notify事件发送的机制

子类化QApplication在主函数中使用自己子类化的类建立事件循环。那么在自己子类化的QApplication中重新实现notify为什么打印两次内容。

myQApplication.c

#include "myqapplication.h"
#include <QDebug>

myQApplication::myQApplication(int &argc, char **argv):
    QApplication(argc, argv)
{

}


bool myQApplication::notify(QObject *obj, QEvent *e)
{
    if(e->type() == QEvent::KeyPress)
    {
        qDebug()<<"myQApplication KeyPress event";
    }

    return QApplication::notify(obj, e);
}

myQApplication.h

#ifndef MYQAPPLICATION_H
#define MYQAPPLICATION_H
#include <QApplication>


class myQApplication : public QApplication
{
public:
    myQApplication(int &argc, char **argv);
public:
    bool notify(QObject *, QEvent *);
};

#endif // MYQAPPLICATION_H

main.c

#include "widget.h"
#include "myqapplication.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    myQApplication a(argc, argv);

    Widget w;

    w.show();
    return a.exec();
}

但是打印的时候连续打印了两次。这是为什么呢？

https://blog.csdn.net/u014770862/article/details/72917061?utm_source=blogxgwz1