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List:       kde-devel
Subject:    Re: Loading and "unloading" a shared library after use
From:       Albert Astals Cid <aacid () kde ! org>
Date:       2014-04-21 21:27:06
Message-ID: 3036057.cmRC8QFDol () xps
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El Dilluns, 21 d'abril de 2014, a les 20:49:06, Shantanu Tushar Jha va 
escriure:
> Hi fellow devs,
> 
> In the latest Kubuntu release, 14.04, Plasma Media Center's primary feature
> - playback of audio and video has stopped working. This is because we link
> to libplasma which in turn links to libgstreamer-1.0 while QtMultimediaKit
> links to libgstreamer-0.10. This upsets Glib because it doesn't want the
> same binary load both gstreamer-1.0 and gstreamer-0.10[1]
> 
> Now, we use (and link to) Plasma for two things-
> 
> - Setting the Oxygen theme -
> Plasma::Theme::defaultTheme()->setThemeName("oxygen")
> - Load PMC's main QML file and images which are part of a Plasma::Package
> 
> Removing these two from the code, and removing the link to libplasma, we
> can get PMC to play stuff fine. However, this means we 1. use the Air theme
> which doesn't really look very nice[2] and 2. we need to figure out another
> way to locate the installed QML files. The latter is workable, but we
> really want to be able to use Oxygen Plasma theme.
> 
> We do both these things when the app starts, so I am wondering if there is
> a way we could dynamically load libplasma, make these two method calls, and
> somehow "unload" libplasma. I have two questions -
> 
> 
> - Does that ^ even make sense? Will it solve the problem?
> - If yes, how exactly do you do it?

You can use QLibrary to load/unload libraries (basically a wrapper around 
dlopen and friends). I have no idea what will happen if you still hold objects 
created by those libraries in memory though (since i guess you'll need that 
for PMC), my guess would be crashing :-/

I would suggest helping with the port of QtMultimediaKit to gestreamer-1.0, i 
know that doesn't immediately help your users though :-/

Cheers,
  Albert

> 
> Help appreciated, so that our users can play their audio and video again ;)
> 
> Cheers,
> [1]
> http://cgit.freedesktop.org/gstreamer/gstreamer/tree/docs/random/porting-to-> \
> 1.0.txtsection "Troubleshooting" [2] http://i.imgur.com/0k1TTwW.png


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