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List:       kfm-devel
Subject:    Re: Review Request 117021: Fix Bug 332159 - dolphin does not remember scroll position when going bac
From:       "Emmanuel Pescosta" <emmanuelpescosta099 () gmail ! com>
Date:       2014-04-04 13:08:45
Message-ID: 20140404130845.31792.70401 () probe ! kde ! org
[Download RAW message or body]

> On March 24, 2014, 11:45 p.m., Frank Reininghaus wrote:
> > Thanks for your analysis and your patch! You are right, the double emission of \
> > KFileItemModel's directoryLoadingCompleted() signal is the problem. 
> > Modifying DolphinView::updateViewState() such that it still keeps the position to restore \
> > if the restoration was not successful looks like a good approach to fix the problem! The \
> > second call of that function will restore the correct position then. However, I'm not \
> > really sure why 
> > KFileItemModel::setShowHiddenFiles(bool show)
> > 
> > calls slotCompleted() at all (this is what triggers the emission of \
> > directoryLoadingCompleted() eventually). Removing that call also fixes the problem for me, \
> > but it will probably cause some regressions? There is probably a reason why the call is \
> > there, but it seems that the first commit that "git blame" points to simply changed the \
> > indentation of that line. Some more code archeology might be needed. But maybe you had \
> > already tried this approach and found that the change in DolphinView is better? 
> > The reason why I'm asking is that I see a certain risk that the change in DolphinView will \
> > cause subtle bugs in the future. Imagine the following scenario: 
> > 1. In folderA/, scroll down and click the very last folder (in Details View).
> > 
> > 2. While in folderA/subfolder/, remove any other subfolder in folderA from a terminal.
> > 
> > 3. Go "back". Restoring the position will fail because the view's total height is smaller \
> > than it used to be. However, with your patch, the desired position will still be stored in \
> > m_restoredContentsPosition, right? 
> > 4. Go to any other folder, which has more items than folderA/. If I'm not mistaken, the \
> > view might now scroll down to the offset which should originally have been restored in step \
> > 3. 
> > This reminds me a bit of https://bugs.kde.org/show_bug.cgi?id=329377, which was not exactly \
> > easy to debug. But I'm not completely sure if my analysis is right, and the same problem \
> > could indeed happen in the "restore scroll position" context.

> Removing that call also fixes the problem for me, but it will probably cause some \
> regressions?
I don't know if it will cause any regressions, this is why I have fixed it in \
DolphinView::updateViewState() so  that all slotCompleted() calls try to scroll to the right \
position.

> subtle bugs in the future
No problems found so far. 

I think we should fix it by removing the slotCompleted() call in setShowHiddenFiles, because it \
is a much nicer solution and if we get some regression bug reports (I doubt that ;) we can \
revert it and apply this patch.  What do you think?

Thanks!


- Emmanuel


-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/117021/#review54044
-----------------------------------------------------------


On March 24, 2014, 4:19 p.m., Emmanuel Pescosta wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/117021/
> -----------------------------------------------------------
> 
> (Updated March 24, 2014, 4:19 p.m.)
> 
> 
> Review request for Dolphin.
> 
> 
> Bugs: 332159
> http://bugs.kde.org/show_bug.cgi?id=332159
> 
> 
> Repository: kde-baseapps
> 
> 
> Description
> -------
> 
> Fix Bug 332159 - dolphin does not remember scroll position when going back
> 
> DolphinView::updateViewState will be called multiple times in some special cases,
> so we only reset the restored contents position if we have successfully reached it.
> 
> 
> Diffs
> -----
> 
> dolphin/src/views/dolphinview.cpp 2769d67 
> 
> Diff: https://git.reviewboard.kde.org/r/117021/diff/
> 
> 
> Testing
> -------
> 
> Works. 
> 
> See Ashish's comment #5 in the bug report:
> 
> Ashish 2014-03-23 19:02:46 CET
> I can reproduce this only when the 1st folder has "Show hidden files" enabled. 
> Step 1: Enable Show Hideen Files in say, home folder. 
> 2: Scroll down, open any folder. 
> 3: click back. We reach the top position in home folder. When Hidden files is not enabled, \
> clicking on back remembers the scroll position.  Version tested: 4.12.3 on Ubuntu 13.10
> 
> 
> Thanks,
> 
> Emmanuel Pescosta
> 
> 


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<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: 10px;">
 <p style="margin-top: 0;">On March 24th, 2014, 11:45 p.m. CET, <b>Frank Reininghaus</b> \
wrote:</p>  <blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;">  <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; \
white-space: -o-pre-wrap; word-wrap: break-word;">Thanks for your analysis and your patch! You \
are right, the double emission of KFileItemModel&#39;s directoryLoadingCompleted() signal is \
the problem.

