QApplication的消息重載

一、定義一個c++類：MyApplication

MyApplication.h

#ifndef MYAPPLICATION_H
#define MYAPPLICATION_H
#include <QApplication>

class MyApplication:public QApplication
{
public:
    MyApplication(int argc, char*argv[]):QApplication(argc, argv)
    {

    }
    bool notify(QObject *, QEvent *);
};

#endif // MYAPPLICATION_H

MyApplication.cpp

#include "myapplication.h"
#include <QApplication>
#include <QEvent>

#include <QDebug>
bool MyApplication::notify(QObject *object, QEvent *event){
    if(this->topLevelWidgets().count()>0)
       {
           QWidget* mainWnd = this->topLevelWidgets().at(0);
           if(object==(QObject*)mainWnd && event->type() == QEvent::Move)
           {
               // do ...
               qDebug() << "mainwnd is clicked";
           }
       }
    return QApplication::notify(object, event);
}

 

main.cpp

#include "widget.h"
#include "myapplication.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    MyApplication a(argc, argv);
    Widget w;
    w.show();

    return a.exec();
}