Qt之进入和出去和关闭事件

widget.h:

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include<QEvent>
class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = 0);
    ~Widget();
    void enterEvent(QEvent *e);
    void leaveEvent(QEvent *e);
    void closeEvent(QEvent *e);
};

#endif // WIDGET_H

widget.cpp:

#include "widget.h"
#include<QPalette>
Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
}
void Widget::enterEvent(QEvent *e)
{
    QPalette s=this->palette();
    s.setColor(QPalette::Background,Qt::red);
    this->setPalette(s);
}
void Widget::leaveEvent(QEvent *e)
{
    QPalette s=this->palette();
    s.setColor(QPalette::Background,Qt::green);
    this->setPalette(s);
}
void Widget:: closeEvent(QEvent *e)
{
    e->ignore();// 这样子就关不掉了
}
Widget::~Widget()
{

}

main.cpp:

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

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

    return a.exec();
}