Printing QGraphicsScene with normalized coordinate system

[IvanM1976]

Hello,

I'm trying to using QGraphicsView/QGraphicsScene to render 2D objects using a normalized (right hand) coordinate system and a specific logical unit 1px=0.01 mm.
This is the same resolution you get setting MM_HIMETRIC with MFC.

For the screen I resolved this way:

QGraphicsView* pView = new QGraphicsView();
QGraphicsScene* pScene = new QGraphicsScene(pView);
pScene->setSceneRect(0,0,21000,-29700);
pView->setScene(pScene);
double scaleX = ((double)pView->physicalDpiX())/2540.0;
double scaleY = ((double)pView->physicalDpiY())/2540.0;
pView->scale(scaleX,scaleY);
QTransform tr;
tr = tr.scale(1.0,-1.0);
pView->setTransform(tr,true);
pScene->addLine(100,-1000,1100,-1000,QPen(Qt::black,10));

with the code above, the line will be long 1cm.

Now I find some problems in printing with this coordinate system.

QPrinter printer(QPrinter::HighResolution);

printer.setPageSize(QPrinter::A4);

if (QPrintDialog(&printer).exec() == QDialog::Accepted) {
QPainter painter(&printer);
//......initialization of viewport/ window here?????
painter.setRenderHint(QPainter::Antialiasing);
pScene->render(&painter);
}

How should I set viewport/Window of painter in order to get the same results of the screen rendering?