QGraphicsView draws 1pt text incorrectly

The following example shows that sometimes the position of text drawn is shifted by 1pixel:

#include <QGraphicsView>
#include <QGraphicsScene>
#include <QGraphicsItem>
#include <QTransForm>

#include <QApplication>
#include <iostream>

class TextItem : public QGraphicsItem
{
public:
TextItem(int y, int size)

{ text = "Only"; pointSize = 1; pt = QPointF(0,y); }

QRectF boundingRect() const

{ QFont font(qApp->font()); font.setPointSizeF(pointSize); QFontMetrics fm(font); QRectF r = fm.boundingRect(text); r.moveTopLeft(QPointF(pt.x(),pt.y())); return r; }

void paint(QPainter *painter,const QStyleOptionGraphicsItem *option,QWidget *widget)

{ painter->setPen(Qt::red); QFont font(qApp->font()); font.setPointSizeF(pointSize); painter->setFont(font); painter->drawText(QPointF(pt.x(),pt.y()+pointSize), text); }

QPointF pt;
QString text;
int pointSize;
};

int main(int argc, char *argv[])
{

QApplication app(argc,argv);

QGraphicsView v;
QGraphicsScene *scene = new QGraphicsScene();
v.setScene(scene);

QTransform t;
t.scale(25.3,25.3);
v.setTransform(t);

int curY = 0;
for (double i = 1; i < 50; i *= 1.05)

{ TextItem *item = new TextItem(curY,i); scene->addItem(item); curY += i; }

v.setBackgroundBrush(Qt::black);
v.show();
return app.exec();
}