Odd behaviour with QPen/QColor

[Perdrix]

I have a widget that is displayed on top of another widget (imageView), and has the following attributes set in the ctor:

        setAttribute(Qt::WA_TransparentForMouseEvents);
        setAttribute(Qt::WA_NoSystemBackground);
        setAttribute(Qt::WA_WState_ExplicitShowHide);

This code in its paintEvent:

        QPainter painter(this);
        QColor colour{ QColorConstants::Cyan };
        colour.setAlpha(128);
        QPen pen(colour, 1.0);

        if (pt1_ != pt2_)
        {
            QPointF p1 = imageView->imageToScreen(pt1_);
            if (p1.x() < 0.5) p1.rx() = 0.5;
            if (p1.y() < 0.5) p1.rx() = 0.5;
            QPointF p2 = imageView->imageToScreen(pt2_);
            if (p2.x() < 0.5) p2.rx() = 0.5;
            p2.ry()--;
            QPointF p3 = imageView->imageToScreen(pt3_);
            p3.rx()--;  p3.ry()--;
            QPointF p4 = imageView->imageToScreen(pt4_);
            if (p4.x() < 0.5) p4.rx() = 0.5;
            p4.ry()--;
            painter.drawLine(p1, p2);
            painter.drawLine(p2, p3);
            painter.drawLine(p3, p4);
            painter.drawLine(p4, p1);
        }

mostly works fine except that the line drawn is white and not semi-transparent???

Am I missing something obvious here?

Thanks
David

[jsulm]

@Perdrix said in Odd behaviour with QPen/QColor:

QPen pen(colour, 1.0);

You're not using pen anywhere as far as I can see...

[Perdrix]

@jsulm Yep you're right I did miss the obvious

Doh! Slap head!

painter.setPen(pen) would help a lot!