resizing widgets depending on a main widget size

[luf]

I'm trying to make a custom widget get it's size (fixed size) set depending on the size of a stacked widget.

I pick up the resize in resizeEvent of the main widget, and emit a signal to tell the other widget to resize. The problem is that when the custom widget has large fixed size, and I try to make the window smaller, it doesn't allow to scale/resize down properly. It works if I scale down several times, but that isn't a good solution.

I've figured out that I really should set the size before the resizeevent, as when that is called, the layout is already done. I just don't figure out what event it should be done in.

I tried implementing the following, as an small example.

custom.h:

class QCustomMainPage : QWidget
{
    public:
        QCustomMainPage(QWidget *parent)
    protected:
        void resizeEvent ( QResizeEvent *re );
    signals:
        void sizeChange(QSize size);
};
 
class QCustomResizeWidget : QFrame
{
    public:
        QCustomResizeWidget (QWidget *parent)
    public slots:
        void sizeChangeSlot(QSize size);
    protected:
        QSize sizeHint(void) const;
        QSize minimumSizeHint(void) const;
        QSize currentsize;
};

class QCustomMainPage : QWidget
{
    public:
        QCustomMainPage(QWidget *parent)
    protected:
        void resizeEvent ( QResizeEvent *re );
    signals:
        void sizeChange(QSize size);
};

class QCustomResizeWidget : QFrame
{
    public:
        QCustomResizeWidget (QWidget *parent)
    public slots:
        void sizeChangeSlot(QSize size);
    protected:
        QSize sizeHint(void) const;
        QSize minimumSizeHint(void) const;
        QSize currentsize;
};

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custom.cpp

QCustomResizeWidget::QCustomResizeWidget(QWidget *parent):QFrame (parent){
    QLabel *label1 = new QLabel("label1");
    QLabel *label2 = new QLabel("label2");
    QVBoxLayout *clayout = new QVBoxLayout(this);
    clayout->addWidget(label1);
    clayout->addWidget(label2);
}
 
void QCustomResizeWidgetsize::ChangeSlot(QSize size){
    currentsize = QSize(size.width()/10, size.width()/10); // keep it square
    this->setFixedSize(currentsize);
}
QSize QCustomResizeWidgetsize::sizeHint(void) const{
    return this->currentsize;
}
QSize minimumSizeHint(void) const{
    // return this->currentsize;
    return QSize(1,1); // allow widget to resize down to 1,1 (to get this partially working)
}
 
QCustomMainPage::QCustomMainPage(QWidget *parent) : QWidget(parent){
    QCustomResizeWidget *customwidget1 = new QCustomResizeWidget;
      connect(this, SIGNAL(sizeChange(QSize)), customwidget1, SLOT(ChangeSlot(QSize)));
    QCustomResizeWidget *customwidget2 = new QCustomResizeWidget;
      connect(this, SIGNAL(sizeChange(QSize)), customwidget1, SLOT(ChangeSlot(QSize)));
    QCustomResizeWidget *customwidget3 = new QCustomResizeWidget;
      connect(this, SIGNAL(sizeChange(QSize)), customwidget1, SLOT(ChangeSlot(QSize)));
    QCustomResizeWidget *customwidget4 = new QCustomResizeWidget;
      connect(this, SIGNAL(sizeChange(QSize)), customwidget1, SLOT(ChangeSlot(QSize)));
 
    QGridLayout *grid = new QGridLayout(this);
    grid->addWidget(customwidget1, 0,0);
    grid->addWidget(customwidget1, 0,1);
    grid->addWidget(customwidget1, 1,0);
    grid->addWidget(customwidget1, 1,1);
}
 
QCustomMainPage::resizeEvent(QResizeEvent *re ){
    emit sizeChange(re->size());
}

QCustomResizeWidget::QCustomResizeWidget(QWidget *parent):QFrame (parent){
    QLabel *label1 = new QLabel("label1");
    QLabel *label2 = new QLabel("label2");
    QVBoxLayout *clayout = new QVBoxLayout(this);
    clayout->addWidget(label1);
    clayout->addWidget(label2);
}

void QCustomResizeWidgetsize::ChangeSlot(QSize size){
    currentsize = QSize(size.width()/10, size.width()/10); // keep it square
    this->setFixedSize(currentsize);
}
QSize QCustomResizeWidgetsize::sizeHint(void) const{
    return this->currentsize;
}
QSize minimumSizeHint(void) const{
    // return this->currentsize;
    return QSize(1,1); // allow widget to resize down to 1,1 (to get this partially working)
}

QCustomMainPage::QCustomMainPage(QWidget *parent) : QWidget(parent){
    QCustomResizeWidget *customwidget1 = new QCustomResizeWidget;
      connect(this, SIGNAL(sizeChange(QSize)), customwidget1, SLOT(ChangeSlot(QSize)));
    QCustomResizeWidget *customwidget2 = new QCustomResizeWidget;
      connect(this, SIGNAL(sizeChange(QSize)), customwidget1, SLOT(ChangeSlot(QSize)));
    QCustomResizeWidget *customwidget3 = new QCustomResizeWidget;
      connect(this, SIGNAL(sizeChange(QSize)), customwidget1, SLOT(ChangeSlot(QSize)));
    QCustomResizeWidget *customwidget4 = new QCustomResizeWidget;
      connect(this, SIGNAL(sizeChange(QSize)), customwidget1, SLOT(ChangeSlot(QSize)));

    QGridLayout *grid = new QGridLayout(this);
    grid->addWidget(customwidget1, 0,0);
    grid->addWidget(customwidget1, 0,1);
    grid->addWidget(customwidget1, 1,0);
    grid->addWidget(customwidget1, 1,1);
}

QCustomMainPage::resizeEvent(QResizeEvent *re ){
    emit sizeChange(re->size());
}

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