paint Rect sometimes missing one border

[stella1016]

I have a QGraphicsRectItem. In its paint() method:

painter->setPen(QPen(Qt::red, 1, Qt::SolidLine));
painter->setBrush(QBrush(Qt::gray, Qt::Dense4Pattern));
painter->drawRect(draw_rect);

painter->setPen(QPen(Qt::red, 1, Qt::SolidLine));
painter->setBrush(QBrush(Qt::gray, Qt::Dense4Pattern));
painter->drawRect(draw_rect);

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QRectF Myclass::boundingRect() const
{ 
	qreal adjust = 1.0;
	QRectF result(m_rect.topLeft().rx() - adjust/2, m_rect.topLeft().ry() - adjust/2,
		m_rect.width() + adjust, m_rect.height() + adjust);
 
	return result;
}

QRectF Myclass::boundingRect() const
{ 
	qreal adjust = 1.0;
	QRectF result(m_rect.topLeft().rx() - adjust/2, m_rect.topLeft().ry() - adjust/2,
		m_rect.width() + adjust, m_rect.height() + adjust);

	return result;
}

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Most of the time, the rectangle is painted correctly. But after resize, sometimes it will miss the red line boarder, for example the left-side edge is not painted.

I tried with following: doesn't work:

QRectF Myclass::boundingRect() const
{ 
	qreal adjust = 1.0;
	QRectF result(m_rect.topLeft().rx() - adjust, m_rect.topLeft().ry() - adjust,
		m_rect.width() + adjust, m_rect.height() + adjust);
 
	return result;
}

QRectF Myclass::boundingRect() const
{ 
	qreal adjust = 1.0;
	QRectF result(m_rect.topLeft().rx() - adjust, m_rect.topLeft().ry() - adjust,
		m_rect.width() + adjust, m_rect.height() + adjust);

	return result;
}

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Any one know this problem?