[QGIS-Developer] Remove all rubberbands from the canvas

Tue Sep 22 09:07:16 PDT 2020

I have eventually worked out the issue.

As I thought the use of .addGeometry() meant I was adding new polygons and the previous ones were not being deleted. This was because the object self.rubberband in my script was not persisting through my code and so I replaced it with an variable defined at a higher level (i.e. rubberbandList = {}) and that allowed me to use the scene().removeItem() successfully.

Hope that is helpful to others.
Paul

From: Paul Wittle
Sent: 22 September 2020 14:52
To: Florian Heyder <Florian.J.Heyder at gmail.com>
Subject: RE: [QGIS-Developer] Remove all rubberbands from the canvas

Hi,

Thanks for the tip; I have indeed tried that and whilst it doesn’t error the rubber band is not removed either.

The scene() object is really odd as well as it is barely in any documentation, I certainly can’t find it in the API reference.

A bit of a mystery really but I suspect I’m accidentally adding the rubber band multiple times and then only removing one of them…but I can’t see why at the moment.

Cheers,
Paul

From: Florian Heyder <Florian.J.Heyder at gmail.com<mailto:Florian.J.Heyder at gmail.com>>
Sent: 22 September 2020 10:59
To: Paul Wittle <P.Wittle at dorsetcc.gov.uk<mailto:P.Wittle at dorsetcc.gov.uk>>
Subject: Re: [QGIS-Developer] Remove all rubberbands from the canvas

Try this, you have to remove from scene:
https://webgeodatavore.github.io/pyqgis-samples/gui-group/QgsRubberBand.html

On Tue, Sep 22, 2020 at 4:01 AM Paul Wittle <paul.wittle at dorsetcouncil.gov.uk<mailto:paul.wittle at dorsetcouncil.gov.uk>> wrote:
Hi,

I’m having an issue with the documentation this morning. I’m writing a small python plugin and adding rubberbands to the canvas which is fine but for some reason I can’t seem to remove them from the canvas at the end.

To start with, this is because I’d not put anything in to remove them but now I’m using the iface.mapCanvas.scene().removeItem() function and they still are present.

I have two questions really:

1.      I can’t see scene defined in the documentation for QgsMapCanvas; is this something that should be there?

2.      Is there a way to simply remove all scenes from the canvas?

Any help would be great 😊
Thanks,

Paul Wittle
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