c++ qtableview支持撤销重做 代码

以下是一个简单的实现示例，其中数据模型继承自 QAbstractTableModel 类：

class MyTableModel : public QAbstractTableModel
{
public:
    MyTableModel(QObject *parent = 0);

    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
    int columnCount(const QModelIndex &parent = QModelIndex()) const override;
    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
    bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) override;
    Qt::ItemFlags flags(const QModelIndex &index) const override;

    void undo();
    void redo();
    bool canUndo() const;
    bool canRedo() const;

private:
    QList<QList<QVariant>> m_data;
    QUndoStack *m_undoStack;
};

MyTableModel::MyTableModel(QObject *parent)
    : QAbstractTableModel(parent)
{
    // 初始化数据
    m_data = {
        {1, "apple", 5},
        {2, "banana", 3},
        {3, "orange", 4},
    };

    // 创建QUndoStack对象
    m_undoStack = new QUndoStack(this);
}

int MyTableModel::rowCount(const QModelIndex &parent) const
{
    Q_UNUSED(parent)
    return m_data.count();
}

int MyTableModel::columnCount(const QModelIndex &parent) const
{
    Q_UNUSED(parent)
    return 3;
}

QVariant MyTableModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid())
        return QVariant();

    if (role == Qt::DisplayRole || role == Qt::EditRole) {
        int row = index.row();
        int col = index.column();
        return m_data.at(row).at(col);
    }

    return QVariant();
}

bool MyTableModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
    if (!index.isValid() || role != Qt::EditRole)
        return false;

    int row = index.row();
    int col = index.column();
    QVariant oldValue = m_data.at(row).at(col);

    if (oldValue != value) {
        // 创建QUndoCommand对象，并将其放入QUndoStack中
        EditCommand *command = new EditCommand(this, row, col, oldValue, value);
        m_undoStack->push(command);

        // 更新数据
        m_data[row][col] = value;

        // 发出数据变更信号
        emit dataChanged(index, index, QVector<int>() << role);

        return true;
    }

    return false;
}

Qt::ItemFlags MyTableModel::flags(const QModelIndex &index) const
{
    if (!index.isValid())
        return Qt::NoItemFlags;

    return Qt::ItemIsEditable | Qt::ItemIsEnabled | Qt::ItemIsSelectable;
}

void MyTableModel::undo()
{
    if (m_undoStack->canUndo())
        m_undoStack->undo();
}

void MyTableModel::redo()
{
    if (m_undoStack->canRedo())
        m_undoStack->redo();
}

bool MyTableModel::canUndo() const
{
    return m_undoStack->canUndo();
}

bool MyTableModel::canRedo() const
{
    return m_undoStack->canRedo();
}

其中，EditCommand 是自定义的 QUndoCommand 子类，用于保存旧值和新值，并实现撤销和重做操作。以下是 EditCommand 类的实现：

class EditCommand : public QUndoCommand
{
public:
    EditCommand(MyTableModel *model, int row, int col, QVariant oldValue, QVariant newValue);

    void undo() override;
    void redo() override;

private:
    MyTableModel *m_model;
    int m_row;
    int m_col;
    QVariant m_oldValue;
    QVariant m_newValue;
};

EditCommand::EditCommand(MyTableModel *model, int row, int col, QVariant oldValue, QVariant newValue)
    : QUndoCommand()
{
    m_model = model;
    m_row = row;
    m_col = col;
    m_oldValue = oldValue;
    m_newValue = newValue;
}

void EditCommand::undo()
{
    m_model->setData(m_model->index(m_row, m_col), m_oldValue, Qt::EditRole);
}

void EditCommand::redo()
{
    m_model->setData(m_model->index(m_row, m_col), m_newValue, Qt::EditRole);
}

在 EditCommand 的构造函数中，保存了数据模型、行号、列号、旧值和新值，以便在撤销和重做时使用。

在 EditCommand 的 undo() 函数中，将数据模型的对应数据恢复为旧值；在 redo() 函数中，将数据模型的对应数据更新为新值。