Не обновляется координата фигуры

#ifndef DIALOG_H
#define DIALOG_H
 
#include <QDialog>
#include "piewidget.h"
 
namespace Ui {
class Dialog;
}
 
 
class Dialog : public QDialog
{
    Q_OBJECT
 
public:
    explicit Dialog(QWidget *parent = 0);
    ~Dialog();
 
private slots:
    void on_pushButton_clicked();
 
private:
    Ui::Dialog *ui;
    PieWidget *newPie;
};
 
#endif // DIALOG_H

#ifndef PIEWIDGET_H
#define PIEWIDGET_H
 
#include <QWidget>
 
class PieWidget : public QWidget
{
    Q_OBJECT
public:
    explicit PieWidget(QWidget *parent = 0);
    ~PieWidget();
 
protected:
    void paintEvent(QPaintEvent *);
 
signals:
 
public slots:
    void updateImage();
 
private:
    double angle;
    int R;
    int figureSize;
    int x0;
    int y0;
};
 
#endif // PIEWIDGET_H

#include "dialog.h"
#include "ui_dialog.h"
 
 
Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
    newPie = new PieWidget;
}
 
Dialog::~Dialog()
{
    delete ui;
    delete newPie;
}
 
void Dialog::on_pushButton_clicked()
{
    newPie->updateImage();
}

#include "piewidget.h"
#include <QPainter>
#include <QTimer>
#include <cmath>
#include <QDebug>
 
PieWidget::PieWidget(QWidget *parent) : QWidget(parent)
{
    angle = 0;
    x0 = y0 = R = 50;
    figureSize = 40;
}
 
PieWidget::~PieWidget()
{
    qDebug() << "Destructor has been invoked";
}
 
void PieWidget::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setPen(Qt::DotLine);
    painter.drawEllipse(figureSize/2,figureSize/4,2*R,2*R);
 
    QRectF pieSize= QRectF(x0+sin(angle)*R, y0+cos(angle)*R, figureSize, figureSize);
    painter.setBrush(Qt::gray);
    painter.setPen(Qt::SolidLine);
    painter.drawPie(pieSize, 0, 180*16);
}
 
void PieWidget::updateImage(){
    if(angle<3.14){
        angle+=3.14/180;
        qDebug() << angle;
        update();
        QTimer::singleShot(50,this,SLOT(updateImage()));
    }
}