Review Request: Save scrollbar position on plasma exit

[Ignat Semenov]

> On March 13, 2012, 1:12 p.m., Marco Martin wrote:
> > looks good, a thing i would like to be tested is when the saved position is invalid, like either negative or an enormous value.
> > 
> > this shouldn't break it (is even quite probable a value not being valid anymore because there are less files than the previous session)
> 
> Fredrik Höglund wrote:
>     I think it would be a good idea to save the modification time for the folder and use that to check if the saved scrollbar value is likely to be invalid. If the user is able to scroll the view while the layout is in progress, this should also abort restoring the position.
>     
>     Also, I'm wondering if we really need to save the position separately for the iconview and the listview, or if we should use the same key.
>     
>     Otherwise the patch looks good to me.
> 
> Ignat Semenov wrote:
>     Well I've been thinking about separate vs single key and I think separate is easier to read and maintain, less checks and branches.
>     
>     The main problem with a single key would be when the applet is put into a panel, first the icon view gets created and grabs the value, then the list view gets created and gets a 0. Two keys are easier to work with I think.
>     
>     As for scrolling when the layout is in progress, this method is intended to be used at startup only, so the user can not scroll the view. Or do you mean that some dev could use restoreScrollbarPosition() manually after startup?
>     
>     Folder mtime is a nice idea, one more corner case, will try to implement.
> 
> Ignat Semenov wrote:
>     Actually, aborting the automatic scrolling works just fine, as smoothScroll(savedPosition) is used and that one can be interrupted easily.
> 
> Ignat Semenov wrote:
>     OK, as discussed with fredrikh on IRC yesterday, the patch now accounts for multiple layout passes.
>     As far as the dir mtime issue goes, I think that actually falls into the range check case, that is, if the dir content changes, but the number of rows does not, it's probably ok to restore the scroll position. If the number of rows changes, then the scrollbar range changes and that is caught by the check in scrollToSavedPosition(). Same for the list view.
>     
>     Now the only relevant issue is actually aborting the restore if scrolling the view between layout passes in a slow dir.

OK, the only thing left now is to correctly handle this:

applet created on the desktop -> scrolled -> put into the panel ->url changed -> dragged back to the desktop -> scrolled again, but the dir is different and the scroll is invalid

on the other hand, we can't simply discard the value after restoring the position, since if the above is done without changing the url, the scrollbar restore on panel -> desktop is desired and correct.


- Ignat


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On March 16, 2012, 4:31 p.m., Ignat Semenov wrote:
> 
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> This is an automatically generated e-mail. To reply, visit:
> http://git.reviewboard.kde.org/r/104258/
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> 
> (Updated March 16, 2012, 4:31 p.m.)
> 
> 
> Review request for Plasma, Aaron J. Seigo, Marco Martin, and Fredrik Höglund.
> 
> 
> Description
> -------
> 
> This patch implements scrolbar position saving on plasma exit. The change is fairly trivial, however, due to the fact that the view is not populated and layouted immediately simply scrolling to the desired position on creating the view does not work. Instead a signal is emitted on finishing the item layout, when the view has a valid size and the scrollbar has a valid range. The signal is connected to a slot which scrolls the view to the desired position and then disconnects the signal. For the user, a public function in AbstractItemView is introduced, which performs the connection.
> 
> The only problem is that ListView turned out not to have any layout method. It just paints the items one by one, calculating their position on the fly, so I put the signal at the end of updateScrollbar to ensure the scrollbar range is valid. Maybe it should go into the "if (max>0)" branch?
> 
> 
> This addresses bug 261139.
>     http://bugs.kde.org/show_bug.cgi?id=261139
> 
> 
> Diffs
> -----
> 
>   plasma/applets/folderview/abstractitemview.h aa68b90 
>   plasma/applets/folderview/abstractitemview.cpp 3debb70 
>   plasma/applets/folderview/folderview.h 4e441eb 
>   plasma/applets/folderview/folderview.cpp a94ce87 
>   plasma/applets/folderview/iconview.h 12e93b3 
>   plasma/applets/folderview/iconview.cpp 5c4e086 
>   plasma/applets/folderview/listview.cpp 94efe44 
> 
> Diff: http://git.reviewboard.kde.org/r/104258/diff/
> 
> 
> Testing
> -------
> 
> Tested both the icon view and the list view, works fine.
> 
> 
> Thanks,
> 
> Ignat Semenov
> 
>

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