Qt 5.11 | Qt Widgets | Simple Tree Model Example | treemodel.cpp Example File

Qt 5.11.3 Reference Documentation

# treemodel.cpp Example File

itemviews/simpletreemodel/treemodel.cpp

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      /*
          treemodel.cpp

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

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

      #include <QStringList>

      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);
      }

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

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

      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());
      }

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

          return QAbstractItemModel::flags(index);
      }

      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 (!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();
      }

      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);
      }

      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();
      }

      void TreeModel::setupModelData(const QStringList &lines, TreeItem *parent)
      {
          QList<TreeItem*> parents;
          QList<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++;
              }

              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()) {
                      // 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.
                  parents.last()->appendChild(new TreeItem(columnData, parents.last()));
              }

              ++number;
          }
      }