[Interest] QML Custom Scene Graph animation?

Mark markg85 at gmail.com
Tue Jun 4 23:58:35 CEST 2013

On Tue, Jun 4, 2013 at 11:46 PM, Mark <markg85 at gmail.com> wrote:
> On Tue, Jun 4, 2013 at 11:40 PM, Alan Alpert <416365416c at gmail.com> wrote:
>> On Tue, Jun 4, 2013 at 1:51 PM, Mark <markg85 at gmail.com> wrote:
>>> Hi,
>>> I'm playing with custom QML components in Scene Graph. The kind of
>>> component that i want to make is a system monitor like component (and
>>> learning Scene Graph while doing that is a big plus). Now i'm a bit
>>> stuck in the animation area. I can - obviously - just draw a line in
>>> some custom component and then move that component in either x or y
>>> (or both) which will give the same results, but that's not what i'm
>>> looking for.
>>> What i'm looking for is the paintEvent alternative for Scene Graph. I
>>> have "updatePaintNode" re-implemented and am drawing stuff in a
>>> component, but how can i update it when the next frame is requested? I
>>> don't know if i should use a timer, do i? Doesn't Scene Graph work
>>> with vsync and shouldn't i be doing something with that? If so, how?
>> You can call update() on the item to mark the item as needing to call
>> updatePaintNode again in the next frame. If you want to update every
>> single frame then you can call update() inside updatePaintNode(),
>> otherwise you should create a QAbstractAnimation subclass to drive it
>> using the Qt Animation framework.
>> If I recall correctly, this is very similar to QPainter elements
>> except that you can expect the scenegraph to limit updatePaintNode
>> calls to the vsync rate.
>> --
>> Alan Alpert
> Ahhh, just adding update() in updatePaintNode was indeed all i needed.
> I wouldn't have guessed it to be this simple!
> This will likely be enough for now, but if i need more animation
> "power" i will go for your QAbstractAnimation option.
> Thanks a lot Alan :)
> Regards,
> Mark

I do have one issue though. Not big.
When i have an animation running and meanwhile drag my window across
my monitor (in windows 7) then the dragging is all jerky. I don't see
this when i drag a window that is playing a movie or the windows
process monitor..

But i do have that if i play with particles and now with Scene Graph.
Is this a known issue and is there a known workaround for? Or should i
enable (or disable) something?


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