Displaying Qt tree through QAbstractItemModel and QModelIndex - c++

Question

I'm trying to display a user defined tree Family_tree through a TreeModel class derived from QAbstractItemModel containing a Family_tree ft_ member and the overrides for the index, parent, data etc methods.
I rewrote the methods using the Family_tree nodes and I'm calling them from MainWindow like shown below (I double checked Family_tree and it is being set up correctly). All I see is empty space with a single '1' appearing on the top left corner since I have columnCount return 1 for all the nodes and I'm starting by trying to display a tree with only one node (I only expect icons to show up).
Am I misinterpreting how this works in any way? I would really appreciate some insight, thank you for your time!
MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) {
inh_pattern = AD;
patient = new Patient("Nancy Kalaj", Date(12, 12, 1997), 25, 'F', Genotype("DD"), Date());
family = new Family_tree(*patient);
selected = new SelectedPatient(); selected->setSelectedPatient(patient);
patientOverview = new PatientOverview(*patient, *selected, this); patientOverview->show();
patientRelatives = new PatientRelatives(*family, *selected, this);
treeModel = new TreeModel(*family);
QTreeView* view = new QTreeView(this);
view->setModel(treeModel);
//...
}
QModelIndex TreeModel::index(int row, int column, const QModelIndex& parent) const {
if (!hasIndex(row, column, parent)) {return QModelIndex();}
node* parentNode;
if (!parent.isValid()) {parentNode = ft_.get_root();}
else {parentNode = static_cast<node*>(parent.internalPointer());}
node* childNode = parentNode->getChildren()[row];
if (childNode) {return createIndex(row, column, childNode);}
else {return QModelIndex();}
}
QModelIndex TreeModel::parent(const QModelIndex& index) const {
if (!index.isValid()) {return QModelIndex();}
node* n = static_cast<node*>(index.internalPointer());
node* parentNode = n->getParent();
if (parentNode == ft_.get_root()) {return QModelIndex();}
return createIndex(row(parentNode), 0, parentNode);
}
bool TreeModel::hasChildren(const QModelIndex& parent) const {
if (!parent.isValid()) {
return true;
}
node* n = static_cast<node*>(parent.internalPointer());
return !n->getChildren().empty();
}
int TreeModel::rowCount(const QModelIndex& parent) const {
node* parentNode;
if (parent.column() > 0) {return 0;}
if (!parent.isValid()) {parentNode = ft_.get_root();}
else {parentNode = static_cast<node*>(parent.internalPointer());}
return parentNode->getChildren().size();
}
int TreeModel::columnCount(const QModelIndex& parent) const {
return 1;
}
QVariant TreeModel::data(const QModelIndex &index, int role) const {
if (!index.isValid()) {return QVariant();}
node* n = static_cast<node*>(index.internalPointer());
if (role == Qt::DecorationRole) {
if (index.column() == 0) {
QPixmap pixmap(16, 16);
pixmap.fill(Qt::black);
QPainter painter(&pixmap);
painter.setBrush(Qt::white);
painter.drawRect(0, 0, 15, 15);
return QIcon(pixmap);
}
else {return QVariant();}
}
return QVariant();
}
Qt::ItemFlags TreeModel::flags(const QModelIndex& index) const {
if (!index.isValid()) {return Qt::NoItemFlags;}
return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
}