I m trying to make a simple draggable item using the graphics framework. Here s the code for what I did so far:

Widget class:

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = 0);
    ~Widget();

};

Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
    DragScene *scene = new DragScene();
    DragView *view = new DragView();
    QHBoxLayout *layout = new QHBoxLayout();

    DragItem *item = new DragItem();
    view->setAcceptDrops(true);
    scene->addItem(item);
    view->setScene(scene);
    layout->addWidget(view);
    this->setLayout(layout);

}

Widget::~Widget()
{
}

DragView class:

class DragView : public QGraphicsView
{
public:
    DragView(QWidget *parent = 0);
};

DragView::DragView(QWidget *parent) : QGraphicsView(parent)
{
    setRenderHints(QPainter::Antialiasing);
}

DragScene class:

class DragScene : public QGraphicsScene
{
public:
    DragScene(QObject* parent = 0);

protected:
    void dragEnterEvent(QGraphicsSceneDragDropEvent *event);
    void dragMoveEvent(QGraphicsSceneDragDropEvent *event);
    void dragLeaveEvent(QGraphicsSceneDragDropEvent *event);
    void dropEvent(QGraphicsSceneDragDropEvent *event);
};

DragScene::DragScene(QObject* parent) : QGraphicsScene(parent)
{
}

void DragScene::dragEnterEvent(QGraphicsSceneDragDropEvent *event){
}

void DragScene::dragMoveEvent(QGraphicsSceneDragDropEvent *event){
}

void DragScene::dragLeaveEvent(QGraphicsSceneDragDropEvent *event){
}

void DragScene::dropEvent(QGraphicsSceneDragDropEvent *event){
    qDebug() << event->pos();
    event->acceptProposedAction();
    DragItem *item = new DragItem();
    this->addItem(item);
    // item->setPos(event->pos()); before badgerr s tip
    item->setPos(event->scenePos());
}

DragItem class:

class DragItem : public QGraphicsItem
{
public:
    DragItem(QGraphicsItem *parent = 0);
    QRectF boundingRect() const;
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0);

protected:
    void mouseDoubleClickEvent(QGraphicsSceneMouseEvent *event);
    void mouseMoveEvent(QGraphicsSceneMouseEvent *event);
    void mousePressEvent(QGraphicsSceneMouseEvent *event);
    void mouseReleaseEvent(QGraphicsSceneMouseEvent *event);
};

DragItem::DragItem(QGraphicsItem *parent) : QGraphicsItem(parent)
{
    setFlag(QGraphicsItem::ItemIsMovable);
}

QRectF DragItem::boundingRect() const{
    const QPointF *p0 = new QPointF(-10,-10);
    const QPointF *p1 = new QPointF(10,10);
    return QRectF(*p0,*p1);
}

void DragItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget){
    if(painter == 0)
        painter = new QPainter();
    painter->drawEllipse(QPoint(0,0),10,10);
}

void DragItem::mouseDoubleClickEvent(QGraphicsSceneMouseEvent *event){

}

void DragItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event){
}

void DragItem::mousePressEvent(QGraphicsSceneMouseEvent *event){
    QMimeData* mime = new QMimeData();
    QDrag* drag = new QDrag(event->widget());
    drag->setMimeData(mime);
    drag->exec();
}

void DragItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *event){
}

main.cpp instantiates a Widget and shows it. When I try to drag the circle, the app just creates another circle over the original one, regardless of where I release the drag. qDebug() in DragScene s dropEvent() shows QPointF(0,0) everytime the drag ends. I m having a hard time trying to understand exactly what I have to do, which classes I should subclass, which methods needs to be overriden, to make this work. The documentation on this isn t very detailed. I d like to know how to make this work, and if there s some other, more comprehensive resource to learn about the graphics view framework, besides the official documentation (which is excellent btw, but it would be great if there was a more detailed treatise on the subject).

EDIT:

Following badgerr s advice, I replaced item->pos() in DragScene::dropEvent() with item->scenePos(), now the drop event creates a new circle in the drop site, which is more or less what I wanted. But the original circle is still in place, and while the drag is in progress, the item doesn t follow the mouse cursor.

The QGraphicsSceneDragDropEvent documentation says that pos() should return the cursor position in relation to the view that sent the event, which, unless I got it wrong, shouldn t be (0,0) all the time. Weird.

I ve read in a forum post that you can use QDrag::setPixMap() to show something during the drag, and in examples I ve seen pictures being set as pixmaps, but how do I make the pixmap just like the graphics item I m supposed to be dragging?