QTreeView - Hide controls for expanding and collapsing specific items

pablo_worker

Hi,
I have a custom model (derived from QAbstractItemModel) that it is shown with a QTreeView.

When an item of the model has children, the QTreeView shows a expanding/collapsing icon (a triangle) that allows you to show/hide the children. I want to hide the icon on an specific item. This item has children so it has to be expanded always. I want to achieve the following style for the tree (I will use the symbols + and - as the expanding/collapsing icon)

A
 B
 C
 D <-I don't want to show the expanding/collapsing icon in this item.
  -E
    E1
    E2
  +F
  -G
    -G1
      G1.1
      G1.2
    G2

I have been able to hide the expanding/collapsing icon of the first item (the A) with the following command:

myQTreeView.setRootIsDecorated(false);

However, I don't know how to hide the icon for the item D in my example.

Any ideas?

Thank you.

michalos

I hope that someone will suggest a simpler solution, because mine would require some work, but:

You could use a custom item delegate (derived from QStyledItemDelegate) and override the paint() and sizeHint() method.

In paint() You draw what You need (icons, text, QTextDocument, etc.) for a specific item. You could use Qt::UserRole to specify the items, that need special drawing like this:

if(index.data(Qt::UserRole).toInt() == 1) { 
//draw differently 
} else { 
//draw standard
QStyledItemDelegate::paint(painter, option, index); 
}

In sizeHint() You declare the size of a single item.

http://doc.qt.io/qt-5/qstyleditemdelegate.html

http://doc.qt.io/qt-5/qtwidgets-itemviews-spinboxdelegate-example.html

I'm using this method for something slightly different, but it should work for You as well.

VRonin

rather than the delegate I'd reimplement QTreeView:
protected:

virtual void drawBranches(QPainter *painter, const QRect &rect, const QModelIndex &index) const
virtual void drawRow(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const

and slots

void collapse(const QModelIndex &index)
void expand(const QModelIndex &index)

But agree is not straightforward and will require some work