qt中用treewidget创建横向表格，实现两个treewidget能相互拖动item，并且只能拖动到到根节点的子节点同级节点

实现这个功能需要以下几个步骤： 1. 创建两个QTreeWidget，一个作为源，一个作为目标。 2. 设置源QTreeWidget为可拖动，目标QTreeWidget为可接受拖放。 ```cpp sourceWidget->setDragEnabled(true); targetWidget->setAcceptDrops(true); 3. 在源QTreeWidget的mousePressEvent事件中，记录被拖动的item和它的父节点。 ```cpp if (event->button() == Qt::LeftButton) { QTreeWidgetItem *item = sourceWidget->itemAt(event->pos()); if (item && item->parent()) { m_draggedItem = item; m_draggedParent = item->parent(); 4. 在源QTreeWidget的mouseMoveEvent事件中，如果鼠标移动的距离大于一定阈值，就开始拖拽操作。 ```cpp if (m_draggedItem && (event->buttons() & Qt::LeftButton)) { int distance = (event->pos() - m_pressPos).manhattanLength(); if (distance >= QApplication::startDragDistance()) { QDrag *drag = new QDrag(this); QMimeData *mimeData = new QMimeData; mimeData->setData("application/x-qabstractitemmodeldatalist", sourceWidget->model()->itemData(m_draggedItem).value<QByteArray>()); drag->setMimeData(mimeData); drag->exec(Qt::CopyAction | Qt::MoveAction, Qt::CopyAction); 5. 在目标QTreeWidget的dragEnterEvent和dragMoveEvent事件中，检查被拖动的item是否可以拖放到指定位置。如果不能，就设置禁止拖放的光标。 ```cpp if (event->mimeData()->hasFormat("application/x-qabstractitemmodeldatalist")) { QTreeWidgetItem *targetItem = this->itemAt(event->pos()); QTreeWidgetItem *parentItem = targetItem ? targetItem->parent() : this->invisibleRootItem(); if (parentItem == m_draggedParent) { event->accept(); } else { event->ignore(); this->setCursor(Qt::ForbiddenCursor); } else { event->ignore(); 6. 在目标QTreeWidget的dropEvent事件中，将被拖动的item插入到指定位置。 ```cpp if (event->mimeData()->hasFormat("application/x-qabstractitemmodeldatalist")) { QByteArray data = event->mimeData()->data("application/x-qabstractitemmodeldatalist"); QDataStream stream(&data, QIODevice::ReadOnly); QList<QVariant> itemData; QPoint offset; stream >> itemData >> offset; QTreeWidgetItem *targetItem = this->itemAt(event->pos()); QTreeWidgetItem *parentItem = targetItem ? targetItem->parent() : this->invisibleRootItem(); if (parentItem == m_draggedParent) { QTreeWidgetItem *newItem = new QTreeWidgetItem(parentItem, itemData); parentItem->insertChild(targetItem ? this->indexOfTopLevelItem(targetItem) : parentItem->childCount(), newItem); event->accept(); } else { event->ignore(); 完整的代码示例： ```cpp #include <QtWidgets> class TreeWidget : public QWidget { public: TreeWidget(QWidget *parent = nullptr) : QWidget(parent) { QVBoxLayout *layout = new QVBoxLayout(this); QHBoxLayout *hlayout = new QHBoxLayout; layout->addLayout(hlayout); m_sourceWidget = new QTreeWidget(this); m_sourceWidget->setColumnCount(1); m_sourceWidget->setHeaderHidden(true); m_sourceWidget->setDragEnabled(true); hlayout->addWidget(m_sourceWidget); m_targetWidget = new QTreeWidget(this); m_targetWidget->setColumnCount(1); m_targetWidget->setHeaderHidden(true); m_targetWidget->setAcceptDrops(true); hlayout->addWidget(m_targetWidget); QTreeWidgetItem *rootItem = new QTreeWidgetItem(m_sourceWidget, {"Root"}); QTreeWidgetItem *childItem = new QTreeWidgetItem(rootItem, {"Child"}); rootItem->addChild(childItem); connect(m_sourceWidget, &QTreeWidget::itemPressed, this, &TreeWidget::onSourceItemPressed); connect(m_targetWidget, &QTreeWidget::dragEnterEvent, this, &TreeWidget::onTargetDragEnter); connect(m_targetWidget, &QTreeWidget::dragMoveEvent, this, &TreeWidget::onTargetDragMove); connect(m_targetWidget, &QTreeWidget::dropEvent, this, &TreeWidget::onTargetDrop); void onSourceItemPressed(QTreeWidgetItem *item, int column) { Q_UNUSED(column) m_draggedItem = nullptr; m_draggedParent = nullptr; m_pressPos = QCursor::pos(); if (item && item->parent()) { m_draggedItem = item; m_draggedParent = item->parent(); void onTargetDragEnter(QDragEnterEvent *event) { if (event->mimeData()->hasFormat("application/x-qabstractitemmodeldatalist")) { QTreeWidgetItem *targetItem = m_targetWidget->itemAt(event->pos()); QTreeWidgetItem *parentItem = targetItem ? targetItem->parent() : m_targetWidget->invisibleRootItem(); if (parentItem == m_draggedParent) { event->accept(); } else { event->ignore(); m_targetWidget->setCursor(Qt::ForbiddenCursor); } else { event->ignore(); void onTargetDragMove(QDragMoveEvent *event) { if (event->mimeData()->hasFormat("application/x-qabstractitemmodeldatalist")) { QTreeWidgetItem *targetItem = m_targetWidget->itemAt(event->pos()); QTreeWidgetItem *parentItem = targetItem ? targetItem->parent() : m_targetWidget->invisibleRootItem(); if (parentItem == m_draggedParent) { event->accept(); } else { event->ignore(); m_targetWidget->setCursor(Qt::ForbiddenCursor); } else { event->ignore(); void onTargetDrop(QDropEvent *event) { if (event->mimeData()->hasFormat("application/x-qabstractitemmodeldatalist")) { QByteArray data = event->mimeData()->data("application/x-qabstractitemmodeldatalist"); QDataStream stream(&data, QIODevice::ReadOnly); QList<QVariant> itemData; QPoint offset; stream >> itemData >> offset; QTreeWidgetItem *targetItem = m_targetWidget->itemAt(event->pos()); QTreeWidgetItem *parentItem = targetItem ? targetItem->parent() : m_targetWidget->invisibleRootItem(); if (parentItem == m_draggedParent) { QTreeWidgetItem *newItem = new QTreeWidgetItem(parentItem, itemData); parentItem->insertChild(targetItem ? m_targetWidget->indexOfTopLevelItem(targetItem) : parentItem->childCount(), newItem); event->accept(); } else { event->ignore(); } else { event->ignore(); private: QTreeWidget *m_sourceWidget; QTreeWidget *m_targetWidget; QTreeWidgetItem *m_draggedItem; QTreeWidgetItem *m_draggedParent; QPoint m_pressPos; int main(int argc, char *argv[]) { QApplication app(argc, argv); TreeWidget widget; widget.show(); return app.exec(); ```