Drop between items in QTreeWidget

Pete Sassafras

My QTreeWidget is created like in a code below:

treeWidget = new QTreeWidget(centralWidget);
treeWidget->setDragDropMode(QAbstractItemView::DragDrop);
treeWidget->setDefaultDropAction(Qt::MoveAction);
treeWidget->setVerticalScrollMode(QAbstractItemView::ScrollPerPixel);

Sometimes when i drag item and drop it between 2 other items it becomes top level insetd of beeing inserted where it supposed to. It happens only if VerticalScrollMode is QAbstractItemView::ScrollPerPixel and if item is dropped at red line ( on screenshot). Is there any way to avoid this behaviour?
alt text

SGaist

Hi and welcome to devnet,

You may have unearthed something. However, do you really need ScrollPerPixel ?

Pete Sassafras

With ScrollPerItem it scrolls too "jumpy". Anyway, I looked at sources and I think the problem is in

int QTreeViewPrivate::itemAtCoordinate	(	int 	coordinate	 ) 	const

There is if statement:

if (verticalScrollMode == QAbstractItemView::ScrollPerPixel) {
         if (uniformRowHeights) {
             const int viewItemIndex = (coordinate + q->verticalScrollBar()->value()) / defaultItemHeight;
             return (viewItemIndex >= itemCount ? -1 : viewItemIndex);
         }
         // ### optimize
         int viewItemCoordinate = 0;
         const int contentsCoordinate = coordinate + q->verticalScrollBar()->value();
         for (int viewItemIndex = 0; viewItemIndex < viewItems.count(); ++viewItemIndex) {
             viewItemCoordinate += itemHeight(viewItemIndex);
             if (viewItemCoordinate >= contentsCoordinate)  //here
                 return (viewItemIndex >= itemCount ? -1 : viewItemIndex);
         }
 }

And line

if (viewItemCoordinate >= contentsCoordinate)

should be like

if (viewItemCoordinate > contentsCoordinate)

So, if uniformRowHeight is true then everything works fine.

treeWidget->setUniformRowHeights(true);

SGaist

Good catch. You should check the bug report system to see if there's already something related. If not then you should open a report with your findings (and a minimal compilable example).

Solved Drop between items in QTreeWidget