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qtlinebounding-boxqpainter

Determine bounding rect of line in Qt

I am drawing a line using QPainterPath between two points as follows:

QPainterPath line;
line.moveTo(start_p);
line.lineTo(end_p);

QPen paintpen(Qt::black);
paintpen.setWidth(1);
painter->setRenderHint(QPainter::Antialiasing);
painter->setBrush(Qt::SolidPattern);
painter->setPen(paintpen);
painter->drawPath(line);

I have defined bounding rect as:

QRectF Line::boundingRect() const
{
 return QRectF(start_p.x(), start_p.y(), end_p.x(), end_p.y());
}

I get line painted correctly when:

start_p.x() < end_p.x()

and 

start_p.y() < end_p.y()

How should the bounding rect be defined so that line is drawn correctly irrespective of the relationship between the coordinates of two points(start_p and end_p)?

Solution

  • You might try to normalize your rectangle:

    QRectF Line::boundingRect() const
{
    return QRectF(start_p.x(), start_p.y(), end_p.x(), end_p.y()).normalized();
}