Selection precision problems with QGraphicsScene and scaled content?

Hi,

I got precision problems with the selection in a QGraphicsScene. It is quiet simple to reproduce. Here is my code...

Code:

---

//----------------------------------------------------------------------------
//  Includes
//----------------------------------------------------------------------------
 
#include <QApplication>
#include <QGraphicsView>
#include <QGraphicsRectItem>
#include <QHBoxLayout>
 
//----------------------------------------------------------------------------
 
class MyFooView : public QGraphicsView
{
public:
    MyFooView(QWidget* parent = NULL) :
    QGraphicsView(parent)
    {
        setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
    }
    MyFooView(QGraphicsScene* scene, QWidget* parent = NULL) :
    QGraphicsView(scene, parent)
    {
        setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
        scale(20.0, 20.0);
    }
	~MyFooView(void)
    {
    }
};
 
int main(int argv, char **args)
{
    QApplication app(argv, args);
 
    QGraphicsScene* scene = new QGraphicsScene();
    scene->setSceneRect(QRectF(0, 0, 5000, 5000));
 
    MyFooView* view = new MyFooView(scene);
 
    QGraphicsRectItem* dummy = new QGraphicsRectItem(50.0, 50.0, 30.0, 30.0);
    dummy->setBrush(QBrush(Qt::red));
    dummy->setAcceptHoverEvents(true);
    dummy->setFlag(QGraphicsItem::ItemIsSelectable, true);
    dummy->setFlag(QGraphicsItem::ItemIgnoresTransformations, true);
    scene->addItem(dummy);
 
    view->centerOn(0.0, 0.0);
 
    QHBoxLayout* l = new QHBoxLayout;
    l->addWidget(view);
 
    QWidget* w = new QWidget();
    w->setLayout(l);
    w->show();
 
    return app.exec();
}

---

Run the program. For me it is possible to select the rect item a bit above and left of its shape. Can someone confirm and tell me how to solve it?

Best regards,
Marcus

The problem you are seeing could be related to this bug.

https://bugreports.qt-project.org/browse/QTBUG-17985

Quote:

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Originally Posted by steno

The problem you are seeing could be related to this bug.

https://bugreports.qt-project.org/browse/QTBUG-17985

---

Thanks a lot. With the proposed fix everything works as expected!