[Qt-interest] translate vs setPos

[Oliver.Knoll at comit.ch]

On 2010-11-30 Brian Brian McKinnon wrote:

> Hi everyone,
> 
> I'm having some trouble with creating objects and setting there 
> position.  I use the code below to create an object after the completion of a drag operation.
> 
> DragableRectangleItem::DragableRectangleItem(const QPointF & pos, ...);
> ....
>     //setPos(pos.x(), pos.y());    // <- Doesn't work
>     //moveBy(pos.x(), pos.y());    // <- Doesn't work
>     //translate(pos.x(), pos.y()); // <- Works } At the bottom I have 

> The problem is that once I click and move the item positioned with 
> setPos or moveBy it jumps back to the origin of the rect completely 

Well, where does the parameter 'pos' come from? From the mouse event->pos()? Note that this will give you the *parent* mouse coordinate, so (I assume, did not verify) for a mouse event in a QGraphicsScene the parent would be the underlying item! So you probably want to initialize the parameter 'pos' with something like event->scenePos(), such that you get the global scene coordinates instead (because that is where the user would expect the item to be placed ;)

Does that help?

Cheers, Oliver
--
Oliver Knoll
Dipl. Informatik-Ing. ETH
COMIT AG - ++41 79 520 95 22