[Qt] Animation - Big CPU consumption - maemo.org

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Figa	2010-04-22 , 14:02
Posts: 270 \| Thanked: 239 times \| Joined on Dec 2009 @ Czech Republic	#1

Please look at this code:

Code:

 QPropertyAnimation *animation = new QPropertyAnimation(item, "pos");
		 animation->setDuration(199);
		 animation->setStartValue(QPointF(20,20));
		 animation->setEndValue(QPointF(20,40));
		 animation->start();

I have this code in function. This function is called every 200ms. It takes out about 90% CPU. What is wrong? Thx for your replies.

Last edited by Figa; 2010-04-22 at 14:38.

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attila77	2010-04-22 , 14:24
Posts: 3,319 \| Thanked: 5,610 times \| Joined on Aug 2008 @ Finland	#2

Are you sure about the 200ms ? That's like 5 steps in a second. IIRC The default should be around 40-50ms (so you get 25+ fps).

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Figa	2010-04-22 , 14:32
Posts: 270 \| Thanked: 239 times \| Joined on Dec 2009 @ Czech Republic	#3

Yes I am sure. It is in QTimer and I start it as timer->start(200);

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Rob1n	2010-04-22 , 14:35
Posts: 3,617 \| Thanked: 2,412 times \| Joined on Nov 2009 @ Cambridge, UK	#4

So, every 200ms you're creating a new animation that runs for 300ms?

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timoph	2010-04-22 , 14:37
Posts: 415 \| Thanked: 732 times \| Joined on Jan 2009 @ Finland	#5

If I understood that function correctly you are moving some item 20 pixels down 5 times a second. Or do you use it to move different items?

Anyway it looks like you are creating a new QPropertyAnimation object 5 times a second. You could create the object elsewhere (e.g. as a class member) and use it's pointer in the function.

On a side note, the animation duration is longer than the interval of the function calls.

Hard to give any other comments without more details about the purpose of the function and you application.

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Figa	2010-04-22 , 14:38
Posts: 270 \| Thanked: 239 times \| Joined on Dec 2009 @ Czech Republic	#6

Sry bad example time is changeable. Duration is 199ms.

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timoph	2010-04-22 , 14:44
Posts: 415 \| Thanked: 732 times \| Joined on Jan 2009 @ Finland	#7

You don't need a QTimer to do an infinite loop for QPropertyAnimation.

Just create the animation once and set

Code:

animation->setLoopCount(-1);

http://doc.qt.nokia.com/4.6/qabstrac...loopCount-prop

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Figa	2010-04-22 , 18:06
Posts: 270 \| Thanked: 239 times \| Joined on Dec 2009 @ Czech Republic	#8

thx, i have timer because i need timer for other action. ok i will try it when i will come to home. i am not sure if it will work because i need to change parameters of animation

Last edited by Figa; 2010-04-22 at 18:08.