Drawing QLineF objects from centre of QGraphicsScene. Keep start of both as origin

coffee-bean

Hi all,

This is more of a 'how do I do this' than anything else. Basically, I'd like to draw two lines from the centre of a graphics scene, but keep the centre of the QGrahpicsScene as the origin, without the centre of the two lines moving (better described here https://www.youtube.com/watch?v=b35JF4LqtBs at 6:20) making the centre of the two lines the origin. What I would like is the start X,Y of the two lines (where they meet) to be fixed the the centre of the QGraphicsView.

Here's my code:

dialog.h
@
#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include <QtCore>
#include <QtGui>
#include <QGraphicsScene>
#include <QGraphicsItem>
#include <QLineF>

namespace Ui {
class Dialog;
}

class Dialog : public QDialog
{
Q_OBJECT

public:
explicit Dialog(QWidget *parent = 0);
~Dialog();

private:
Ui::Dialog *ui;
QGraphicsScene *scene;
QLineF angleLine1;
QLineF angleLine2;
QPointF centre;

};

#endif // DIALOG_H
@

dialog.cpp
@
#include "dialog.h"
#include "ui_dialog.h"

Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
{
ui->setupUi(this);

//Create the scene
scene = new QGraphicsScene(this);
//send it to the graphics view
ui->graphicsView->setScene(scene);


QPen blackPen(Qt::black);
QPen redPen(Qt::red);
redPen.setWidth(3);
blackPen.setWidth(3);

//get centre coordinates
int centX, centY;
centX = ( (ui->graphicsView->width()) / 2);
centY = ( (ui->graphicsView->height()) / 2);

//QPoint object for centre of graphics widget
centre = QPointF(centX, centY);

//set the start as the centre point etc
angleLine1.setP1(centre);
angleLine1.setAngle(45);
angleLine1.setLength(100);
scene->addLine(angleLine1, blackPen);

angleLine2.setP1(centre);
angleLine2.setAngle(-5);
angleLine2.setLength(150);
scene->addLine(angleLine2, redPen);

}

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

@

angleLine1 and angleLine2 meet at the origin (centre of QGraphicsView), then move, making the centre of both lines at the origin

!http://i1380.photobucket.com/albums/ah174/omarplymomarplym/ScreenShot2014-11-14at214132_zps414d21e4.png(QGraphicsScene)!

What I'd like is where line1 and line2 start to stay at the centre of the QGraphicsScene, any idea how to do this?

Many thanks
Omar :)