通过上一篇博文《Qt中自定义只读TreeView的Model》，我们介绍了用C++如何写一个只读TreeView的Model，接下来我们需要其具有编辑功能。
类比自定义ListView的Model，我们发现，让其具有可编辑功能，只需要加三个必要的接口：

Qt::ItemFlags flags(const QModelIndex &index) const override;

bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) override;

//在自定义模型中实现TreeView标题的修改
bool setHeaderData(int section, Qt::Orientation orientation, 
                   const QVariant &value, int role = Qt::EditRole) override;

另外我们需要有插入多行和插入多列、删除多行、插入多行和删除多行接口：

 bool insertColumns(int position, int columns, const QModelIndex &parent = QModelIndex()) override;
 bool removeColumns(int position, int columns, const QModelIndex &parent = QModelIndex()) override;
 bool insertRows(int position, int rows, const QModelIndex &parent = QModelIndex()) override;
 bool removeRows(int position, int rows, const QModelIndex &parent = QModelIndex()) override;

这样，我们就可以在只读Model上添加这些接口，将其改造成一个可读、可编辑的Model。
treeitem.h

#ifndef TREEITEM_H
#define TREEITEM_H

#include <QList>
#include <QVariant>
#include <QVector>

class TreeItem
{
public:
    explicit TreeItem(const QVector<QVariant> &data, TreeItem *parent = nullptr);
    ~TreeItem();

    TreeItem *child(int number);
    int childCount() const;
    int columnCount() const;
    QVariant data(int column) const;
    int childNumber() const; //返回子项的行数，在只读模型中是int row() const;其实功能是一样的。
    TreeItem *parent();

    //可以编辑模式 begin
    bool insertChildren(int position, int count, int columns);
    bool insertColumns(int position, int columns);

    bool removeChildren(int position, int count);
    bool removeColumns(int position, int columns);

    bool setData(int column, const QVariant &value);
    //可以编辑模式 end

private:
    QList<TreeItem*> childItems;
    QVector<QVariant> itemData;
    TreeItem *parentItem;
};
#endif // TREEITEM_H

treeitem.cpp

#include <QStringList>
#include "treeitem.h"

TreeItem::TreeItem(const QVector<QVariant> &data, TreeItem *parent)
{
    parentItem = parent;
    itemData = data;
}

TreeItem::~TreeItem()
{
    qDeleteAll(childItems);
}

TreeItem *TreeItem::child(int number)
{
    return childItems.value(number);
}

int TreeItem::childCount() const
{
    return childItems.count();
}

int TreeItem::childNumber() const
{
    if (parentItem)
        return parentItem->childItems.indexOf(const_cast<TreeItem*>(this));

    return 0;
}

int TreeItem::columnCount() const
{
    return itemData.count();
}

QVariant TreeItem::data(int column) const
{
    return itemData.value(column);
}

bool TreeItem::insertChildren(int position, int count, int columns)
{
    if (position < 0 || position > childItems.size())
        return false;

    for (int row = 0; row < count; ++row) {
        QVector<QVariant> data(columns);
        TreeItem *item = new TreeItem(data, this);
        childItems.insert(position, item);
    }

    return true;
}

bool TreeItem::insertColumns(int position, int columns)
{
    if (position < 0 || position > itemData.size())
        return false;

    for (int column = 0; column < columns; ++column)
        itemData.insert(position, QVariant());

    foreach (TreeItem *child, childItems)
        child->insertColumns(position, columns);

    return true;
}

TreeItem *TreeItem::parent()
{
    return parentItem;
}

bool TreeItem::removeChildren(int position, int count)
{
    if (position < 0 || position + count > childItems.size())
        return false;

    for (int row = 0; row < count; ++row)
        delete childItems.takeAt(position);

    return true;
}

bool TreeItem::removeColumns(int position, int columns)
{
    if (position < 0 || position + columns > itemData.size())
        return false;

    for (int column = 0; column < columns; ++column)
        itemData.remove(position);

    foreach (TreeItem *child, childItems)
        child->removeColumns(position, columns);

    return true;
}

bool TreeItem::setData(int column, const QVariant &value)
{
    if (column < 0 || column >= itemData.size())
        return false;

    itemData[column] = value;
    return true;
}

treemodel.h

#ifndef TREEMODEL_H
#define TREEMODEL_H

#include <QAbstractItemModel>
#include <QModelIndex>
#include <QVariant>

class TreeItem;

class TreeModel : public QAbstractItemModel
{
    Q_OBJECT

public:
    TreeModel(const QStringList &headers, QObject *parent = nullptr);
    ~TreeModel() override;

