Рисование линии при нажатии лкм

#include <QApplication>
 
#include "paint.h"
int main( int argc, char** argv ){
    QApplication app( argc, argv );
 
    Paint paint;
    paint.show();
 
    return app.exec();
}

#ifndef PAINT_H
#define PAINT_H
 
#include <QWidget>
class Paint : public QWidget
{
    Q_OBJECT
public:
    Paint(QWidget *parent = 0);
    QWidget *wid;
 
protected:
    virtual void paintEvent(QPaintEvent *event);
 virtual void mousePressEvent(QMouseEvent *event);
};
 
#endif // PAINT_H

#include "paint.h"
 
#include <QtGui>
#include <QPainter>
#include <QMouseEvent>
//---------------------
Paint::Paint(QWidget *parent) :
    QWidget(parent)
{
    setPalette(QPalette(Qt::white));
    setWindowTitle( "Paint" );
    wid = new QWidget(this);
    wid->resize(400, 400);
    wid->move(30, 30);
    wid->setAutoFillBackground(false);
    update();
}
 
void Paint::paintEvent(QPaintEvent *event){
       QPainter painter ;
       painter.begin(this);
       QBrush brush(Qt::red, Qt::SolidPattern);
       painter.setBrush(brush);
       painter.drawLine(50, 50, 150, 150);
       painter.end();
}
void Paint::mousePressEvent(QMouseEvent *event){
if( !(Qt::LeftButton & event->button()) )
     return;
   QPainter painter ;
   painter.begin(this->wid);
   painter.setBrush(Qt::red);
   painter.drawLine(60, 60, event->x(), event->y());
   painter.end();
   update();
}

QPainter painter;