Drawing directly with QPainter and drawing QPixmap give different results

[mdma2]

There's a simple class based on QQuickPaintedItem:

class PaintedItem : public QQuickPaintedItem
{
    Q_OBJECT
public:
    PaintedItem();
    void paint(QPainter *painter) override;
};

// ...

PaintedItem::PaintedItem()
{
    setRenderTarget(QQuickPaintedItem::FramebufferObject);
}

void PaintedItem::paint(QPainter *painter)
{
    painter->drawRect(0, 0, 150, 150);

    QPixmap* m_pixmap = new QPixmap(width(), height());
    m_pixmap->fill(QColor("transparent"));

    QPainter painter2(m_pixmap);
    painter2.setPen(QColor("red"));
    painter2.drawRect(0, 0, 150, 150);

    painter->drawPixmap(0, 0, *m_pixmap);
}

The paint() function just does two things: draw a rectangle directly with QPainter and draw the QPixmap containing the same rectangle. But if I set the render target as FramebufferObject in the constructor, those rectangles doesn't match for some reason. If I comment this string, everything's OK.

With FramebufferObject

Without FramebufferObject

Could you please explain me why does it happen and how to deal with it?

[Diracsbracket]

@mdma2
Can you post the full code of this short example, so that it can be tried out immediately using simple copy/paste...