[Community] Symbolizer Usability
kai.hanninen at mbconcert.fi
Fri Jun 16 11:48:26 EEST 2006
Ludwig M Brinckmann wrote:
> Which PCL Version are you using with this?
I'm using the SVN head of both PCL and ZCO.
>> From: Kai Hänninen <kai.hanninen at mbconcert.fi>
>> Reply-To: "gispython.org community projects"
>> <community at lists.gispython.org>
>> To: "gispython.org community projects" <community at lists.gispython.org>
>> Subject: Re: [Community] Symbolizer Usability
>> Date: Thu, 15 Jun 2006 16:40:57 +0300
>> Kai Hänninen wrote:
>>> Hi Ludwig!
>>> Thanks for your feedback.
>>> Ludwig M Brinckmann wrote:
>>>> -- Symbolizers should be reusable across layers (so in that sense
>>>> the old ZCO style was better) This is maybe not so much an issue
>>>> now, but I hope we will one day get layer groups.
>>> Right, PrimaGIS 0.6 will not support this, but later versions based
>>> on the Zope3 Component Architecture will.
>> I attempted to improve the use case for sharing symbolizers and
>> committed a proposal in r714 for PrimaGIS.
>> The old implementation (revisions < 714) used a containment based
>> approach so that the symbolizers used for a given layer needed to be
>> physically located within that layer.
>> I've replaced that with a reference based implementation so that the
>> layer stores only references to symbolizer objects within it and this
>> - Symbolizers to be shared among different layers
>> - Symbolizers to be located freely within the Plone site
>> For a site with a single map this approach will work ok, but for
>> multiple maps per site installations we might wish to constrain the
>> symbolizers used for a given map to be contained within that
>> particular map so avoid polluting the symbolizer selection with lots
>> of unrelated symbolizers.
>> This approach may be a bit slower to render than the one before
>> because we need to do a catalog query to access the symbolizers
>> instead of a direct access. If it does prove to be useful, I'm sure we
>> can optimize it though.
>> This is merely a step in the evolution because in the zope3 based
>> PrimaGIS the symbolizers are defined in ZCML and not persisted in the
>> ZODB (although we can implement TTW created persisted symbolizers if
>> need be).
>> If you try this, I suggest you do it with a fresh installation and use
>> the createPrimaGISDemo script instead of upgrading an existing setup
>> because the migration code is not up-to-speed on this.
>> Looking forward to your feedback!
>> Kai Hänninen +358-50-558-7935
>> Software engineer www.mbconcert.fi
>> MB Concert Ky kai.hanninen at mbconcert.fi
>> Community mailing list
>> Community at lists.gispython.org
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Kai Hänninen +358-50-558-7935
Software engineer www.mbconcert.fi
MB Concert Ky kai.hanninen at mbconcert.fi
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