Drawing QRubberBands with variabe size, but fixed aspect ratio: how to do it?

[BwvB]

Hi, I am using the QRubberBand class to draw a rectangular shape on the screen.

By trapping the mouse position when the mouse is pressed, and connecting mouse move events to the setGeometry function I can move the mouse around, with the rubberband following the mouse cursor in a rectangular shape. This all works ok.

I would like to constrain the mouse movements such that the rectangular rubber band still is of variable size, but always has a fixed aspect ratio. This could be handy, for instance, when cropping an image.
Are there any suggestions how I could achieve such a constraint?

Kind Regards,
Bertwim

[BwvB]

@jsulm said in Drawing QRubberBands with variabe size, but fixed aspect ratio: how to do it?:

rubberBand->setGeometry(QRect(origin, event->pos()).normalized());

Thanks. It is indeed as easy as you indicated!
Regards
Bertwim

[jsulm]

@BwvB You could calculate the size so that it has the aspect ratio you want in mouseMoveEvent (see https://doc.qt.io/qt-6/qrubberband.html):

void Widget::mouseMoveEvent(QMouseEvent *event)
{
    // Here calculate the QRect the way you need it
    rubberBand->setGeometry(QRect(origin, event->pos()).normalized());
}

[BwvB]

@jsulm said in Drawing QRubberBands with variabe size, but fixed aspect ratio: how to do it?:

rubberBand->setGeometry(QRect(origin, event->pos()).normalized());

Thanks. It is indeed as easy as you indicated!
Regards
Bertwim