Subclassing QTreeWidgetItem for Drag & Drop?

[kerchen]

Greetings all,
Regular lurker, first time posting. I want to be able to allow drops only on certain items in a QTreeWidget. Is it possible to subclass QTreeWidgetItem to allow it to be a "drop target" for a drag & drop operation? The code below shows the approach I tried, but it doesn't work correctly: only the first MyTreeWidgetItem I add to the tree control accepts drops! The fact that this only 'sort of' works makes me suspect I'm bumping into a side effect of some of Qt's C++ magic. Is it possible to subclass QTreeWidgetItem to accept drops? Alternatively, if there is another way to achieve the goal of fine-grained control of which items can be "dropped on", I'd be happy to learn about that.

Thanks!
Paul Kerchen

Platform/environment: Qt 4.3.3, MSVC 7.1, Windows XP

class MyTreeWidgetItem : public QWidget, public QTreeWidgetItem
{
    Q_OBJECT
 
public:
    MyTreeWidgetItem( QTreeWidget* parent);
 
signals:
    void itemDropped( MyTreeWidgetItem* item, QWidget* source );
 
protected:
    void dragEnterEvent(QDragEnterEvent* event);
    void dragMoveEvent(QDragMoveEvent* event);
    void dropEvent(QDropEvent* event);
};
 
MyTreeWidgetItem::MyTreeWidgetItem( TreeWidget* parent )
: QWidget(parent)
, QTreeWidgetItem( parent )
{
    setAcceptDrops(true);
}
 
 
 
void MyTreeWidgetItem::
dragEnterEvent(QDragEnterEvent* event)
{
    event->setDropAction(Qt::CopyAction);
    event->acceptProposedAction();
}
 
 
void MyTreeWidgetItem::
dragMoveEvent(QDragMoveEvent* event)
{
    event->setDropAction(Qt::CopyAction);
    event->acceptProposedAction();
}
 
 
void MyTreeWidgetItem::
dropEvent(QDropEvent* event)
{
    event->setDropAction(Qt::CopyAction);
    event->acceptProposedAction();
    emit itemDropped(this, event->source());
}

class MyTreeWidgetItem : public QWidget, public QTreeWidgetItem
{
    Q_OBJECT

public:
    MyTreeWidgetItem( QTreeWidget* parent);

signals:
    void itemDropped( MyTreeWidgetItem* item, QWidget* source );

protected:
    void dragEnterEvent(QDragEnterEvent* event);
    void dragMoveEvent(QDragMoveEvent* event);
    void dropEvent(QDropEvent* event);
};

MyTreeWidgetItem::MyTreeWidgetItem( TreeWidget* parent )
: QWidget(parent)
, QTreeWidgetItem( parent )
{
    setAcceptDrops(true);
}



void MyTreeWidgetItem::
dragEnterEvent(QDragEnterEvent* event)
{
    event->setDropAction(Qt::CopyAction);
    event->acceptProposedAction();
}


void MyTreeWidgetItem::
dragMoveEvent(QDragMoveEvent* event)
{
    event->setDropAction(Qt::CopyAction);
    event->acceptProposedAction();
}


void MyTreeWidgetItem::
dropEvent(QDropEvent* event)
{
    event->setDropAction(Qt::CopyAction);
    event->acceptProposedAction();
    emit itemDropped(this, event->source());
}

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