QListView ScrollToBottom doesn't scroll to the very end

KodzghlyCZ

Hello
I want to achieve the 'Auto scroll' effect on QListView component, currently I am using scrollToBottom() function to get to the very end, but it always stays a little bit above the complete end of the list, see the image attached below.
I think there might be some feature in the QtDesigner that I haven't discovered yet, but I was not able to figure out how to scroll to the very end, so the bottom line doesn't get clipped this bad.
I am using Python with PySide6 and I am importing the ui file converted to the .py file using pyside6-uic tool.

Thanks to anybody answering, I really appreciate any piece of help, since I'm fairly new to the whole Qt stuff, but I like to learn and I hope my question is just not completely stupid.

The image:

SGaist

Hi and welcome to devnet,

Shouldn't you rather use scrollTo using QAbstractItemView::PositionAtBottom ?

KodzghlyCZ

I don't know if I'm doing anything wrong, but the code implemented throws me an exception

TypeError: 'PySide6.QtWidgets.QListView.scrollTo' called with wrong argument types:
  PySide6.QtWidgets.QListView.scrollTo(ScrollHint)
Supported signatures:
  PySide6.QtWidgets.QListView.scrollTo(PySide6.QtCore.QModelIndex, PySide6.QtWidgets.QAbstractItemView.ScrollHint = PySide6.QtWidgets.QAbstractItemView.ScrollHint.EnsureVisible)

The line I added looks like this:

self.ui.phpConsole.scrollTo(QAbstractItemView.PositionAtBottom)

I just changed the line mentioned previously with this one, but the error shows up.

SGaist

You are missing the index argument.

sebwr

@SGaist

Hey I tried it by creating an QModelIndex based on the current data of the model:

class LogModel(QAbstractListModel):
    ...
    def log(self, message: str):
        self.experiment_logs.append(message)
        self.layoutChanged.emit()
        current_index = self.createIndex(len(self.experiment_logs)-1, 0)
        self._list_view.scrollTo(current_index, QAbstractItemView.PositionAtBottom)

the following QModelIndex is returned in the last step:
<PySide6.QtCore.QModelIndex(100,0,0x0,LogModel(0x3d8ad00)) at 0x7f06c843a280>
where the "100" matches the length - 1 of the list which is the data structure behind the LogModel.

But when I call scrollTo, as suggested by you, nothing happends.

I am also tried the following (Which should be wrong, because the QModelIndex should also start at zero?):

current_index = self.createIndex(len(self.experiment_logs), 0)

Any further thoughts?

SGaist

Hi and welcome to devnet,

What does _list_view do in that model ? That's not its place.
Also, emitting layoutChanged for adding a row of data is wrong. There are two signals to signify that you are adding new data and when you are done, use them.

sebwr

@SGaist

Yes the _list_view was at the wrong place. I am now emitting a signal to the correct place.

I got it working with:

LogModel:

def log(self, message: str):
    self.experiment_logs.append(message)
    top_index = self.createIndex(self.rowCount()-2, 0)
    bottom_index = self.createIndex(self.rowCount()-1, 0)
    self.dataChanged.emit(top_index, bottom_index)

    self.signal.scroll_list_view.emit()

Main:

self.log_model.signal.scroll_list_view.connect(
    lambda: self.list_view_log.scrollToBottom()
)

So I guess the scrollToBottom works fine if the correct Signal is emitted?

SGaist

When you add data, there's a begin/endInsertRows pair of function that you should call. Their a responsible for notifying the view that things are changing with regard to the amount of the data.