c++代码实现qtreewidget支持撤销重做

实现Qt的QTreeWidget支持撤销重做，可以通过继承QTreeWidget实现自定义的树控件，并在其中添加撤销和重做操作。

具体实现步骤如下：

1. 定义一个结构体用于表示撤销/重做的操作，包含操作类型（如插入、删除、修改等）以及操作前后的节点信息。

struct TreeOperation {
    enum Type { Insert, Remove, Move, Update };
    Type type;
    QTreeWidgetItem *parent;
    int index;
    QTreeWidgetItem *node;
    QString text;
    QVariant data;
};

2. 在自定义的树控件中定义一个QStack用于存储操作记录，以及两个指针用于记录当前的撤销和重做操作。

class UndoableTreeWidget : public QTreeWidget {
    Q_OBJECT
public:
    UndoableTreeWidget(QWidget *parent = nullptr);
    ~UndoableTreeWidget();
public slots:
    void undo();
    void redo();
protected:
    void keyPressEvent(QKeyEvent *event) override;
    void mousePressEvent(QMouseEvent *event) override;
private:
    void pushOperation(const TreeOperation &op);
    void performOperation(const TreeOperation &op);
    void removeNode(QTreeWidgetItem *node);
    void insertNode(QTreeWidgetItem *parent, int index, QTreeWidgetItem *node);
    void moveNode(QTreeWidgetItem *parent, int from, int to);
    void updateNode(QTreeWidgetItem *node, const QString &text, const QVariant &data);
    QStack<TreeOperation> m_undoStack;
    QStack<TreeOperation> m_redoStack;
    TreeOperation *m_currentOp;
};

3. 在自定义的树控件的构造函数中，连接撤销和重做操作的信号和槽。

UndoableTreeWidget::UndoableTreeWidget(QWidget *parent) : QTreeWidget(parent) {
    m_currentOp = nullptr;
    connect(this, &QTreeWidget::itemChanged, [this](QTreeWidgetItem *item, int column) {
        if (m_currentOp == nullptr) {
            pushOperation({ TreeOperation::Update, item->parent(), indexOfTopLevelItem(item->parent()), item, item->text(column), item->data(column) });
        }
    });

    QAction *undoAction = new QAction(tr("&Undo"), this);
    undoAction->setShortcuts(QKeySequence::Undo);
    connect(undoAction, &QAction::triggered, this, &UndoableTreeWidget::undo);
    addAction(undoAction);

    QAction *redoAction = new QAction(tr("&Redo"), this);
    redoAction->setShortcuts(QKeySequence::Redo);
    connect(redoAction, &QAction::triggered, this, &UndoableTreeWidget::redo);
    addAction(redoAction);
}

4. 实现撤销和重做操作的槽函数。在撤销操作中，将当前操作记录到重做栈中，然后执行撤销操作；在重做操作中，将当前操作记录到撤销栈中，然后执行重做操作。

void UndoableTreeWidget::undo() {
    if (!m_undoStack.isEmpty()) {
        TreeOperation op = m_undoStack.pop();
        m_currentOp = &op;
        m_redoStack.push(op);
        performOperation(op);
        m_currentOp = nullptr;
    }
}

void UndoableTreeWidget::redo() {
    if (!m_redoStack.isEmpty()) {
        TreeOperation op = m_redoStack.pop();
        m_currentOp = &op;
        m_undoStack.push(op);
        performOperation(op);
        m_currentOp = nullptr;
    }
}

5. 实现各种操作的函数。在每个操作函数中，记录操作类型和节点信息，并将操作记录添加到撤销栈中。

void UndoableTreeWidget::removeNode(QTreeWidgetItem *node) {
    TreeOperation op = { TreeOperation::Remove, node->parent(), indexOfTopLevelItem(node->parent()), node, node->text(0), node->data(0) };
    pushOperation(op);
    delete node;
}

void UndoableTreeWidget::insertNode(QTreeWidgetItem *parent, int index, QTreeWidgetItem *node) {
    TreeOperation op = { TreeOperation::Insert, parent, index, node, "", QVariant() };
    pushOperation(op);
    parent->insertChild(index, node);
}

void UndoableTreeWidget::moveNode(QTreeWidgetItem *parent, int from, int to) {
    TreeOperation op = { TreeOperation::Move, parent, to, parent->child(from), "", QVariant() };
    pushOperation(op);
    parent->insertChild(to, parent->takeChild(from));
}

void UndoableTreeWidget::updateNode(QTreeWidgetItem *node, const QString &text, const QVariant &data) {
    TreeOperation op = { TreeOperation::Update, node->parent(), indexOfTopLevelItem(node->parent()), node, node->text(0), node->data(0) };
    pushOperation(op);
    node->setText(0, text);
    node->setData(0, Qt::UserRole, data);
}

6. 实现处理操作记录的函数。在每个操作函数中，根据操作类型执行相应的操作，并将操作记录添加到重做栈中。

void UndoableTreeWidget::performOperation(const TreeOperation &op) {
    switch (op.type) {
    case TreeOperation::Insert:
        removeNode(op.node);
        break;
    case TreeOperation::Remove:
        insertNode(op.parent, op.index, op.node);
        break;
    case TreeOperation::Move:
        moveNode(op.parent, op.index, indexOfTopLevelItem(op.node));
        break;
    case TreeOperation::Update:
        updateNode(op.node, op.text, op.data);
        break;
    }
    m_redoStack.clear();
}

void UndoableTreeWidget::pushOperation(const TreeOperation &op) {
    if (m_currentOp == nullptr || m_currentOp->node != op.node) {
        m_undoStack.push(op);
        m_redoStack.clear();
    }
}

7. 重载QTreeWidget的键盘和鼠标事件处理函数，以便在用户进行新增、删除和移动节点操作时记录操作记录。

void UndoableTreeWidget::keyPressEvent(QKeyEvent *event) {
    if (event->key() == Qt::Key_Delete) {
        QList<QTreeWidgetItem *> selectedItems = selectedItems();
        for (QTreeWidgetItem *item : selectedItems) {
            removeNode(item);
        }
    }
    QTreeWidget::keyPressEvent(event);
}

void UndoableTreeWidget::mousePressEvent(QMouseEvent *event) {
    if (event->button() == Qt::LeftButton) {
        QTreeWidgetItem *item = itemAt(event->pos());
        if (item) {
            setItemSelected(item, true);
        }
    }
    QTreeWidget::mousePressEvent(event);
}

以上就是实现Qt的QTreeWidget支持撤销重做的步骤和代码。