Qt How to set focus on a QRect - c++

Question

I have created a Qwidget with a QRect. Now I would like to move this Rect with my keyboard. Which does not work. When trying with a mousePressEvent instead of the keyPressEvent, everything is working fine though. There are no Focuses yet set, which probably is the problem here. But it's the first time I have to work with those and I just can't figure out what to do and how to use them, even after searching online for the last hours.
I tried putting setFocusPolicy(Qt::StrongFocus) in my widgets constructor amongst other things, but nothing has worked so far. Maybe I'm just blind to an obvious solution, but please help? Thanks alot already
my paint event:
void zeichenFeld::paintEvent(QPaintEvent *event)
{
QPainter painter;
painter.begin (this);
//Avatar:
QRect rectAv=QRect(xAv, yAv, 20,20);
painter.fillRect(rectAv, Qt::BrushStyle::SolidPattern);
painter.fillRect(rectAv, colorAv);
painter.drawRect(rectAv);
painter.end();
}
void zeichenFeld::keyPressEvent(QKeyEvent *event)
{
if(event->key()==Qt::Key_A){
xAv-=10;
}
if(event->key()==Qt::Key_D){
xAv+=10;
}
update();
}
void zeichenFeld::mousePressEvent(QMouseEvent *event){
if(event->button()==Qt::LeftButton)
{
xAv-=25;
}
if(event->button()==Qt::RightButton)
{
xAv+=25;
}
update();
}
header:
protected:
void paintEvent(QPaintEvent *event);
void keyPressEvent(QKeyEvent *event);
void mousePressEvent(QMouseEvent *event);
Edit: i simply added the setFocusPolicy(Qt::StrongFocus); to the wrong contructor. Working now

Answer 1

a QRect is not a visual class, so if you used the PaintEvent to draw a rectangle, then you need to come up with your special way to handle that in the mouse press event.
something like:
YourClass.h
protected:
void mousePressEvent(QMouseEvent *ev) override;
void mouseMoveEvent(QMouseEvent *ev) override;
void mouseReleaseEvent(QMouseEvent *ev) override;
private:
QRect _myRect;
YourClass.cpp
void YourClass::mousePressEvent(QMouseEvent *ev) {
if (_myRect.contains(ev->localPos())){
_isRectSelected = true;
}
}
void YourClass::mouseMoveEvent(QMouseEvent *ev) {
if (_isRectSelected) {
_myRect->setX(ev->localPos().x());
_myRect->setY(ev->localPos().y());
}
}
void YourClass::mouseReleaseEvent(QMouseEvent *ev) {
if (_isRectSelected) {
_isRectSelected = false;
}
}
but I wouldn't reccomend that. Try to use QGraphicsView with QGraphicsRectItem as it's a visual class. it knows how to paint itself and it also has mouse handling.
Or even better, Qml.