MainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
protected:
    bool eventFilter(QObject *watched, QEvent *event);

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H
 

MainWindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->label->installEventFilter(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}


bool MainWindow::eventFilter(QObject *watched, QEvent *event)
{
    if(watched == ui->label)
    {
        if(event->type() == QEvent::MouseButtonPress)
        {
            qDebug()<<"label clicked!";
        }
    }
    return QMainWindow::eventFilter(watched,event);
}