    QVariant data(const QModelIndex &index, int role) const override;
    QVariant headerData(int section, Qt::Orientation orientation,
                        int role = Qt::DisplayRole) const override;

    QModelIndex index(int row, int column,
                      const QModelIndex &parent = QModelIndex()) const override;
    QModelIndex parent(const QModelIndex &index) const override;

    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
    int columnCount(const QModelIndex &parent = QModelIndex()) const override;

    //可以编辑模型begin
    Qt::ItemFlags flags(const QModelIndex &index) const override;
    bool setData(const QModelIndex &index, const QVariant &value,
                 int role = Qt::EditRole) override;
    bool setHeaderData(int section, Qt::Orientation orientation,
                       const QVariant &value, int role = Qt::EditRole) override;

    bool insertColumns(int position, int columns,
                       const QModelIndex &parent = QModelIndex()) override;
    bool removeColumns(int position, int columns,
                       const QModelIndex &parent = QModelIndex()) override;
    bool insertRows(int position, int rows,
                    const QModelIndex &parent = QModelIndex()) override;
    bool removeRows(int position, int rows,
                    const QModelIndex &parent = QModelIndex()) override;
    //可以编辑模型end

private:
    TreeItem *getItem(const QModelIndex &index) const;

    TreeItem *rootItem;
};
#endif // TREEMODEL_H

treemodel.cpp

#include <QtWidgets>

#include "treeitem.h"
#include "treemodel.h"

TreeModel::TreeModel(const QStringList &headers, QObject *parent)
    : QAbstractItemModel(parent)
{
//    QVector<QVariant> rootData;
//    foreach (QString header, headers)
//        rootData << header;

//    rootItem = new TreeItem(rootData);

    QVector<QVariant> rootData;
    rootData << "Title" << "summary";
    rootItem = new TreeItem(rootData);

    rootItem->insertChildren(rootItem->childCount(), 1, rootItem->columnCount());

    QVector<QVariant> gettingStartedData;
    gettingStartedData << "Getting Started" << "How to familiarize yourself with Qt Designer";
    rootItem->child(rootItem->childCount()-1)->setData(0, gettingStartedData[0]);
    rootItem->child(rootItem->childCount()-1)->setData(1, gettingStartedData[1]);

    TreeItem *gettingStartedItem = rootItem->child(rootItem->childCount()-1);
    gettingStartedItem->insertChildren(gettingStartedItem->childCount(), 1, rootItem->columnCount());

    QVector<QVariant> launchingDesignerData;
    launchingDesignerData << "Launching Designer" << "Running the Qt Designer application";
    gettingStartedItem->child(gettingStartedItem->childCount()-1)->setData(0, launchingDesignerData[0]);
    gettingStartedItem->child(gettingStartedItem->childCount()-1)->setData(1, launchingDesignerData[1]);

    gettingStartedItem->insertChildren(gettingStartedItem->childCount(), 1, rootItem->columnCount());
    QVector<QVariant> userInterfaceData;
    userInterfaceData << "The User Interface" << "How to interact with Qt Designer";
    gettingStartedItem->child(gettingStartedItem->childCount()-1)->setData(0, userInterfaceData[0]);
    gettingStartedItem->child(gettingStartedItem->childCount()-1)->setData(1, userInterfaceData[1]);

    QVector<QVariant> designingComponentData;
    designingComponentData << "Designing a Component" << "Creating a GUI for your application";
    rootItem->insertChildren(rootItem->childCount(), 1, rootItem->columnCount());
    rootItem->child(rootItem->childCount()-1)->setData(0, designingComponentData[0]);
    rootItem->child(rootItem->childCount()-1)->setData(1, designingComponentData[1]);

    TreeItem *designingComponentItem = rootItem->child(rootItem->childCount()-1);

    QVector<QVariant> creatingDialogData;
    creatingDialogData << "Creating a Dialog" << "How to create a dialog";

