[PyQt] QGraphicsView rubberband selection

[Antonio Valentino]

Hi Alexander,

Il giorno Thu, 29 Oct 2009 16:53:04 +0100
Alexander Borghgraef <alexander.borghgraef.rma at gmail.com> ha scritto:

> Hi all,
> 
> 
>  I've been writing an app which displays sequences of images, and
> allows for the selection of regions of interest in them.
> Display/playback works like a charm, basically I use a
> QGraphicsScene/View setup with a QGraphicsPixmapItem in the scene,
> which is then updated upon receiving the timeout signal of a timer.
> Pretty basic stuff.
> 
>  Now for selection: one approach would be to subclass either the
> QGraphicsView or the QGraphicsPixmapItem, overload the mouse
> events, get the selection coordinates from that for further use and
> put a QGraphicsRectItem on the scene on top of the selection.

Yes, one solution is subclassing, another could be using
eventFilter(s).

> Now, I noticed that QGraphicsView already has rubberband selection
> implemented: when I set the View's DragMode to
> QGraphicsView.RubberBandDrag, I get a nice rubberband rectangle when
> I drag the mouse across the View. My problem here is
> that I can't seem to figure out how to access the selection
> coordinates of that rectangle. Is there some way of accessing this
> data? There doesn't seem to be any getDragSelection( ) or some such
> function, but then how does this work? Do I need to get it from the
> underlying QGraphicsScene object? Help would be appreciated.

I have the same problem. At the moment I have a solution based on
event filters but I'm very interested in a solution exploiting built-in
features so please keep updated.


Best regards

-- 
Antonio Valentino