Qt5贪吃蛇窗口界面有关问题，求解

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include  "snake.h"
#include <QTextCodec>


MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF8"));
    setWindowTitle(tr("贪吃蛇"));
    MenuBarSize=20;
    setFixedSize(510,510+MenuBarSize);
    dealMenu();
    IsDie=false;
    bRun=false;
    timer=new QTimer(this);
    connect(timer,SIGNAL(timeout()),this,SLOT(timeout1()));
    times=200;
    timer->start(times);
}

MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::timeout1()
{
    if(bRun==false)
    {
        timer->stop();
        return;
    }
    snake.Move();
    IsDie=snake.IsDie();
    if(IsDie)
    {
        timer->stop();
        bRun=false;
        QMessageBox::information(this,tr("游戏结束"),tr("太菜了！"));
        IsDie=false;
        snake.Clear();
        return;
    }
   update();
}
void MainWindow::paintEvent(QPaintEvent *event)
{
   QPainter painter(this);
   painter.setBrush(Qt::black);
   painter.drawRect(0, 0, size().width(), size().height());
   if (IsDie || !bRun)
   {
       return;
   }
   vector<Node> node;
   Node food;
   snake.OutputSnake(node, food);
   //画果子
   painter.setBrush(Qt::red);
   painter.drawEllipse(10*food.x, 10*food.y+MenuBarSize, 10, 10);
   //画墙
   painter.setBrush(Qt::white);
   painter.drawRect(0, 0+MenuBarSize, 510, 10);  //上
   painter.drawRect(0, 500+MenuBarSize, 510, 10); //下
   painter.drawRect(0, 0+MenuBarSize, 10, 510); //左
   painter.drawRect(500, 0+MenuBarSize, 10, 510); //右
   painter.setBrush(Qt::yellow);
   painter.drawRect(10*node[0].x, 10*node[0].y+MenuBarSize, 10, 10);
   //蛇身
   painter.setBrush(Qt::red);
   int n = node.size();
   for (int i = 1; i < n; i++)
   {
       painter.drawRect(10*node[i].x, 10*node[i].y+MenuBarSize, 9, 9);
   }
   node.clear();
   QWidget::paintEvent(event);
}
void MainWindow::keyPressEvent(QKeyEvent * event)
{
    int direct = 0;
    switch (event->key())
    {
       case Qt::Key_Up:
           direct = 1;
           break;
       case Qt::Key_Right:
           direct = 2;
           break;
       case Qt::Key_Down:
           direct = 3;
           break;
       case Qt::Key_Left:
           direct = 4;
           break;
       case Qt::Key_U:
           speedUp();
           break;
       case Qt::Key_D:
           speedDown();
           break;
       default:
           break;
    }
    snake.ChangeDirector(direct);
    QWidget::keyPressEvent(event);
   }

void MainWindow::dealMenu(void)
{
       QMenuBar * menuBar = new QMenuBar(this);