[Qgis-developer] Quick fixes and error communication for ftools

[Bernhard Ströbl]

Am 24.11.2015 um 10:47 schrieb Alessandro Pasotti:
> 2015-11-24 10:42 GMT+01:00 Matthias Kuhn <matthias at opengis.ch
> <mailto:matthias at opengis.ch>>:
>
>     Hi Marco
>
>     Good to have your feedback, you probably know the problem best.
>
>     On 11/24/2015 09:28 AM, Marco Hugentobler wrote:
>>     Hi
>>
>>     >ad issue 1: update fTools to warn users when some features cause
>>     problems
>>     >ad issue 2: quick fix fTools to convert geometry collections to
>>     single geometry types
>>
>>     A function that takes a geometry type and extracts the longest
>>     line / the largest polygon / the first point from the geometry
>>     collection should be straightforward to do.
>
>     Is there no requirement for multi types?
>     Based on what indicator should be chosen what to extract? Try
>     polygons first, if there are none try lines, if there are none take
>     points?
>
>
> Hi,
>
> I've had a quick look to this issue in Las Palmas, the multi-geom issue
> doesn't seem particularly hard to fix,  a possible solution is to keep
> only geometry types of the same (simple or multi) type of the original
> layer, transforming the multi to simple and feeding the original fTools
> with simple geometries.

Hi everybody,

maybe I am misstaken but I doubt it is that easy: If you intersect a 
line and a polygon layer you would expect a line layer as output, If you 
intersect two polygon layers the output could be polygons or lines 
(partially identical boundary) or points (only one identical boundary 
vertex) but you would expect polygons, wouldn't you?
So maybe the rule is: If both input layers are of the same type the 
output layer should be of this type, if both are of different type, 
output should be the lowest input type (low -> high = point -> line -> 
polygon).

Bernhard

>
>>
>>     >These fixes/updates would be made available as fTools updates via
>>     the plugin installer asap
>>
>>     If the fix does not take too long, we probably don't need a
>>     warning at all.
>
>     How much effort (in time) do you think is required to implement this
>     fix?
>
>     Regards,
>     Matthias
>
>
>
> My  quick and dirty estimation is 4-5 days, Python tests included (the
> tests are really not a an option in this case I guess).
>
>
>
> --
> Alessandro Pasotti
> w3: www.itopen.it <http://www.itopen.it>
>
>
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