.setPageSize(pageSize);
qDebug() << "page set result" << result; // true 
qDebug() << printer.pageLayout().pageSize().name(); // "4x6 in page"
qDebug() << printer.pageLayout().pageSize().id(); // 30 - ID of custom page size
printer.setPageOrientation(QPageLayout::Landscape);
QPainter painter(&printer);
painter.setRenderHint(QPainter::Antialiasing);
workScene->render(&painter); 

Any help is appreciated. Thanks!

[SGaist]

Hi and welcome to devnet,

What do you get if you paint a rectangle rather than your scene ?

[wazzdaman]

@SGaist If I replace the line

workScene->render(&painter); 

with

painter.begin(printer);
painter.drawRect(QRectF(0, 0, 100, 100));
painter.end();

then I get a little rectangle in the corner, although it complains that

QPainter::begin: A paint device can only be painted by one painter at a time.

[SGaist]

Since you passed printer to QPainter's constructor, you shall not call begin, just end.

[wazzdaman]

@SGaist It fixed that warning message, thanks!

I think I've found the solution for my problem: I should pass the correct size for target in QGraphicsScene::render() and it will render the scene correctly regardless of the paper size. Is this correct?

[SGaist]

Sounds good.