Review Request: Fixes for screen hotplugging

[Chani Armitage]

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thanks for tackling this :)

there are other situations where the screen # may already be set - when you import a containment, either by starting a stopped activity or some other way. there are a couple of functions for that in libplasma (Corona iirc -load/importLayout?) that would need patching. you'd also have to apply the same logic to anywhere a *desktop* number could remain set, because PDV has the same problem (turn it on, remove a VD, add a VD, no view).

however, I'm thinking that this isn't the best way to solve it - you'd always be looking over your shoulder wondering if you'd missed a way for the screen or desktop # to get set. It might be better to do it the way that (iirc) panel views do it: when desktopcorona checks the screens, it fakes a containmentAdded, and that leads to plasmaapp putting the containment in the view-creation queue.

...or hell, maybe it would make more sense for plasmaapp to just ensure that the views exist as soon as the screen/desktop does, and trust the view and containment to find each other? take a step back and think about what would be most reliable and simple. The codebase for multiscreen/desktop has grown rather organically, and needs a bit of review now :)

- Chani


On 2010-06-24 01:37:15, Anthony Bryant wrote:
> 
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> This is an automatically generated e-mail. To reply, visit:
> http://reviewboard.kde.org/r/4451/
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> 
> (Updated 2010-06-24 01:37:15)
> 
> 
> Review request for Plasma.
> 
> 
> Summary
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> 
> This patch fixes a few problems that occur when hotplugging screens:
> 1. On startup, existing containments are associated with a screen even if that screen does not exist.
>    This causes a bug when a screen is added: since the containment already thinks it is associated with the new screen,
>    it doesn't emit screenChanged() with the new screen, and doesn't get a view created for it.
>    To fix this, I've made Containment::setScreen() set the new screen to -1 if it doesn't exist.
> 2. When a screen is removed, a containment will remain associated with the screen that it is on, causing the same bug
>    as in 1 when the screen is added again.
>    To fix this, I've made sure a containment's screen is set to -1 when its view is removed by PlasmaApp.
> 3. PlasmaApp tries to connect to a nonexistent signal in Kephal: screenAdded(int), the real one is screenAdded(Kephal::Screen*)
> 
> I'm not completely sure that this is the best way of fixing these problems, please correct me if it isn't.
> 
> 
> Diffs
> -----
> 
>   /trunk/KDE/kdebase/workspace/plasma/desktop/shell/plasmaapp.h 1141983 
>   /trunk/KDE/kdebase/workspace/plasma/desktop/shell/plasmaapp.cpp 1141983 
>   /trunk/KDE/kdelibs/plasma/containment.cpp 1141983 
> 
> Diff: http://reviewboard.kde.org/r/4451/diff
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> 
> Testing
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> 
> Started plasma with and without an external screen and tried adding and removing it a few times.
> 
> 
> Thanks,
> 
> Anthony
> 
>

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