Modifying DolphinView::updateViewState() such that it still keeps the position to restore if \
the restoration was not successful looks like a good approach to fix the problem! The second \
call of that function will restore the correct position then. However, I&#39;m not really sure \
why

KFileItemModel::setShowHiddenFiles(bool show)

calls slotCompleted() at all (this is what triggers the emission of directoryLoadingCompleted() \
eventually). Removing that call also fixes the problem for me, but it will probably cause some \
regressions? There is probably a reason why the call is there, but it seems that the first \
commit that &quot;git blame&quot; points to simply changed the indentation of that line. Some \
more code archeology might be needed. But maybe you had already tried this approach and found \
that the change in DolphinView is better?

The reason why I&#39;m asking is that I see a certain risk that the change in DolphinView will \
cause subtle bugs in the future. Imagine the following scenario:

1. In folderA/, scroll down and click the very last folder (in Details View).

2. While in folderA/subfolder/, remove any other subfolder in folderA from a terminal.

3. Go &quot;back&quot;. Restoring the position will fail because the view&#39;s total height is \
smaller than it used to be. However, with your patch, the desired position will still be stored \
in m_restoredContentsPosition, right?

4. Go to any other folder, which has more items than folderA/. If I&#39;m not mistaken, the \
view might now scroll down to the offset which should originally have been restored in step 3.

This reminds me a bit of https://bugs.kde.org/show_bug.cgi?id=329377, which was not exactly \
easy to debug. But I&#39;m not completely sure if my analysis is right, and the same problem \
could indeed happen in the &quot;restore scroll position&quot; context.</pre>  </blockquote>







</blockquote>

<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; \
white-space: -o-pre-wrap; word-wrap: break-word;">&gt; Removing that call also fixes the \
problem for me, but it will probably cause some regressions? I don&#39;t know if it will cause \
any regressions, this is why I have fixed it in DolphinView::updateViewState() so  that all \
slotCompleted() calls try to scroll to the right position.

&gt; subtle bugs in the future
No problems found so far. 

I think we should fix it by removing the slotCompleted() call in setShowHiddenFiles, because it \
is a much nicer solution and if we get some regression bug reports (I doubt that ;) we can \
revert it and apply this patch.  What do you think?

Thanks!</pre>
<br />










<p>- Emmanuel</p>


<br />
<p>On March 24th, 2014, 4:19 p.m. CET, Emmanuel Pescosta wrote:</p>








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<div>Review request for Dolphin.</div>
<div>By Emmanuel Pescosta.</div>


<p style="color: grey;"><i>Updated March 24, 2014, 4:19 p.m.</i></p>







<div style="margin-top: 1.5em;">
 <b style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Bugs: </b>


 <a href="http://bugs.kde.org/show_bug.cgi?id=332159">332159</a>


</div>



<div style="margin-top: 1.5em;">
 <b style="color: #575012; font-size: 10pt;">Repository: </b>
kde-baseapps
</div>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
 <table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: 1px \
solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; \
white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">Fix Bug 332159 - \
dolphin does not remember scroll position when going back

DolphinView::updateViewState will be called multiple times in some special cases,
so we only reset the restored contents position if we have successfully reached it.
</pre>
  </td>
 </tr>
</table>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: 1px solid \
#b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; \
white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">Works. 

See Ashish&#39;s comment #5 in the bug report:

 Ashish 2014-03-23 19:02:46 CET
I can reproduce this only when the 1st folder has &quot;Show hidden files&quot; enabled. 
Step 1: Enable Show Hideen Files in say, home folder. 
2: Scroll down, open any folder. 
3: click back. We reach the top position in home folder. When Hidden files is not enabled, \
clicking on back remembers the scroll position.  Version tested: 4.12.3 on Ubuntu 13.10</pre>
  </td>
 </tr>
</table>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">

 <li>dolphin/src/views/dolphinview.cpp <span style="color: grey">(2769d67)</span></li>

</ul>

<p><a href="https://git.reviewboard.kde.org/r/117021/diff/" style="margin-left: 3em;">View \
Diff</a></p>







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