Class that inherits QWidget to create container of QPushbuttons - doing it correctly?

[ShamusVW]

I have created a class that I am calling from another class that deals with the user interface for my program.
The called class sets up a scrollable area that contains 2 QPushbuttons at this point to test it, and it works fine, however I am uneasy that what I have done is not quite correct, and I was wondering if someone could give me feedback on if it is correct, and how to improve it.
At this point I have made the 2 buttons very large (in height) only so that I can see that the effect of the scrolling action is working, which it is.
My concern is that I get the feeling that within the class, I am creating a widget again, even though it inherits a QWidget already, and so this shouldn't be needed.
Note that my code is based on code that I found online, and modified.

#include "stoppagereasons.h"
 
#include <QPushButton>
#include <QGridLayout>
#include <QScrollBar>
#include <QVBoxLayout>
#include <QScrollArea>
 
StoppageReasons::StoppageReasons(QWidget *parent)
    : QWidget(parent)
{
    QWidget *widget = new QWidget;
    QVBoxLayout *layout = new QVBoxLayout();
    QPushButton *btn = new QPushButton("test");
    btn->setFixedSize(100,500);
    QPushButton *btn2 = new QPushButton("test2");
    btn2->setFixedSize(100,500);
 
    layout->addWidget(btn);
    layout->addWidget(btn2);
    widget->setLayout(layout);
 
    QScrollArea *scroll = new QScrollArea;
    scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    scroll->setWidgetResizable(false);
    scroll->setWidget(widget);
 
    QVBoxLayout *vLayout = new QVBoxLayout();
    vLayout->addWidget(scroll);
    setLayout(vLayout);
}

#include "stoppagereasons.h"

#include <QPushButton>
#include <QGridLayout>
#include <QScrollBar>
#include <QVBoxLayout>
#include <QScrollArea>

StoppageReasons::StoppageReasons(QWidget *parent)
    : QWidget(parent)
{
    QWidget *widget = new QWidget;
    QVBoxLayout *layout = new QVBoxLayout();
    QPushButton *btn = new QPushButton("test");
    btn->setFixedSize(100,500);
    QPushButton *btn2 = new QPushButton("test2");
    btn2->setFixedSize(100,500);

    layout->addWidget(btn);
    layout->addWidget(btn2);
    widget->setLayout(layout);

    QScrollArea *scroll = new QScrollArea;
    scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    scroll->setWidgetResizable(false);
    scroll->setWidget(widget);

    QVBoxLayout *vLayout = new QVBoxLayout();
    vLayout->addWidget(scroll);
    setLayout(vLayout);
}

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[anda_skoa]

That looks ok.

Your widget contains a QScrollArea and it needs a widget as its content.

The only thing you could change is to make your widget a subclass of QScrollArea instead of having a single QScrollArea child

Cheers,
_

[ShamusVW]

Thanks anda_skoa

Would you mind giving me some code? I don't know how to do that.

[anda_skoa]

I am afraid I don't understand.

You obviously know how to create a subclass, so instead of deriving from QWidget you just derive from QScrollArea.

Cheers,
_

[ShamusVW]

Sorry, I didn't understand you correctly, so this is what I have done now.
Is this an improvement over the original code? Any other improvements I could do?
The code is definitely shorter, so I like that.

StoppageReasons::StoppageReasons(QScrollArea *parent)
    : QScrollArea(parent)
{
    QPushButton *btn = new QPushButton("test");
    btn->setFixedSize(400,350);
    QPushButton *btn2 = new QPushButton("test2");
    btn2->setFixedSize(400,350);
    QPushButton *btn3 = new QPushButton("test3");
    btn3->setFixedSize(400,350);
 
    QVBoxLayout *layout = new QVBoxLayout();
    layout->addWidget(btn);
    layout->addWidget(btn2);
    layout->addWidget(btn3);
 
    QWidget *widget = new QWidget;
    widget->setLayout(layout);
 
    setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    setWidgetResizable(false);
    setWidget(widget);
}

StoppageReasons::StoppageReasons(QScrollArea *parent)
    : QScrollArea(parent)
{
    QPushButton *btn = new QPushButton("test");
    btn->setFixedSize(400,350);
    QPushButton *btn2 = new QPushButton("test2");
    btn2->setFixedSize(400,350);
    QPushButton *btn3 = new QPushButton("test3");
    btn3->setFixedSize(400,350);

    QVBoxLayout *layout = new QVBoxLayout();
    layout->addWidget(btn);
    layout->addWidget(btn2);
    layout->addWidget(btn3);

    QWidget *widget = new QWidget;
    widget->setLayout(layout);

    setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    setWidgetResizable(false);
    setWidget(widget);
}

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[anda_skoa]

Yes, that's what I meant.

Looks good to me, the rest is a matter of personal preference.

E.g. I would first create the "widget" object, then its layout and then add the children as I go along.

Cheers,
_

[ShamusVW]

Thanks anda_skoa, I appreciate your input.