QTableView.verticalHeader().setOffset() doesn't work

[Matej Brezović]

Yes, seems like you're right. If I call setOffset() after calling show() on
my window, the offset is visible but disappears as soon as I try to resize
the window.
Calling it after resizeEvent or paintEvent doesn't seems to work either,
and if it did it would probably be inefficient. I don't really know why
does that function even exist if it doesn't seems to have an effect if the
view is resizable.
And yes, my intention was to simply add some padding, just a few pixels, on
the top of the first row, so that the table view would be slightly
separated from the header view, but it seems I will have to give up on that
idea.
Thanks for the fast responses! :)

<https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon>
Virus-free.
www.avast.com
<https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

On Sun, Mar 20, 2022 at 8:07 PM Maurizio Berti <maurizio.berti at gmail.com>
wrote:

> Il giorno dom 20 mar 2022 alle ore 17:13 Matej Brezović <
> matey.brezovic at gmail.com> ha scritto:
>
>> Here is the MRE. If you replace view.verticalHeader() with
>> view.horizontalHeader(), the offset will be visible, but doing it with
>> verticalHeader doesn't seem to affect the table view at all.
>>
>
> I'm actually surprised that it works for the horizontal header for you, as
> it doesn't on my computer. And it shouldn't.
> As written in my previous email, any resize event in the view will always
> trigger updateGeometries() (
> https://doc.qt.io/qt-5/qabstractitemview.html#updateGeometries ), which
> in the case of QTableView potentially updates (or resets) the offset. Since
> widgets *always* receive at least one resize event the first time they are
> shown (especially whenever they are added to layout), your call to
> setOffset() becomes pointless.
>
> The only way to achieve so on startup would be to call self.show() before
> setting the offset (but calling self.show() in the init is usually
> discouraged, while not technically an "error" per se), and/or possibly
> using a single shot QTimer (a 0 interval should theoretically be enough,
> but it might be necessary to increase it).
>
> In any case, there are two problems:
>
> - the offset would be reset again as soon as the view will be resized (due
> any geometry change in any parent widget/layout that could affect it) or
> the scroll bars are used;
> - most importantly, programmatically setting the offset alone is *wrong*,
> as the view uses the offset to compute the visualRect of items, which is
> important for the advanced layout and painting required for item views: the
> result is that, since you're using negative values, the headers will
> actually translate by the given offset, but most items won't be painted at
> all, as their geometry will not be considered valid for the "dirty scroll
> regions" of their indexes; it might be a theoretical bug, but since header
> offsets are *always* positive, I wouldn't consider it as such.
>
> It's not clear what you're trying to achieve, but if your intention is to
> add some "padding" on the top and left of the first row and column, I
> believe that it would be very difficult to do without breaking the default
> behavior.
>
>
> Maurizio
> --
> È difficile avere una convinzione precisa quando si parla delle ragioni
> del cuore. - "Sostiene Pereira", Antonio Tabucchi
> http://www.jidesk.net
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://www.riverbankcomputing.com/pipermail/pyqt/attachments/20220320/e180dcaa/attachment.htm>