Thanks. I’m just trying to figure out how this happens because I don’t remove
the layer from the map. It’s actually initially added as an empty layer and
then the geometry is added and then the changes are committed, so I never
remove it. I’ll review my code again to see if I do anything odd.
From: QGIS-Developer <qgis-developer-boun...@lists.osgeo.org> On Behalf Of
Benjamin Jakimow via QGIS-Developer
Sent: Thursday, May 4, 2023 3:21 AM
To: qgis-developer@lists.osgeo.org
Subject: Re: [QGIS-Developer] RuntimeError: wrapped C/C++ object of type
QgsVectorLayer has been deleted
Hi Luke,
to my experience the "RuntimeError: wrapped C/C++ object of type QgsVectorLayer
has been deleted" is raised when the C++ QgsVectorLayer has been deleted by a
parent class.
This is often a QgsMapLayerStore, for example the
QgsProject.instance().mapLayerStore(), from which a layer gets removed when it
is removed from the layer tree.
In that case your self.aoi_layer python reference still exists, but not the
underlying C++ object.
You could ensure that the aoi_layer is not removed from the layer store it is
stored in, for example using QgsLayerStore::takeMapLayer(layer) instead
QgsLayerStore::removeMapLayer(layer).
Or save the aoi_layer_id and test in your eventFilter, if the aoi_layer
instance still exists:
aoi_layer = self.project().mapLayers().get(self.aoi_layer_id)
if isinstance(aoi_layer, QgsMapLayer):
aoi_layer_data_provider = aoi_layer.dataProvider()
...
Greetings,
Benjamin
Am 04.05.2023 um 04:46 schrieb Catania, Luke A ERDC-RDE-GRL-VA CIV via
QGIS-Developer:
I am trying to understand the general meaning of the message below.
RuntimeError: wrapped C/C++ object of type QgsVectorLayer has been deleted
I step through my code in the debugger and at some point my variable,
aoi_layer, is longer assigned to a specific vector layer, though the value
comes back as QgsVectorLayer since I have a watch on it. I though maybe
somehow it got set to “None”, but it’s not None.
I’d like to post code, but I’d have way to much code to post. I am basically
trying to override the map canvas events with an eventFIlter while I go through
a drawing process. I want a particular action to occur when I right click on
the map canvas. I am trying to override the map canvas from completing a
drawing of a shape if the shape is too small, but it does not seem to override
it. The shape is completed when I right click, so it seems like I have not
overridden the event even though I capture the event using the code below:
def eventFilter(self, source, event):
if event.type() == QEvent.MouseButtonPress and event.button() ==
Qt.RightButton:
if self.valid_size(self.aoi_area):
aoi_layer_data_provider =
self.aoi_layer.dataProvider()
self.aoi_feature.setGeometry(self.aoi_geometry)
aoi_layer_data_provider.addFeatures([self.aoi_feature])
self.aoi_layer.commitChanges()
self.aoi_layer.setExtent(self.aoi_feature.geometry().boundingBox())
self.add_area_perimeter()
self._refresh_and_zoom_to_layer(True)
self.AOI_SIZE_VALIDATOR_LABEL.close()
self.track_cursor = False
iface.mapCanvas().viewport().removeEventFilter(self)
Return False
I initially had the return to be “return super().eventFilter(source, event)”
So the shape is completed and it adds it to the layer that is open for editing.
My function allows the drawing to continue because my check indicates the
shape is not large enough so the commit should not happen unless the size is
valid.
I can continue drawing but I right click on the map canvas it completes the
drawing a second time, so now I have two rectangles, both with the same start
position, but one larger than the other. It is when I create a second layer to
draw that I get the runtime error.
So I have two problems. I don’t seem to be completely overriding the build in
event handler and QGIS is still completing the drawing when I right click. And
somehow this may be contributing to the runtime error.
If I can understand in general how my object is deleted when I don’t have any
statement that deletes the object maybe I can figure it out the second issue.
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Dr. Benjamin Jakimow
Earth Observation Lab | Geography Department | Humboldt-Universität zu Berlin
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