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List: amarok-devel
Subject: Re: Review Request: Use QGraphicsScene::NoIndex instead of
From: "Mark Kretschmann" <kretschmann () kde ! org>
Date: 2011-07-24 15:21:50
Message-ID: 20110724152150.17622.84092 () vidsolbach ! de
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Ship it!
This sounds like a very sane change to me.
- Mark
On July 16, 2011, 12:41 p.m., Daniel Faust wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://git.reviewboard.kde.org/r/101966/
> -----------------------------------------------------------
>
> (Updated July 16, 2011, 12:41 p.m.)
>
>
> Review request for Amarok.
>
>
> Summary
> -------
>
> As currently discussed in the amarok mailing list \
> (http://mail.kde.org/pipermail/amarok/2011-July/032753.html) and in many bug \
> reports, there's a Qt bug (http://bugreports.qt.nokia.com/browse/QTBUG-18021) that \
> can lead to random crashes. If I got this right, it seems to be the second time \
> that there's bug in Qt in the BspTreeIndex. So a simple solution would be to just \
> disable the index.
>
> This addresses bugs 207382 and 269227.
> https://bugs.kde.org/show_bug.cgi?id=207382
> https://bugs.kde.org/show_bug.cgi?id=269227
>
>
> Diffs
> -----
>
> src/context/ContextView.cpp e90c262
>
> Diff: http://git.reviewboard.kde.org/r/101966/diff
>
>
> Testing
> -------
>
> I'm using amarok this way for some weeks now and I couldn't see any downsides.
> I haven't made a speed test but it feels equally fast.
> Furthermore I don't know much about this, but according to the Qt documentation it \
> doesn't seem that amarok would benefit much from this index since a lot of \
> GraphicsObjects are created dynamically.
> QGraphicsScene::BspTreeIndex:
> A Binary Space Partitioning tree is applied. All QGraphicsScene's item location \
> algorithms are of an order close to logarithmic complexity, by making use of binary \
> search. Adding, moving and removing items is logarithmic. This approach is best for \
> static scenes (i.e., scenes where most items do not move). QGraphicsScene::NoIndex:
> No index is applied. Item location is of linear complexity, as all items on the \
> scene are searched. Adding, moving and removing items, however, is done in constant \
> time. This approach is ideal for dynamic scenes, where many items are added, moved \
> or removed continuously.
>
> Thanks,
>
> Daniel
>
>
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This is an automatically generated e-mail. To reply, visit:
<a href="http://git.reviewboard.kde.org/r/101966/">http://git.reviewboard.kde.org/r/101966/</a>
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<p>Ship it!</p>
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">This sounds like a very \
sane change to me.</pre> <br />
<p>- Mark</p>
<br />
<p>On July 16th, 2011, 12:41 p.m., Daniel Faust wrote:</p>
<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="8" \
style="background-image: \
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<div>Review request for Amarok.</div>
<div>By Daniel Faust.</div>
<p style="color: grey;"><i>Updated July 16, 2011, 12:41 p.m.</i></p>
<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;">As currently discussed in the amarok mailing list \
(http://mail.kde.org/pipermail/amarok/2011-July/032753.html) and in many bug reports, \
there's a Qt bug (http://bugreports.qt.nokia.com/browse/QTBUG-18021) that can \
lead to random crashes. If I got this right, it seems to be the second time that \
there's bug in Qt in the BspTreeIndex. So a simple solution would be to just \
disable the index.</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;">I'm using amarok this way for some weeks now and I couldn't see \
any downsides. I haven't made a speed test but it feels equally fast.
Furthermore I don't know much about this, but according to the Qt documentation \
it doesn't seem that amarok would benefit much from this index since a lot of \
GraphicsObjects are created dynamically.
QGraphicsScene::BspTreeIndex:
A Binary Space Partitioning tree is applied. All QGraphicsScene's item location \
algorithms are of an order close to logarithmic complexity, by making use of binary \
search. Adding, moving and removing items is logarithmic. This approach is best for \
static scenes (i.e., scenes where most items do not move). QGraphicsScene::NoIndex:
No index is applied. Item location is of linear complexity, as all items on the scene \
are searched. Adding, moving and removing items, however, is done in constant time. \
This approach is ideal for dynamic scenes, where many items are added, moved or \
removed continuously.</pre> </td>
</tr>
</table>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Bugs: </b>
<a href="https://bugs.kde.org/show_bug.cgi?id=207382">207382</a>,
<a href="https://bugs.kde.org/show_bug.cgi?id=269227">269227</a>
</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">
<li>src/context/ContextView.cpp <span style="color: grey">(e90c262)</span></li>
</ul>
<p><a href="http://git.reviewboard.kde.org/r/101966/diff/" style="margin-left: \
3em;">View Diff</a></p>
</td>
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