[Qgis-developer] Labels on topologically wrong polygons

[Larry Shaffer]

Hi Paolo,

On Wed, Jul 24, 2013 at 9:07 AM, Paolo Cavallini <cavallini at faunalia.it>wrote:

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> Hi all.
> I noticed that labels are not placed on topologically wrong polygons. This
> makes
> sense, but is surprising for the user: could we think of some solution?
>

I think QGIS should offer the option to on-the-fly try to fix those
geometries. This was discussed previously [0], and I think the best
solution presented so far is to find a way to incorporate the standalone
PostGIS library 'lwgeom' into the QGIS source tree, or just the relevant
bits, as Juergen suggested at the end of that thread, and add support in
QgsGeometry.

As a side note, Spatialite 4.x includes support for the lwgeom library as
well, and for the Mac 'homebrew' package manager, which offers an install
of QGIS, it causes a circular dependency issue[1]. The solution there was
to disable the lwgeom support in Spatialite. Currently, other software that
uses the lwgeom lib (I think) also require that PostGIS/PostgreSQL already
be installed.

Ideally, if someone where to find a way (maybe it is simple, but not for
me) to have the lwgeom library compile-able as a standalone library, apart
from PostGIS, it would help both the QGIS project and some packaging issues
now and down the road. I suppose we could ask Paul Ramsey or Sandro
Santilli what they think about such an idea, and if they could help.

[0]
http://osgeo-org.1560.x6.nabble.com/Add-ST-MakeValid-functionality-to-QgsGeometry-td5002449.html
[1] https://github.com/mxcl/homebrew/issues/20373

Regards,

Larry



> All the best.
> - --
> Paolo Cavallini - Faunalia
> www.faunalia.eu
> Full contact details at www.faunalia.eu/pc
> Nuovi corsi QGIS e PostGIS: http://www.faunalia.it/calendario
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