[Qt-interest] QGraphicsView QThread

[Bas Terwijn]

hi all,

Fred Duarte wrote:
> I have not tried this approach(Graphics update with QThreads), but seems a
> cool solution. Do you have this code published anywhere?
In the small attachment you find two project:

GraphicsSceneTimer, which uses QTimer and works fine
GraphicsSceneThread, which uses QThread and sometimes fails to update 
and crashes regularly

> And for the problem you're having, it may require a more detailed
> thread safety mechanism. Not just a mutex in the update() method.
>
This approach worked when using a simple QWidget to draw to. I am open 
to suggestions. I already tried many things without success.

kind regards,
Bas Terwijn

> -- 
> Frederico Duarte
>
> On Mon, Mar 30, 2009 at 12:03 PM, Bas Terwijn <B.Terwijn at uva.nl 
> <mailto:B.Terwijn at uva.nl>> wrote:
>
>
>     hi all,
>
>     I am trying for some time to use QGraphicsView in a multi-threaded
>     application where in the main thread I create an QGraphicsView object
>     and run the event loop while in a seperate QThread I create and and
>     change many QGraphicsItems that are to be visualized in the main
>     thread.
>     For thread safety I use a mutex to synchronize the (overloaded)
>     QGraphicsView::update() method and all changes to the QGraphicsItems.
>
>     My approach doesn't work. I find that the QGraphicsView doesn't
>     update,
>     even when I send signals which I think should start the
>     QGraphicsView::updateScene() from the main thread. I also experience
>     core dumps.
>
>     Did anybody find a way to use QGraphicsView to visualize
>     QGraphicsItems
>     that are changed by a seperate QThread?
>
>     Thank you for your time,
>     Bas Terwijn
>
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