[vtkusers] Dealing with QTBUG-40889

[Elvis Stansvik]

2016-07-01 15:07 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> I'm in the unfortunate situation of having to support Qt 5.5.1, and I'm
> hit by
>
>     https://bugreports.qt.io/browse/QTBUG-40889
>
> which was fixed in 5.6 with
>
>     https://codereview.qt-project.org/#/c/126136/
>
> I've been trying to find a way to work around this bug using a combination
> of native and non-native event filters in Qt, but haven't really found a
> good solution.
>
> The problem is I want to use the built-in interactor styles in VTK, such
> as vtkInteractorStyleTrackballCamera, and these makes calls to Render() as
> fast as the mouse events arrive.
>
> I have to ask: Is this really a good idea, shoudn't the rendering be
> governed by a timer during the interaction (say dolly), to be more robust
> against a flood of mouse events? The reason Qt has even buffered events
> (and hence opened up for compression, barring that bug) is that the main
> thread is overworked. And this is due to VTK rendering at every mouse move
> event.
>
> If I make my own completely custom interactor style, I of course have full
> control and can let a timer govern the rendering, but I was hoping to
> leverage the built-in ones. And it's not possible to subclass them and
> disable just the Render calls unfortunately.
>
> At the moment I don't quite know what to do. Moving the camera around in a
> VTK window is like syrup, and our product is to run using the Qt 5.5.1 that
> is packaged in *buntu Xenial :(
>
> Thanks for any advice, especially if you've worked around this problem
> yourself somehow.
>

I was thinking: Surely ParaView (when compiled against Qt 5.5.x) must be
facing this problem as well? I'm sure the ParaView folks would like this
combo to work well, since Ubuntu 16.04 is an LTS release that will see very
widespread use. Any ParaView developers who could speak up?

Elvis


> Elvis
>
>
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