Method eventFilter

src/frontend/ProjectExplorer.cpp:342–475

! handles the contextmenu-event of the horizontal header in the tree view. Provides a menu for selective showing and hiding of columns. */

	Provides a menu for selective showing and hiding of columns.
*/
bool ProjectExplorer::eventFilter(QObject* obj, QEvent* event) {
	if (obj == m_treeView->header() && event->type() == QEvent::ContextMenu) {
		// Menu for showing/hiding the columns in the tree view
		QMenu* columnsMenu = new QMenu(m_treeView->header());
		columnsMenu->addSection(i18n("Columns"));
		columnsMenu->addAction(showAllColumnsAction);
		columnsMenu->addSeparator();
		for (auto* action : std::as_const(list_showColumnActions))
			columnsMenu->addAction(action);

		auto* e = static_cast<QContextMenuEvent*>(event);
		columnsMenu->exec(e->globalPos());
		delete columnsMenu;

		return true;
	} else if (obj == m_treeView->viewport()) {
		if (event->type() == QEvent::MouseButtonPress) {
			auto* e = static_cast<QMouseEvent*>(event);
			const auto position = e->globalPosition().toPoint();
			if (e->button() == Qt::LeftButton) {
				QModelIndex index = m_treeView->indexAt(e->pos());
				if (!index.isValid())
					return false;

				auto* aspect = static_cast<AbstractAspect*>(index.internalPointer());
				if (aspect->isDraggable()) {
					m_dragStartPos = position;
					m_dragStarted = false;
				}
			}
		} else if (event->type() == QEvent::MouseMove) {
			auto* e = static_cast<QMouseEvent*>(event);
			const auto position = e->globalPosition().toPoint();
			if (!m_dragStarted && m_treeView->selectionModel()->selectedIndexes().size() > 0
				&& (position - m_dragStartPos).manhattanLength() >= QApplication::startDragDistance()) {
				m_dragStarted = true;
				auto* drag = new QDrag(this);
				auto* mimeData = new QMimeData;

				// determine the selected objects and serialize the pointers to QMimeData
				QVector<quintptr> vec;
				QModelIndexList items = m_treeView->selectionModel()->selectedIndexes();
				// there are four model indices in each row -> divide by 4 to obtain the number of selected rows (=aspects)
				const int columnCount = m_treeView->model()->columnCount();
				for (int i = 0; i < items.size() / columnCount; ++i) {
					const QModelIndex& index = items.at(i * columnCount);
					auto* aspect = static_cast<AbstractAspect*>(index.internalPointer());
					vec << (quintptr)aspect;
				}

				QByteArray data;
				QDataStream stream(&data, QIODevice::WriteOnly);
				stream << (quintptr)m_project; // serialize the project pointer first, will be used as the unique identifier
				stream << vec;

				mimeData->setData(QStringLiteral("labplot-dnd"), data);
				drag->setMimeData(mimeData);
				drag->exec();