Qt MVC示例 simpletreemodel 树模型

从文本中读取树模型数据，缩进代表子项

TreeItem

表示一行字符串数据

treeitem.h

#ifndef TREEITEM_H
#define TREEITEM_H

#include <QList>
#include <QVariant>

//! [0]
class TreeItem
{
public:
    explicit TreeItem(const QList<QVariant> &data, TreeItem *parentItem = 0);
    ~TreeItem();

    void appendChild(TreeItem *child);

    TreeItem *child(int row);
    int childCount() const;
    int columnCount() const;
    QVariant data(int column) const;
    int row() const;
    TreeItem *parentItem();

private:
    QList<TreeItem*> m_childItems;
    QList<QVariant> m_itemData;
    TreeItem *m_parentItem;
};
//! [0]

#endif // TREEITEM_H

treeitem.cpp

/*
    treeitem.cpp

    A container for items of data supplied by the simple tree model.
*/

#include <QStringList>

#include "treeitem.h"

//! [0] 当前项数据data,父项parent
TreeItem::TreeItem(const QList<QVariant> &data, TreeItem *parent)
{
    m_parentItem = parent;
    m_itemData = data;
}
//! [0]

//! [1]
TreeItem::~TreeItem()
{
    qDeleteAll(m_childItems);
}
//! [1]

//! [2] 添加子项
void TreeItem::appendChild(TreeItem *item)
{
    m_childItems.append(item);
}
//! [2]

//! [3] 子项,通过行索引返回
TreeItem *TreeItem::child(int row)
{
    return m_childItems.value(row);
}
//! [3]

//! [4] 子项数
int TreeItem::childCount() const
{
    return m_childItems.count();
}
//! [4]

//! [5] 列数
int TreeItem::columnCount() const
{
    return m_itemData.count();
}
//! [5]

//! [6] 列数据,索引每一列的字符串单词
QVariant TreeItem::data(int column) const
{
    return m_itemData.value(column);
}
//! [6]

//! [7] 父项
TreeItem *TreeItem::parentItem()
{
    return m_parentItem;
}
//! [7]

//! [8] 默认返回0行,代表Item 只是1项
int TreeItem::row() const
{
    if (m_parentItem)
        return m_parentItem->m_childItems.indexOf(const_cast<TreeItem*>(this));

    return 0;
}
//! [8]

TreeModel

树模型

treemodel.h

#ifndef TREEMODEL_H
#define TREEMODEL_H

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

class TreeItem;

//! [0]
class TreeModel : public QAbstractItemModel
{
    Q_OBJECT

public:
    explicit TreeModel(const QString &data, QObject *parent = 0);
    ~TreeModel();

    QVariant data(const QModelIndex &index, int role) const override;
    Qt::ItemFlags flags(const QModelIndex &index) 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;

private:
    void setupModelData(const QStringList &lines, TreeItem *parent);

    TreeItem *rootItem;
};
//! [0]

#endif // TREEMODEL_H

treemodel.cpp

/*
    treemodel.cpp

    Provides a simple tree model to show how to create and use hierarchical
    models.
*/

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

#include <QStringList>

//! [0]
TreeModel::TreeModel(const QString &data, QObject *parent)
    : QAbstractItemModel(parent)
{
    QList<QVariant> rootData;
    rootData << "Title" << "Summary";
    rootItem = new TreeItem(rootData);
    setupModelData(data.split(QString("\n")), rootItem);
}
//! [0]

//! [1]
TreeModel::~TreeModel()
{
    delete rootItem;
}
//! [1]

//! [2]
int TreeModel::columnCount(const QModelIndex &parent) const
{
    if (parent.isValid())
        return static_cast<TreeItem*>(parent.internalPointer())->columnCount();
    else
        return rootItem->columnCount();
}
//! [2]

//! [3]
QVariant TreeModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid())
        return QVariant();

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

    TreeItem *item = static_cast<TreeItem*>(index.internalPointer());

    return item->data(index.column());
}
//! [3]

//! [4]
Qt::ItemFlags TreeModel::flags(const QModelIndex &index) const
{
    if (!index.isValid())
        return 0;

    return QAbstractItemModel::flags(index);
}
//! [4]

//! [5]
QVariant TreeModel::headerData(int section, Qt::Orientation orientation,
                               int role) const
{
    if (orientation == Qt::Horizontal && role == Qt::DisplayRole)
        return rootItem->data(section);

    return QVariant();
}
//! [5]

//! [6]
QModelIndex TreeModel::index(int row, int column, const QModelIndex &parent)
            const
{
    if (!hasIndex(row, column, parent))
        return QModelIndex();

    TreeItem *parentItem;

    if (!parent.isValid())
        parentItem = rootItem;
    else
        parentItem = static_cast<TreeItem*>(parent.internalPointer());

    TreeItem *childItem = parentItem->child(row);
    if (childItem)
        return createIndex(row, column, childItem);
    else
        return QModelIndex();
}
//! [6]

//! [7]
QModelIndex TreeModel::parent(const QModelIndex &index) const
{
    if (!index.isValid())
        return QModelIndex();

    TreeItem *childItem = static_cast<TreeItem*>(index.internalPointer());
    TreeItem *parentItem = childItem->parentItem();

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

    return createIndex(parentItem->row(), 0, parentItem);
}
//! [7]

//! [8]
int TreeModel::rowCount(const QModelIndex &parent) const
{
    TreeItem *parentItem;
    if (parent.column() > 0)
        return 0;

    if (!parent.isValid())
        parentItem = rootItem;
    else
        parentItem = static_cast<TreeItem*>(parent.internalPointer());

    return parentItem->childCount();
}
//! [8]

void TreeModel::setupModelData(const QStringList &lines, TreeItem *parent)
{
    QList<TreeItem*> parents;//父项
    QList<int> indentations;//代表行缩进索引位置
    parents << parent;
    indentations << 0;//默认缩进0位置

    int number = 0;//当前行号

    while (number < lines.count()) {
        int position = 0;//当前行的列索引
        while (position < lines[number].length()) {
            if (lines[number].at(position) != ' ')
                break;
            position++;
        }

        QString lineData = lines[number].mid(position).trimmed();

        if (!lineData.isEmpty()) {
            // Read the column data from the rest of the line.
            QStringList columnStrings = lineData.split("\t", QString::SkipEmptyParts);
            QList<QVariant> columnData;
            for (int column = 0; column < columnStrings.count(); ++column)
                columnData << columnStrings[column];

            if (position > indentations.last()) {//表示遇到缩进,即是新的子项
                // The last child of the current parent is now the new parent
                // unless the current parent has no children.

                if (parents.last()->childCount() > 0) {//当前父项最后一个子项添加为父项
                    parents << parents.last()->child(parents.last()->childCount()-1);
                    indentations << position;//更新行索引位置
                }
            } else {
                while (position < indentations.last() && parents.count() > 0) {//返回上一级
                    parents.pop_back();
                    indentations.pop_back();
                }
            }

            // Append a new item to the current parent's list of children.
            parents.last()->appendChild(new TreeItem(columnData, parents.last()));
        }

        ++number;//更新行号
    }
}