Drag 'n Drop QListWidget: no text while dragging if not default drag used

I have a little problem with DnD using a QListWidget.
I have to create my own QListWidget class (called CListWidget) as I need to implement my own mousePressEvent method.

Code:

---

void CListWidget::mousePressEvent(QMouseEvent *event)
{
	QListWidget::mousePressEvent(event);
 
	if ( currentItem()->text().isEmpty() )
	{
		clearSelection();
		return;
	}
 
	QByteArray itemData;
	QDataStream dataStream(&itemData, QIODevice::WriteOnly);
	dataStream << currentItem()->text();
 
	QMimeData *mimeData = new QMimeData;
	mimeData->setData("application/x-dnditemdata", itemData);
	mimeData->setText(currentItem()->text());
 
	QDrag *drag = new QDrag(this);
	drag->setMimeData(mimeData);
	drag->exec(Qt::CopyAction);
}

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When using this code, I cannot see any text while dragging.
If I comment the code and just enable the drag:

Code:

---

CListWidget::CListWidget(QWidget* parent) : QListWidget(parent)
{
	setDragEnabled(true);
}

---

the text of the CListWidget item is shown while dragging.

Why ?

The problem is also that, if I use the QT default drag, I don't have any text in the item dragged.

Thanks for any suggestion :)


PS: Using Qt version 4.4.0 under Linux Ubuntu 8.04

You will need to set pixmap in mime data to see the text while dragging...
From the docs -

Code:

---

void QAbstractItemView::startDrag(Qt::DropActions supportedActions)
{
    Q_D(QAbstractItemView);
    QModelIndexList indexes = d->selectedDraggableIndexes();
    if (indexes.count() > 0) {
        QMimeData *data = d->model->mimeData(indexes);
        if (!data)
            return;
        QRect rect;
        QPixmap pixmap = d->renderToPixmap(indexes, &rect);         // HERE THEY RENDER TEXT TO PIXMAP
        rect.adjust(horizontalOffset(), verticalOffset(), 0, 0);
        QDrag *drag = new QDrag(this);
        drag->setPixmap(pixmap);      // THE PIXMAP FOR SHOWING TEXT
        drag->setMimeData(data);
        drag->setHotSpot(d->pressedPosition - rect.topLeft());
        Qt::DropAction defaultDropAction = Qt::IgnoreAction;
        if (d->defaultDropAction != Qt::IgnoreAction && (supportedActions & d->defaultDropAction))
            defaultDropAction = d->defaultDropAction;
        else if (supportedActions & Qt::CopyAction && dragDropMode() != QAbstractItemView::InternalMove)
            defaultDropAction = Qt::CopyAction;
        if (drag->exec(supportedActions, defaultDropAction) == Qt::MoveAction)
            d->clearOrRemove();
    }
}

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Thanks but I don't follow you...
I guess I have to reimplement the virtual method startDrag in my CListWidget class, but I get errors.

Well, I've solved in this way:

added the following to the constructor:

Code:

---

QPen   pen(QColor("blue"));
	m_Pixmap = new QPixmap(QSize(180, 20));
	m_Painter = new QPainter(m_Pixmap);
	m_Painter->setPen(pen);

---

and the mousePressEvent is now:

Code:

---

void CListWidget::mousePressEvent(QMouseEvent *event)
{
	QListWidget::mousePressEvent(event);
 
	if ( currentItem()->text().isEmpty() )
	{
		clearSelection();
		return;
	}
 
	QByteArray itemData;
	QDataStream dataStream(&itemData, QIODevice::WriteOnly);
	dataStream << currentItem()->text();
 
	m_Painter->fillRect(QRect(0, 0, 180, 20), QBrush(QColor("orange"))); // ADDED
	m_Painter->drawText(QRect(10, 0, 170, 20), currentItem()->text() );  // ADDED
 
	QMimeData *mimeData = new QMimeData;
	mimeData->setData("application/x-dnditemdata", itemData);
	mimeData->setText(currentItem()->text());
 
	QDrag *drag = new QDrag(this);
	drag->setPixmap(*m_Pixmap);   // ADDED
	drag->setMimeData(mimeData);
	drag->exec(Qt::CopyAction);
}

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