Qt重新实现功能

Question

I need to subclass qt class and reimplement the virtual function. Say that i have the QLCDNumber class and I want to reimplement the function that set the position of the number when resize the LCD number screen, how to achieve that?

I read that by inhert a class from QLCDNumber and reimplement the function, but where to get that function code so that I can edit what needed in that function? I read the documentation but it explains the function uses and not show its code. Example image:

I mentioned the QLCDNumber class as example, I need to know the prosses of reimplemnt a virtual Qt class function.

Answer 1

For this particular problem you can use this type of approach where you can create an object which inherits QWidget and implement the paintEvent() of the class like this:

class MyWidget : public QWidget
{
    Q_OBJECT
public:
    explicit MyWidget(QWidget *parent = 0);
    ~MyWidget();
protected:
    void paintEvent(QPaintEvent *pe);
signals:
public slots:
};

and in the paintEvent()

void MyWidget::paintEvent(QPaintEvent *pe)
{
    QPainter *painter = new QPainter(this);
    painter->begin(this);
    // draw what you want here using painter
    // and consider your different layouts
    painter->end();
}