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<base href="https://bugs.documentfoundation.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_UNCONFIRMED "
title="UNCONFIRMED - The while loop for Javascript presentation engine"
href="https://bugs.documentfoundation.org/show_bug.cgi?id=107561">107561</a>
</td>
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<th>Summary</th>
<td>The while loop for Javascript presentation engine
</td>
</tr>
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<th>Product</th>
<td>LibreOffice
</td>
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<th>Version</th>
<td>5.3.2.2 release
</td>
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<th>Hardware</th>
<td>All
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>UNCONFIRMED
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
</td>
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<th>Component</th>
<td>Impress
</td>
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<th>Assignee</th>
<td>libreoffice-bugs@lists.freedesktop.org
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<th>Reporter</th>
<td>wanliyou@gmail.com
</td>
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<pre>Description:
Seems like exported JS presentation engine is directly generated from cpp
version, here:
<a href="https://github.com/LibreOffice/core/blob/2eae33e82e5f91d6dbaf7e8e848f53644596059d/slideshow/source/engine/slideshowimpl.cxx#L2370">https://github.com/LibreOffice/core/blob/2eae33e82e5f91d6dbaf7e8e848f53644596059d/slideshow/source/engine/slideshowimpl.cxx#L2370</a>
The generated JS looks like this:
FrameSynchronization.prototype.synchronize = function()
{
if( this.bIsActive )
{
while( this.aTimer.getElapsedTime() < this.nNextFrameTargetTime )
;
}
this.markCurrentFrame();
}
The while loop will be CPU hogging and make the UI no response, so I think this
kind of code should be optimized to schedule in a Timer/requestAnimationFrame.
FrameSynchronization.prototype.synchronize = function()
{
if ( this.bIsActive && ( this.aTimer.getElapsedTime() <
this.nNextFrameTargetTime )) {
setTimeout(this.synchronize.bind(this), 16);
}
else {
this.markCurrentFrame();
}
}
Steps to Reproduce:
1. Open a slide with long time animations
2.
3.
Actual Results:
CPU hogging and janky animation
Expected Results:
Smooth animation and use much lesser CPU cycles.
Reproducible: Always
User Profile Reset: No
Additional Info:
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_0) AppleWebKit/537.36
(KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36</pre>
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