Simple way to expand all nodes on a QTreeView?

[Pieter from Belgium]

Hehe, thinking the same thing at the same time . However I must admit you put it more concise, and with the correct references.

QTreeView::itemsExpandable [as referred to in the feature rejection] does not help in this issue, as it can only be used to prevent the default collapsed item to be expanded...

[fullmetalcoder]

Qt 4.2 introduced QTreeView::expandAll(). Ain't that neat? And the feature reject mentions it BTW...

[jpn]

Qt 4.2 introduced QTreeView::expandAll(). Ain't that neat? And the feature reject mentions it BTW...

The point is that it's very expensive to call it for large models.

Warning: if the model contains a large number of items, this function will be take time to execute.

Now, consider a dynamically changing large model. You don't want to call QTreeView::expandAll() again and again, do you?

[evgeniy]

void MainWindow::expandNode(const QModelIndex &parentIndex, bool expand) {
  tree->setExpanded(parentIndex, expand);
  for (qint32 rowNum = 0; rowNum < treeModel->rowCount(parentIndex); ++rowNum) {
    QModelIndex childIndex = treeModel->index(rowNum, 0, parentIndex);
    tree->setExpanded(childIndex, expand);
    expandNode(childIndex);
  }
}

void MainWindow::expandNode(const QModelIndex &parentIndex, bool expand) {
  tree->setExpanded(parentIndex, expand);
  for (qint32 rowNum = 0; rowNum < treeModel->rowCount(parentIndex); ++rowNum) {
    QModelIndex childIndex = treeModel->index(rowNum, 0, parentIndex);
    tree->setExpanded(childIndex, expand);
    expandNode(childIndex);
  }
}

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