拖动QTreeview 的节点到其他的控件中

记录qt拖动树节点

1.设置Qtreeview的属性 dragEnabled  =true,    dragdropmode =dragonly  ,defaultdropaction = copyaction

2.设置接收qtreeview节点的控件setacceptdrops  =true  (各种控件可能不一样)

3.重写接收节点的控件的dragEnterEvent，dragLeaveEvent ，dragMoveEvent ，dropEvent

　注意：mimedata的format类型是"application/x-qabstractitemmodeldatalist"，这个类型可以通过QStandardItemModel的mimeTypes获得

void dragEnterEvent( QGraphicsSceneDragDropEvent *pEvent )
{
QGraphicsItem::dragEnterEvent(pEvent);

if(pEvent->mimeData()->hasFormat("application/x-qabstractitemmodeldatalist"))
{
qDebug("%s ",__FUNCTION__);
pEvent->acceptProposedAction();
}
}

void CGraphicsItemRectScreen::dropEvent( QGraphicsSceneDragDropEvent *pEvent )
{
QGraphicsItem::dragEnterEvent(pEvent);
QByteArray arr =pEvent->mimeData()->data("application/x-qabstractitemmodeldatalist");

QVector<int> rows, columns;//节点在QStandardItemModel中的行和列
QVector<QMap<int, QVariant> > data;//节点的基它的属性

QByteArray encoded;
QDataStream stream(&arr, QIODevice::ReadOnly);
int top = INT_MAX;
int left = INT_MAX;
int bottom = 0;
int right = 0;
while (!stream.atEnd()) {
int r, c;
QMap<int, QVariant> v;
stream >> r >> c >> v;
rows.append(r);
columns.append(c);
data.append(v);
top = qMin(r, top);
left = qMin(c, left);
bottom = qMax(r, bottom);
right = qMax(c, right);
}

emit sigDropEvent(this,rows.at(0),columns.at(0),data.at(0)[0].toString());

}

解释节点的mimedata可以看  qabstractitemmodel.cpp里边的方法decodeData，encodeData