【C++】【Qt】Qt事件监听器

Qt除了使用信号槽机制来监听事件，还可以像其它语言或UI框架一样，使用回调式的事件监听

	//qeventfilter.h
	
	#ifndef QEVENTFILTER_H
	#define QEVENTFILTER_H
	
	#include "qlib.h"
	
	class QEventFilter : public QObject {
	    Q_OBJECT
	
	  public:
	    QEventFilter(QObject *parent = nullptr);
	
	    bool event(QEvent *event);
	
	    bool eventFilter(QObject *target, QEvent *event);
	};
	
	#endif

	//qeventfilter.cpp
	
	#include "qeventfilter.h"
	
	QEventFilter::QEventFilter(QObject *parent) : QObject(parent) {}
	
	bool QEventFilter::event(QEvent *event) {
	    return false;
	}
	
	bool QEventFilter::eventFilter(QObject *target, QEvent *event) {
	    if (event->type() == QMouseEvent::MouseButtonRelease)
	        std::cout