Draw QSpinBox on top of QPushButton

[stefanadelbert]

I would like to create a custom widget based on a QPushButton with a QSpinBox drawn inside it. Below is the class I currently have it:

class CQuantityPushButton : public QPushButton
{
    Q_OBJECT
 
    typedef QPushButton SuperClass;
 
public:
    CQuantityPushButton(const QString& label, QWidget *parent = 0) : SuperClass(parent)
    {
        spinBox = new QSpinBox(this);
        setText(label);
 
        connect(this, SIGNAL(clicked()), this, SLOT(Triggered()));
    }
    ~CQuantityPushButton() {}
 
signals:
    void triggered(int);
 
private slots:
    void
    Triggered(int)
    {
        emit triggered(spinBox->value());
    }
 
protected:
    void
    CQuantityPushButton::paintEvent(QPaintEvent *event)
    {
        SuperClass::paintEvent(event);
    }
 
private:
    QSpinBox* spinBox;
};

class CQuantityPushButton : public QPushButton
{
    Q_OBJECT

    typedef QPushButton SuperClass;

public:
    CQuantityPushButton(const QString& label, QWidget *parent = 0) : SuperClass(parent)
    {
        spinBox = new QSpinBox(this);
        setText(label);

        connect(this, SIGNAL(clicked()), this, SLOT(Triggered()));
    }
    ~CQuantityPushButton() {}

signals:
    void triggered(int);

private slots:
    void
    Triggered(int)
    {
        emit triggered(spinBox->value());
    }

protected:
    void
    CQuantityPushButton::paintEvent(QPaintEvent *event)
    {
        SuperClass::paintEvent(event);
    }

private:
    QSpinBox* spinBox;
};

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This image shows what I'm actually seeing when the class above is rendered and then it shows a Photoshopped example of what I would like to see.

QuantityButton.jpg

The way it's currently being drawn (the SpinBox floating above the PushButton) is exactly what I expected to see. But I would like to paint the Spinbox inside the PushButton to the left of the button text - I would like the SpinBox to be part of the PushButton contents.

Could anyone give me some tips? I'm guessing that I'll need to do some work in paintEvent, which is why I have an override in place (which just calls QPushButton::paintEvent for the moment).

For anyone reading this who want more info on Qt widget painting, this seems to be a good article.

Thanks
Stefan