Improvements for view positioning when scrolling

[karlch]

Adds a new setting scroll_to_center that controls whether the view is always centred when scrolling along with the :move-view command that can position the view at top / center / bottom with the zt / zz / zb keybindings.

[jcjgraf]

zt, zz and tb work as expected.

The scroll_to_center option does not seem to have an impact for me (I tried to set it dynamically using :set scroll_to_center XXX). No matter that I set the option to, the view is never centered.

This is probably, because in widget::scrollTo, hint is not as expected None, but ScrollHint.EnsureVisible.

On top of that, I was able to observe two crashes.
I changed the scroll_to_cente option dynamically, and afterwards I scrolled in the thumbnail view:

[10:58:31] ERROR    <vimiv>              Uncaught exception! Exiting gracefully and printing stack...
Traceback (most recent call last):
  File "/home/jeanclaude/Documents/Programming/vimiv-qt/vimiv/gui/thumbnail.py", line 458, in resizeEvent
    self.scrollTo(self.currentIndex())
  File "/home/jeanclaude/Documents/Programming/vimiv-qt/vimiv/widgets.py", line 35, in scrollTo

[10:59:56] ERROR    <vimiv>              Uncaught exception! Exiting gracefully and printing stack...
  Traceback (most recent call last):
  File "/home/jeanclaude/Documents/Programming/vimiv-qt/vimiv/gui/thumbnail.py", line 458, in resizeEvent
    self.scrollTo(self.currentIndex())
  File "/home/jeanclaude/Documents/Programming/vimiv-qt/vimiv/widgets.py", line 35, in scrollTo
    super().scrollTo(index, hint)
TypeError: scrollTo(self, index: QModelIndex, hint: QAbstractItemView.ScrollHint = QAbstractItemView.EnsureVisible): argument 2 has unexpected type 'NoneType'

I hope this helps. I do not have time to look into the code atm. But let me know if you need anything else.

Btw, I like the option of having a not-centered view a lot (thanks for the idea @Markuzcha and the implementation @karlch) 😊

[karlch]

Thanks @jcjgraf for testing this so quickly! I can reproduce both, hopefully I find the time this afternoon for a detailed investigation 😊

EDIT: Quick fix seems to fix the setting, but I have weird issues with zz / zt / zb now, needs more investigation later.

[karlch]

@jcjgraf mind giving this another shot? I am no longer able to reproduce any issues with zt / zz / zb I had, unsure if there were unstaged changes or I messed up somehow 😕

[Markuzcha]

I just gave it a shot @karlch - It works like a charm !
Bot zz / zt / zb and the scroll_to_center setting, without crashes or error messages in the command line whatsoever

Thank you very much, it's even more pleasure to use it now.

(PD.: Would be great to have it updated in the AUR as well.)

[jcjgraf]

@karlch Everything works as expected 🎉

@Markuzcha It is in the AUR git package as soon as this is merged, and in the general AUR package, once a new version of vimiv gets released.

[karlch]

Awesome, thanks to both of you for testing! 😊

As @jcjgraf mentioned, the changes are now available via the AUR git package.