Qt window resize aspect ratio 1:1 - qt

Question

I want to resize the app window proportionally 1:1. I tried to change it inside the ResizeEvent, but then I got the window flickering. Now my code looks like this, but it doesn't work.
filterobject.h:
class FilterObject:public QObject{
public:
QWidget *target = nullptr;//it holds a pointer to target object
int goalHeight=0;
FilterObject(QObject *parent=nullptr):QObject(parent){}//uses QObject constructor
bool eventFilter(QObject *watched, QEvent *event) override;//and overrides eventFilter function
};
widget.h:
namespace Ui {
class Widget;
}
class Widget : public QWidget
{
Q_OBJECT
public:
explicit Widget(QWidget *parent = nullptr);
virtual int heightForWidth ( int w ) const { return w*9/16;}
//virtual void resizeEvent(QResizeEvent *event) override;
~Widget();
private:
Ui::Widget *ui;
};
widget.cpp:
Widget::Widget(QWidget *parent) :
QWidget(parent),
ui(new Ui::Widget)
{
ui->setupUi(this);
}
Widget::~Widget()
{
delete ui;
}
void QWidget::resizeEvent(QResizeEvent *event){
FilterObject *filter = new FilterObject();
QWidget *targetWidget = new QWidget();
filter->target=targetWidget;
targetWidget->installEventFilter(filter);
}
bool FilterObject::eventFilter(QObject *watched, QEvent *event) {
if(watched != target){//checks for correct target object.
return false;
}
if(event->type() != QEvent::Resize){//and correct event
return false;
}
QResizeEvent *resEvent = static_cast<QResizeEvent*>(event);
goalHeight = 9*resEvent->size().width()/16;
if(target->height()!=goalHeight){
target->setFixedHeight(goalHeight);
}
return true;
};
Perhaps this code will work, but my condition if(event->type() != QEvent::Resize) does not work .. Any ideas?

Answer 1

You have some problems in your code. First of all you should install event filter once e.g in your constructor. You create an object of event filter and install it every time resizeEvent is triggered which is wrong. Also you are installing event filter on the wrong object (a new QWidget). So remove the resizeEvent function and insert in the constructor of Widget:
FilterObject *filter = new FilterObject();
filter->target=this;
installEventFilter(filter);