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QT本是就支持鼠标左键选中拖动的功能，Drag和Drop。查看以下示例：

拖动功能包含两个窗口：一个是源窗口，一个是目标窗口。
在源窗口需要实现：

	void mousePressEvent(QMouseEvent *event) override;void mouseReleaseEvent(QMouseEvent *event) override;void mouseMoveEvent(QMouseEvent *event) override;

在目标窗口需要实现：

	//窗口进入拖动void dragEnterEvent(QDragEnterEvent *event) override;//拖动离开void dragLeaveEvent(QDragLeaveEvent *event) override;//拖动移动void dragMoveEvent(QDragMoveEvent *event) override;//拖动松开鼠标void dropEvent(QDropEvent *event) override;

具体实现过程：

//记录拖拽初始位置
void DragListView::mousePressEvent(QMouseEvent *event) {if (event->buttons() & Qt::LeftButton) {startPos = event->pos();_modelIndex = indexAt(event->pos());}
}void DragListView::mouseReleaseEvent(QMouseEvent *event) {if ((event->pos() - startPos).manhattanLength() > 5) {return;}QModelIndex index = indexAt(event->pos());setCurrentIndex(index);  //鼠标relesse时才选中
}void DragListView::mouseMoveEvent(QMouseEvent *event) {if (event->buttons() & Qt::LeftButton) {if ((event->pos() - startPos).manhattanLength() < QApplication::startDragDistance()) {return;}QModelIndex theDragIndex = indexAt(startPos);theDragRow = theDragIndex.row();setCurrentIndex(theDragIndex);  //拖拽即选中QStandardItemModel* slm = dynamic_cast<QStandardItemModel*>(model());QStandardItem *curItem = slm->itemFromIndex(_modelIndex);if (curItem == nullptr) {return;}_selectJBCode = curItem->data().toInt();//调用接口选中Item_iDragItemJB->dragItem(_modelIndex);//[1]把拖拽数据放在QMimeData容器中QString text = curItem->text();QIcon icon = curItem->icon();QIcon icon_hover = curItem->icon();QByteArray itemData;QDataStream dataStream(&itemData, QIODevice::WriteOnly);dataStream << _selectJBCode << text ;QMimeData *mimeData = new QMimeData;mimeData->setData(myMimeType(), itemData);//[2]设置拖拽时的缩略图Thumbnail *DragImage = new Thumbnail(this);DragImage->setupThumbnail(icon_hover, text);//DragImage->setIconSize(18);  //default:20QPixmap pixmap = DragImage->grab();QDrag *drag = new QDrag(this);drag->setMimeData(mimeData);drag->setPixmap(pixmap);drag->setHotSpot(QPoint(pixmap.width() / 2, pixmap.height() / 2));if (drag->exec(Qt::MoveAction) == Qt::MoveAction) {}}
}

目标窗口实现源码：

void Map2DCanvasEx::dragEnterEvent(QDragEnterEvent* event) {if (event->mimeData()->hasFormat("DragListView/code-text")) {if (event->source() == this) {event->setDropAction(Qt::MoveAction);event->accept();} else {event->acceptProposedAction();}} else {event->ignore();}}void Map2DCanvasEx::dropEvent(QDropEvent *event) {//判断接收的是否是指定的对象if (event->mimeData()->hasFormat("DragListView/code-text")) {//获取拖拽时设置的数据QByteArray itemData = event->mimeData()->data("DragListView/code-text");QDataStream dataStream(&itemData, QIODevice::ReadOnly);QString text;int selectJBCode = -1;dataStream >> selectJBCode >> text;JBPlotManagerInst()->addJB(event->pos());if (event->source() == this) {event->setDropAction(Qt::MoveAction);event->accept();} else {event->acceptProposedAction();}} else {event->ignore();}}

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