[Qgis-developer] QgsRubberBand RuntimeError: underlying C/C++ object has been deleted

Radim Blazek radim.blazek at gmail.com
Wed Feb 12 05:03:33 PST 2014

On Wed, Feb 12, 2014 at 1:45 PM, Radim Blazek <radim.blazek at gmail.com> wrote:
> I am using rubber band in Python plugin:
>   self.rb = QgsRubberBand(self.canvas,  QGis.Polygon)
> and on mouse move
>   self.rb.addPoint( point, update )
> It works well on most systems only for Win7/32bit (QGIS 2.0.1, Python
> 2.7.4) it was reported that it fails with "RuntimeError: underlying
> C/C++ object has been deleted"
> I see that ownership of rubber band is passed to map canvas
>    QgsRubberBand( QgsMapCanvas* mapCanvas /TransferThis/,
> QGis::GeometryType geometryType = QGis::Line );
> that is OK, but QgsMapCanvas should not delete QGraphicsItem until it
> is destructed.
> So how can the QgsRubberBand be deleted before QGIS is closed?

BTW, because true owner of QGraphicsItem is QGraphicsScene, should not
we first mScene->removeItem() (which returns ownership) before item is
deleted in QgsMapCanvas destructor?


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