    QVector<QVariant> composingDialogData;
    composingDialogData << "Composing the Dialog" << "Putting widgets into the dialog example";

    designingComponentItem->insertChildren(designingComponentItem->childCount(), 2, rootItem->columnCount());
    designingComponentItem->child(0)->setData(0, creatingDialogData[0]);
    designingComponentItem->child(0)->setData(1, creatingDialogData[1]);

    designingComponentItem->child(1)->setData(0, composingDialogData[0]);
    designingComponentItem->child(1)->setData(1, composingDialogData[1]);
}

TreeModel::~TreeModel()
{
    delete rootItem;
}

int TreeModel::columnCount(const QModelIndex & /* parent */) const
{
    return rootItem->columnCount();
}

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

    if (role != Qt::DisplayRole && role != Qt::EditRole)
        return QVariant();

    TreeItem *item = getItem(index);

    return item->data(index.column());
}

Qt::ItemFlags TreeModel::flags(const QModelIndex &index) const
{
    if (!index.isValid())
        return 0;

    return Qt::ItemIsEditable | QAbstractItemModel::flags(index);
}

TreeItem *TreeModel::getItem(const QModelIndex &index) const
{
    if (index.isValid()) {
        TreeItem *item = static_cast<TreeItem*>(index.internalPointer());
        if (item)
            return item;
    }
    return rootItem;
}


QVariant TreeModel::headerData(int section, Qt::Orientation orientation,
                               int role) const
{
    if (orientation == Qt::Horizontal && role == Qt::DisplayRole)
        return rootItem->data(section);

    return QVariant();
}


QModelIndex TreeModel::index(int row, int column, const QModelIndex &parent) const
{
    if (parent.isValid() && parent.column() != 0)
        return QModelIndex();

    TreeItem *parentItem = getItem(parent);

    TreeItem *childItem = parentItem->child(row);
    if (childItem)
        return createIndex(row, column, childItem);
    else
        return QModelIndex();
}


bool TreeModel::insertColumns(int position, int columns, const QModelIndex &parent)
{
    bool success;

    beginInsertColumns(parent, position, position + columns - 1);
    success = rootItem->insertColumns(position, columns);
    endInsertColumns();

    return success;
}

bool TreeModel::insertRows(int position, int rows, const QModelIndex &parent)
{
    TreeItem *parentItem = getItem(parent);
    bool success;

    beginInsertRows(parent, position, position + rows - 1);
    success = parentItem->insertChildren(position, rows, rootItem->columnCount());
    endInsertRows();

    return success;
}


QModelIndex TreeModel::parent(const QModelIndex &index) const
{
    if (!index.isValid())
        return QModelIndex();

    TreeItem *childItem = getItem(index);
    TreeItem *parentItem = childItem->parent();

    if (parentItem == rootItem)
        return QModelIndex();

    return createIndex(parentItem->childNumber(), 0, parentItem);
}

bool TreeModel::removeColumns(int position, int columns, const QModelIndex &parent)
{
    bool success;

    beginRemoveColumns(parent, position, position + columns - 1);
    success = rootItem->removeColumns(position, columns);
    endRemoveColumns();

    if (rootItem->columnCount() == 0)
        removeRows(0, rowCount());

    return success;
}

bool TreeModel::removeRows(int position, int rows, const QModelIndex &parent)
{
    TreeItem *parentItem = getItem(parent);
    bool success = true;

    beginRemoveRows(parent, position, position + rows - 1);
    success = parentItem->removeChildren(position, rows);
    endRemoveRows();

    return success;
}

int TreeModel::rowCount(const QModelIndex &parent) const
{
    TreeItem *parentItem = getItem(parent);

    return parentItem->childCount();
}

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

    TreeItem *item = getItem(index);
    bool result = item->setData(index.column(), value);

    if (result)
        emit dataChanged(index, index);

    return result;
}

bool TreeModel::setHeaderData(int section, Qt::Orientation orientation,
                              const QVariant &value, int role)
{
    if (role != Qt::EditRole || orientation != Qt::Horizontal)
        return false;

    bool result = rootItem->setData(section, value);

    if (result)
        emit headerDataChanged(orientation, section, section);

    return result;
}

main.cpp

#include <QApplication>
#include <QStringList>
#include <QTreeView>

#include "treemodel.h"

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

    QStringList headers;
    headers << "Title" << "Description";

    TreeModel *model = new TreeModel(headers);

    QTreeView view;
    view.setModel(model);
    for (int column = 0; column < model->columnCount(); ++column)
        view.resizeColumnToContents(column);

    view.show();

    return a.exec();
}

运行效果：