[QGIS-Developer] pyqgis QgsGeometrySnapper does not snap to a source created inside a function

[Gabriel De Luca]

Hi German,

  Thanks. Yes, it works that way. Do you know why?


Regards,
Gabriel

El jue, 19 oct 2023 a la(s) 13:04, Germán Carrillo (
carrillo.german at gmail.com) escribió:

> Hi Gabriel,
>
> Does the result change if you first create a Python variable for storing
> your new layer?
> I mean:
>
>
> *referenceSource = create_scratch_reference_layer()*
> *snapper = QgsGeometrySnapper(referenceSource)*
>
> instead of:
>
> *snapper = QgsGeometrySnapper(*
> *    referenceSource=create_scratch_reference_layer()*
> *)*
>
> Regards,
>
> Germán
>
>
> El jue, 19 oct 2023 a las 14:46, Gabriel De Luca via QGIS-Developer (<
> qgis-developer at lists.osgeo.org>) escribió:
>
>> Hello all,
>>
>>   I am working with the QgsGeometrySnapper pyqgis class, and have a
>> problem to snap to a reference layer which is created inside a function
>> (and returned by it).
>>
>>   The code shared at [1] prints:
>>
>> result = <QgsGeometry: Polygon ((0.10000000000000001
>> -0.10000000000000001, 10.09999999999999964 0, 9.90000000000000036
>> 10.09999999999999964, 0 10, 0.10000000000000001 -0.10000000000000001))>
>>
>>   Which means that the geomPolygon was not snapped to the reference layer.
>>   But, if uncomment the line 41, which adds the reference layer to the
>> project, the code prints:
>>
>> result = <QgsGeometry: Polygon ((0 0, 10 0, 10 10, 0 10, 0 0))>
>>
>>   So, for some reason, adding the reference layer to the project makes
>> the snapper to work.
>>
>>   I want to ask you if you know why is this happening. Maybe I need to
>> add something to make it work consistently.
>>
>>
>> Regards,
>> Gabriel
>>
>> [1] https://pastebin.com/raw/Y9v51ZMq
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