Line doesnt Rotate on its center

[21altf]

I'm tryin to make a QGraphicsLineItem rotate, but everytime i trigger rotate it moves to another location. I mean, it does rotate, but not in a especific point! I think it its rotation in its QGraphicsView central point. I dunno how to fix it.

Here is the code:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <Qt>
#include <QGS.h>
#include <QGraphicsScene>
#include <QGraphicsLineItem>
#include <QEvent>
#include <QDropEvent>
#include <QSignalMapper>
#include <QMouseEvent>
#include <QtDebug>
#include <QWidget>
#include <QList>
#include <math.h>
#include <QtCore/qmath.h>
 
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
   ui->setupUi(this);
    MainWindow::setCentralWidget(ui->view);
    scene = new QGS(this);
    scene->setSceneRect(MainWindow::geometry());
    ui->view->setSceneRect(MainWindow::geometry());
 
    QObject::connect(ui->action_Line,SIGNAL(triggered()),this,SLOT(criarLinha()));
    QObject::connect(ui->action_New,SIGNAL(triggered()),this,SLOT(newFile()));
    QObject::connect(ui->actionR_otate,SIGNAL(triggered()),this,SLOT(rotate()));
 
    ui->view->setScene(scene);
    ui->view->setMouseTracking(true);
    setWindowTitle(tr("AutoPac v1.0"));
 
 
 
}
 
//Private Functions
MainWindow::~MainWindow()
{
    delete ui;
}
 
 
//Private Slots
void MainWindow::criarLinha()
{
 
    scene->setMode(scene->InsertLine);
}
 
void MainWindow::newFile()
{
  scene = new QGS(this);
  scene->setSceneRect(QRectF(0, 0, 512, 600));
  ui->view->setScene(scene);
}
 
void MainWindow::rotate()
{
    int i = 0;
//    qreal x1,y1,x2,y2;
 
//    x1 = 0;
//    y1 = 0;
//    x2 = 0;
//    y2 = 0;
 
//    double pi = 3.1415;
 
    for (i = 0 ; i < scene->selectedItems().length() ; i++)
    {
        if(scene->selectedItems().at(i)->type() == QGraphicsLineItem::Type)
        {
 
            scene->selectedItems().at(i)->rotate(90); //90 is just an example
            scene->selectedItems().at(i)->setSelected(true);
 
 
            }
    }
 
}

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <Qt>
#include <QGS.h>
#include <QGraphicsScene>
#include <QGraphicsLineItem>
#include <QEvent>
#include <QDropEvent>
#include <QSignalMapper>
#include <QMouseEvent>
#include <QtDebug>
#include <QWidget>
#include <QList>
#include <math.h>
#include <QtCore/qmath.h>


MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
   ui->setupUi(this);
    MainWindow::setCentralWidget(ui->view);
    scene = new QGS(this);
    scene->setSceneRect(MainWindow::geometry());
    ui->view->setSceneRect(MainWindow::geometry());

    QObject::connect(ui->action_Line,SIGNAL(triggered()),this,SLOT(criarLinha()));
    QObject::connect(ui->action_New,SIGNAL(triggered()),this,SLOT(newFile()));
    QObject::connect(ui->actionR_otate,SIGNAL(triggered()),this,SLOT(rotate()));

    ui->view->setScene(scene);
    ui->view->setMouseTracking(true);
    setWindowTitle(tr("AutoPac v1.0"));



}

//Private Functions
MainWindow::~MainWindow()
{
    delete ui;
}


//Private Slots
void MainWindow::criarLinha()
{

    scene->setMode(scene->InsertLine);
}

void MainWindow::newFile()
{
  scene = new QGS(this);
  scene->setSceneRect(QRectF(0, 0, 512, 600));
  ui->view->setScene(scene);
}

void MainWindow::rotate()
{
    int i = 0;
//    qreal x1,y1,x2,y2;

//    x1 = 0;
//    y1 = 0;
//    x2 = 0;
//    y2 = 0;

//    double pi = 3.1415;

    for (i = 0 ; i < scene->selectedItems().length() ; i++)
    {
        if(scene->selectedItems().at(i)->type() == QGraphicsLineItem::Type)
        {

            scene->selectedItems().at(i)->rotate(90); //90 is just an example
            scene->selectedItems().at(i)->setSelected(true);


            }
    }

}

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[Santosh Reddy]

Check this out, use setTransformOriginPoint(), and setRotation()

//main.cpp
#include <QtGui>
// QGraphicsLineItem rotate
class MyWidget : public QMainWindow
{
    Q_OBJECT
public:
    MyWidget(QWidget* parent = 0)
        : QMainWindow(parent)
        , scene(new QGraphicsScene(this))
        , view(new QGraphicsView(scene, this))
        , action_New(menuBar()->addAction("New", this, SLOT(newLine())))
        , action_Rotate(menuBar()->addAction("Rotate", this, SLOT(rotateLine())))
    {
        setCentralWidget(view);
        startTimer(100);
    }
private slots:
    void newLine()
    {
        QGraphicsLineItem* item = scene->addLine(0, 0, 100, 100, QPen(QBrush(Qt::red), 4));
        item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsMovable);
        item->setTransformOriginPoint(item->boundingRect().center());
    }
 
 
    void rotateLine()
    {
        for(int i = 0 ;i < scene->selectedItems().count() ;i++)
            if(scene->selectedItems().at(i)->isSelected())
                if(scene->selectedItems().at(i)->type() == QGraphicsLineItem::Type)
                    scene->selectedItems().at(i)->setRotation(scene->selectedItems().at(i)->rotation() + 20);
    }
protected:
    void timerEvent(QTimerEvent* event)
    {
        rotateLine();
    }
 
 
private:
    QGraphicsScene* scene;
    QGraphicsView*  view;
    QAction* action_New;
    QAction* action_Rotate;
};
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MyWidget w;
    w.show();
    return a.exec();
}
#include "main.moc"

//main.cpp
#include <QtGui>
// QGraphicsLineItem rotate
class MyWidget : public QMainWindow
{
    Q_OBJECT
public:
    MyWidget(QWidget* parent = 0)
        : QMainWindow(parent)
        , scene(new QGraphicsScene(this))
        , view(new QGraphicsView(scene, this))
        , action_New(menuBar()->addAction("New", this, SLOT(newLine())))
        , action_Rotate(menuBar()->addAction("Rotate", this, SLOT(rotateLine())))
    {
        setCentralWidget(view);
        startTimer(100);
    }
private slots:
    void newLine()
    {
        QGraphicsLineItem* item = scene->addLine(0, 0, 100, 100, QPen(QBrush(Qt::red), 4));
        item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsMovable);
        item->setTransformOriginPoint(item->boundingRect().center());
    }


    void rotateLine()
    {
        for(int i = 0 ;i < scene->selectedItems().count() ;i++)
            if(scene->selectedItems().at(i)->isSelected())
                if(scene->selectedItems().at(i)->type() == QGraphicsLineItem::Type)
                    scene->selectedItems().at(i)->setRotation(scene->selectedItems().at(i)->rotation() + 20);
    }
protected:
    void timerEvent(QTimerEvent* event)
    {
        rotateLine();
    }


private:
    QGraphicsScene* scene;
    QGraphicsView*  view;
    QAction* action_New;
    QAction* action_Rotate;
};
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MyWidget w;
    w.show();
    return a.exec();
}
#include "main.moc"

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