[Qt-interest] QGraphicsItem movement problem

[Konstantin Tokarev]

On Thu, 15 Jul 2010 15:00:57 +0200
Riccardo Roasio <riccardo.roasio at gmail.com> wrote: 

> Hi,
> 
> i'm implementing a movement of a QGraphicsItem due to mouse press and
> movement..
> 
>    currentMovement=event->pos().x();
> 
>      if(currentMovement<startMovement)
>      {
>       //movememnt is right to left
>       int delta=startMovement-currentMovement;
>       currentX=startX-delta;
> 
>       std::cout<<"DELTA : "<<delta<<std::endl;
>       std::cout<<"currentX : "<<currentX<<std::endl;
> 
>       setPos(currentX,startY);
>       update();
>      }
> 
> 
> the problem is that the effect is not so fluid, but the continuous
> refresh create a blinking effect of the item..
> 
> I can i solve this problem?

If you still didn't found a solution, I can suggest the next things:
1) pass appropriate QRegion as argument of update - this will update
only changed region of scene. You can construct QRegion as (new are of
object) + (previous area of object)

2) use repaint() instead of update() - it will trigger immediate
repaint, while update() tries to merge several paint events into one

-- 
Regards,
Konstantin