Qt rubberband not being drawn - c++

Question

I am attempting to implement a rubberband. Here is my code.
void TOTMain::mousePressEvent(QMouseEvent * event)
{
QPoint origin = event->pos();
_selectionSquare = new QRubberBand(QRubberBand::Rectangle, this);
_selectionSquare->setGeometry(QRect(origin, QSize()));
_selectionSquare->raise();
_selectionSquare->show();
}
void TOTMain::mouseMoveEvent(QMouseEvent *event)
{
QPoint origin = event->pos();
_selectionSquare->setGeometry(QRect(origin, event->pos()).normalized());
}
void TOTMain::mouseReleaseEvent(QMouseEvent *event)
{
_selectionSquare->hide();
// determine selection, for example using QRect::intersects()
// and QRect::contains().
}
The issue is that the band is not being drawn. I confirm it is being constructed and persists through the dragging, but no rendering.
Any ideas appreciated.

Answer 1

Take a look at your mouseMoveEvent implementation...
void TOTMain::mouseMoveEvent(QMouseEvent *event)
{
QPoint origin = event->pos();
_selectionSquare->setGeometry(QRect(origin, event->pos()).normalized());
}
You're setting the geometry of the rubber band to QRect(origin, event->pos()), but you've previously set origin = event->pos() so the top-left and bottom-right corners of the rectangle are the same.
Make origin a member variable variable of your class (untested)...
class TOTMain: public QWidget {
public:
protected:
virtual void mousePressEvent (QMouseEvent *event) override
{
_origin = event->pos();
_selectionSquare = new QRubberBand(QRubberBand::Rectangle, this);
_selectionSquare->setGeometry(QRect(_origin, QSize()));
_selectionSquare->raise();
_selectionSquare->setStyleSheet("{ background-color : red; }");
_selectionSquare->show();
}
virtual void mouseMoveEvent (QMouseEvent *event) override
{
_selectionSquare->setGeometry(QRect(_origin, event->pos()).normalized());
}
virtual void mouseReleaseEvent (QMouseEvent *event) override
{
_selectionSquare->hide();
// determine selection, for example using QRect::intersects()
// and QRect::contains().
}
private:
QPoint _origin;
QRubberBand *_selectionSquare = nullptr;
};