treemodel.cpp

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

#include <QtWidgets>

//! [0]
TreeModel::TreeModel(const QStringList &headers, const QString &data, QObject *parent)
    : QAbstractItemModel(parent)
{
    QVector<QVariant> rootData;
    for (const QString &header : headers)
        rootData << header;

    rootItem = new TreeItem(rootData);
    setupModelData(data.split('\n'), rootItem);
}
//! [0]

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

//! [2]
int TreeModel::columnCount(const QModelIndex &parent) const
{
    Q_UNUSED(parent);
    return rootItem->columnCount();
}
//! [2]

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());
}

//! [3]
Qt::ItemFlags TreeModel::flags(const QModelIndex &index) const
{
    if (!index.isValid())
        return Qt::ItemIsDropEnabled | Qt::NoItemFlags;

    return Qt::ItemIsDragEnabled | Qt::ItemIsDropEnabled | Qt::ItemIsEditable | QAbstractItemModel::flags(index);
}
//! [3]

//! [4]
TreeItem *TreeModel::getItem(const QModelIndex &index) const
{
    if (index.isValid()) {
        TreeItem *item = static_cast<TreeItem*>(index.internalPointer());
        if (item)
            return item;
    }
    return rootItem;
}
//! [4]

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]
QModelIndex TreeModel::index(int row, int column, const QModelIndex &parent) const
{
    if (parent.isValid() && parent.column() != 0)
        return QModelIndex();
//! [5]

//! [6]
    TreeItem *parentItem = getItem(parent);
    if (!parentItem)
        return QModelIndex();

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

bool TreeModel::insertColumns(int position, int columns, const QModelIndex &parent)
{
    beginInsertColumns(parent, position, position + columns - 1);
    const bool success = rootItem->insertColumns(position, columns);
    endInsertColumns();

    return success;
}

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

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

    return success;
}

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

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

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

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

bool TreeModel::removeColumns(int position, int columns, const QModelIndex &parent)
{
    beginRemoveColumns(parent, position, position + columns - 1);
    const bool 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);
    if (!parentItem)
        return false;

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

    return success;
}

//! [8]
int TreeModel::rowCount(const QModelIndex &parent) const
{
    const TreeItem *parentItem = getItem(parent);

    return parentItem ? parentItem->childCount() : 0;
}
//! [8]

bool TreeModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
    Q_UNUSED(role)

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

// Original version: why restrict roles to just EditRole? Accept them all
// In fact, not accepting DisplayRole is buggy, as it does not copy data properly; see
// https://stackoverflow.com/questions/67292806/qt-attempt-to-add-drag-and-drop-to-editable-tree-model-example-not-working/

//    if (role != Qt::EditRole)
//        result = false;
//    else {
//        TreeItem *item = getItem(index);
//        result = item->setData(index.column(), value);
//    }
//    if (result)
//        emit dataChanged(index, index);//, {Qt::EditRole});  // update all roles so that tree structure decoration is updated

//    return result;
}

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

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

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

    return result;
}

Qt::DropActions TreeModel::supportedDropActions() const
{
    return Qt::CopyAction | Qt::MoveAction;
}

void TreeModel::setupModelData(const QStringList &lines, TreeItem *parent)
{
    QVector<TreeItem*> parents;
    QVector<int> indentations;
    parents << parent;
    indentations << 0;

    int number = 0;

    while (number < lines.count()) {
        int position = 0;
        while (position < lines[number].length()) {
            if (lines[number].at(position) != ' ')
                break;
            ++position;
        }

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

        if (!lineData.isEmpty()) {
            // Read the column data from the rest of the line.
            const QStringList columnStrings =
                lineData.split(QLatin1Char('\t'), Qt::SkipEmptyParts);
            QVector<QVariant> columnData;
            columnData.reserve(columnStrings.size());
            for (const QString &columnString : columnStrings)
                columnData << columnString;

            if (position > indentations.last()) {
                // The last child of the current parent is now the new parent
                // unless the current parent has no children.

                if (parents.last()->childCount() > 0) {
                    parents << parents.last()->child(parents.last()->childCount()-1);
                    indentations << position;
                }
            } else {
                while (position < indentations.last() && parents.count() > 0) {
                    parents.pop_back();
                    indentations.pop_back();
                }
            }

            // Append a new item to the current parent's list of children.
            TreeItem *parent = parents.last();
            parent->insertChildren(parent->childCount(), 1, rootItem->columnCount());
            for (int column = 0; column < columnData.size(); ++column)
                parent->child(parent->childCount() - 1)->setData(column, columnData[column]);
        }
        ++number;
    }
}