A problem with drag and drop progressbar

[fouffa89]

I wish that my progressbar can be moved without creating a new one , the problem with this code is that it create a new progressbar when mouse click is released. Please help me.
@
void DropWidget::dropEvent(QDropEvent *event)
{

if (event->mimeData()->hasFormat("application/x-dnditemdata")) {
    QPoint offset;
      QProgressBar *p=new QProgressBar(this);
        p->move(event->pos() - offset);
        p->setValue(70);
        p->setFixedWidth(200);
        p->show();
        p->setAttribute(Qt::WA_DeleteOnClose);
        p->setAcceptDrops(true);
        p->setFocusPolicy(Qt::StrongFocus);
       

    if (event->source() == this) {
        event->setDropAction(Qt::MoveAction);
        event->accept();
    } else {
        event->acceptProposedAction();
    }
} else {
    event->ignore();
}

}

//! [1]
void DropWidget::mousePressEvent(QMouseEvent *event)
{
QProgressBar child = static_cast<QProgressBar>(childAt(event->pos()));
if (!child)
return;
QByteArray itemData;
QDataStream dataStream(&itemData, QIODevice::WriteOnly);
dataStream << child << QPoint(event->pos() - child->pos());

//! [1]

//! [2]
QMimeData *mimeData = new QMimeData;
mimeData->setData("application/x-dnditemdata", itemData);
//! [2]

//! [3]
QDrag *drag = new QDrag(this);
drag->setMimeData(mimeData);
drag->setHotSpot(event->pos() - child->pos());
//! [3]
if (!drag->exec(Qt::CopyAction | Qt::MoveAction, Qt::CopyAction) == Qt::MoveAction) {
child->close();
} else{
child->show();
}
}
@

[b1gsnak3]

Well... Couldn't you just use one global QProgressBar? Instead of creating a child in mousePressEvent you could just check to see if the event->pos() corresponds with the progressbars pos...

[fouffa89]

sorry but I don't have just one progressbar so I need another solution.

[Sam]

In your implementation you are starting your drag on mousePressEvent() , so everytime when mousePressEvent is returned your dropEvent() is called which in turn creates a new QProgressBar at line 6.

You need to implement you QDrag in a new function startDrag() and inside mouseMoveEvent() you can check for the minimum distance and then call startDrag() function.

For eg

@void DropWidget::mouseMoveEvent(QMouseEvent *event)
{

....
....

// dragPoint = event->pos(); comes from mousePressEvent()
int distance = (event->pos()- dragPoint).manhattanLength();

if (distance >=QApplication::startDragDistance())
{
    startDrag(Qt::MoveAction);
}

}@

@void DropWidget::startDrag(Qt::DropActions supportedActions)
{

QProgressBar child = static_cast<QProgressBar>(childAt(event->pos()));
if (!child)
return;

QByteArray itemData;
QDataStream dataStream(&itemData, QIODevice::WriteOnly);

dataStream << child << QPoint(event->pos() - child->pos());

//! [1]
//! [2]

QMimeData *mimeData = new QMimeData;
mimeData->setData("application/x-dnditemdata", itemData);

//! [2]

//! [3]
QDrag *drag = new QDrag(this);
drag->setMimeData(mimeData);
drag->setHotSpot(event->pos() - child->pos());
//! [3]

if (!drag->exec(Qt::CopyAction | Qt::MoveAction, Qt::CopyAction) == Qt::MoveAction)

{
child->close();

} else
{
    child->show();
}

}@

[fouffa89]

I don't understand why distance is used in this code , my problem is that i can't move the progressbar , I always get a new copy

[Sam]

Well the above implementation is another way of doing it. The distance is a constraint that is used to start the drag only after the item is clicked and moved to a minimum distance, which in your case is not required.

In your implementation change line 49 from

@if (!drag->exec(Qt::CopyAction | Qt::MoveAction, Qt::CopyAction) == Qt::MoveAction) @

to

@if (drag->exec(Qt::CopyAction | Qt::MoveAction, Qt::CopyAction) == Qt::MoveAction) @