[QGIS-Developer] Split parts tool - invalid output

Bernhard Ströbl bernhard.stroebl at jena.de
Tue Jun 20 05:58:26 PDT 2017

Hi Giovanni

Am 20.06.2017 um 14:18 schrieb Giovanni Manghi:
> Hi,
>> Hi,
>> I would like to raise attention for an issue which was discussed in
>> length in the qgis-users list [1]
>> You can ignore the beginning of the discussion where I mixed up "Split
>> parts" and "Split features".
>> The split features tool does not produce valid geometries. This can be
>> easily reproduced by splitting one part of a multipart feature and
>> then try to split that part again (or save and check the feature with
>> e.g. postgis' st_isvalid()). This goes hand-in-hand with the comments
>> in a related, older issue [2].
>> This makes the workflow much more complex [see 3], if you want to have
>> a valid output at the end.
>> The discussion ended in a new Tool in the DigitizingTools (0.11.0)
>> plugin (thank you Bernhard), which acts much more intuitive from a
>> users' perspective.
>> - singlepart features are split and one half inserted as a new feature
>> - multipart features are split and the user has to choose which part
>> gets inserted as a new feature, while the other half stays a multipart
>> feature with all other parts still connected
>> This raises the question if and how to get that to replace the core tools.
>> Happy for any input :)
> is strange this thread is seemingly not getting much traction at least
> in the dev list. Having a core digitizing tool that cripples
> geometries do not look good to me, and apparently a good solution has
> been implemented (or had to) in a plugin. Isn't worth having core
> doing it the right way?
> cheers
> -- G --

I would definitely wish to have proper tools in core but as I am not a 
C++ guy all I can do is implement things in a Python plugin :-( 
DigitizingTools is an effort to provide missing tools until there is a 
solution in core (I just abandoned a tool whose functionality has been 
implemented). I welcome any C++ dev going ahead and copying (and 
improving) the tools I provide.
You may have seen that I commented on [1]


[1] https://issues.qgis.org/issues/12754

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