c++ qtreewidget支持撤销与恢复功能 示例

以下是一个简单的示例代码，演示如何在 `QTreeWidget` 中添加和删除节点，并支持撤销与恢复操作：

#include <QtWidgets>

class TreeItem : public QTreeWidgetItem
{
public:
    TreeItem(QTreeWidget* parent)
        : QTreeWidgetItem(parent)
    {
    }

    void setData(int column, int role, const QVariant& value) override
    {
        QTreeWidgetItem::setData(column, role, value);
        emitDataChanged();
    }

    void emitDataChanged()
    {
        emit dataChanged(this);
    }

signals:
    void dataChanged(QTreeWidgetItem* item);
};

class TreeUndoCommand : public QUndoCommand
{
public:
    TreeUndoCommand(QTreeWidget* treeWidget)
        : m_treeWidget(treeWidget)
    {
    }

protected:
    QTreeWidget* m_treeWidget;
};

class AddNodeCommand : public TreeUndoCommand
{
public:
    AddNodeCommand(QTreeWidget* treeWidget, QTreeWidgetItem* parent, const QStringList& texts, int index)
        : TreeUndoCommand(treeWidget), m_parent(parent), m_texts(texts), m_index(index)
    {
        setText("Add Node");
    }

    void undo() override
    {
        QTreeWidgetItem* item = m_parent->takeChild(m_index);
        delete item;
    }

    void redo() override
    {
        QTreeWidgetItem* item = new TreeItem(m_parent);
        item->setText(0, m_texts.at(0));
        m_parent->insertChild(m_index, item);
        m_treeWidget->setCurrentItem(item);

        QObject::connect(item, &TreeItem::dataChanged, this, &AddNodeCommand::onDataChanged);
    }

    void onDataChanged(QTreeWidgetItem* item)
    {
        setText("Add Node " + item->text(0));
    }

private:
    QTreeWidgetItem* m_parent;
    QStringList m_texts;
    int m_index;
};

class RemoveNodeCommand : public TreeUndoCommand
{
public:
    RemoveNodeCommand(QTreeWidget* treeWidget, QTreeWidgetItem* item)
        : TreeUndoCommand(treeWidget), m_item(item), m_parent(item->parent()), m_index(m_parent->indexOfChild(item))
    {
        setText("Remove Node");
        m_texts.append(item->text(0));
        for (int i = 0; i < item->childCount(); ++i) {
            QTreeWidgetItem* child = item->child(i);
            m_texts.append(child->text(0));
        }
    }

    void undo() override
    {
        QTreeWidgetItem* item = new TreeItem(m_parent);
        item->setText(0, m_texts.at(0));
        m_parent->insertChild(m_index, item);
        m_treeWidget->setCurrentItem(item);

        for (int i = 1; i < m_texts.size(); ++i) {
            QTreeWidgetItem* child = new TreeItem(item);
            child->setText(0, m_texts.at(i));
        }

        QObject::connect(item, &TreeItem::dataChanged, this, &RemoveNodeCommand::onDataChanged);
    }

    void redo() override
    {
        for (int i = m_item->childCount() - 1; i >= 0; --i) {
            QTreeWidgetItem* child = m_item->takeChild(i);
            delete child;
        }
        m_parent->takeChild(m_index);
        delete m_item;
    }

    void onDataChanged(QTreeWidgetItem* item)
    {
        setText("Remove Node " + item->text(0));
    }

private:
    QTreeWidgetItem* m_item;
    QTreeWidgetItem* m_parent;
    int m_index;
    QStringList m_texts;
};

int main(int argc, char* argv[])
{
    QApplication app(argc, argv);

    QTreeWidget treeWidget;
    treeWidget.setHeaderLabels({ "Name" });

    QUndoStack undoStack;

    QObject::connect(&treeWidget, &QTreeWidget::itemDoubleClicked, [&](QTreeWidgetItem* item, int column) {
        Q_UNUSED(column);
        item->setFlags(item->flags() | Qt::ItemIsEditable);
    });

    QObject::connect(&treeWidget, &QTreeWidget::itemChanged, [&](QTreeWidgetItem* item, int column) {
        Q_UNUSED(column);
        item->setFlags(item->flags() & ~Qt::ItemIsEditable);
        static_cast<TreeItem*>(item)->emitDataChanged();
    });

    QObject::connect(&treeWidget, &QTreeWidget::itemInserted, [&](QTreeWidgetItem* item, QTreeWidgetItem* parent, int index) {
        Q_UNUSED(index);
        AddNodeCommand* command = new AddNodeCommand(&treeWidget, parent, QStringList() << item->text(0), parent->indexOfChild(item));
        undoStack.push(command);
    });

    QObject::connect(&treeWidget, &QTreeWidget::itemRemoved, [&](QTreeWidgetItem* item) {
        RemoveNodeCommand* command = new RemoveNodeCommand(&treeWidget, item);
        undoStack.push(command);
    });

    // 添加根节点
    QTreeWidgetItem* root = new TreeItem(&treeWidget);
    root->setText(0, "Root");

    // 添加子节点
    QTreeWidgetItem* child1 = new TreeItem(root);
    child1->setText(0, "Child1");

    QTreeWidgetItem* child2 = new TreeItem(root);
    child2->setText(0, "Child2");

    // 设置当前项
    treeWidget.setCurrentItem(child2);

    // 显示窗口
    treeWidget.show();

    return app.exec();
}

在上面的代码中，我们定义了 `TreeItem` 类来代替 `QTreeWidgetItem` 类，它添加了一个 `dataChanged` 信号，用于在节点数据发生变化时发出信号。我们还定义了 `TreeUndoCommand` 类，它继承自 `QUndoCommand` 类，用于管理撤销与恢复操作。然后，我们分别定义了 `AddNodeCommand` 和 `RemoveNodeCommand` 类，分别代表添加节点和删除节点的操作。

在 `main` 函数中，我们创建了一个 `QTreeWidget` 对象和一个 `QUndoStack` 对象，并将相应的信号与 `QUndoStack` 对象的插入操作和删除操作连接起来。我们还添加了根节点和子节点，并设置了当前项。

在程序运行时，我们可以双击节点来编辑节点名称，也可以右键菜单中选择添加节点或删除节点来进行相应的操作，然后可以使用撤销和恢复按钮或快捷键来撤销和恢复操作。