[Qgis-user] Understanding the rule-based renderer

[Andreas Neumann]

 Hi Martin,

 Thank you for the explanation. I believe that a) option is more natural 
 to users. But of course we would also need a way to later change the 
 order of the rules - once they are created.

 For now I am just using additional layers until the rule-based renderer 
 behaves like a) or SLD.

 Thanks,
 Andreas

 On Fri, 8 Apr 2011 12:25:03 +0200, Martin Dobias wrote:
> On Fri, Apr 8, 2011 at 11:36 AM, Andreas Neumann 
> <a.neumann at carto.net> wrote:
>> Hi,
>>
>> I am trying to better understand the rule based renderer.
>>
>> Which version is correct?
>>
>> a) QGIS is rendering all features of the first rule, then the second 
>> rule,
>> etc, Features of the first rule are rendered first, features of the 
>> second
>> rule on top of features from the first rule
>> b) QGIS is rendering each feature on by one and decides which rule 
>> applies.
>>
>> I hope it is not version b), I hoped it behaves like version a) but 
>> it
>> behaves a bit odd with my data. For my data it seems like the order 
>> of the
>> rule has no influence on the rendering order ;-(
>
> Hi Andreas
>
> the rule based renderer uses the b) option: it goes through the
> features one by one and applies all matching rules (in the order in
> which they appear). Mayeul Kaufmann has done some work in order to
> support option a) by implementing support for symbol levels so that
> the rendering order can be overridden.
>
> My ultimate goal is to only support the option a) in a way how SLD
> specifies it: rules are grouped and these groups are rendered one
> after each other.
>
> Regards
> Martin

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 Andreas Neumann
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 8624 Grüt (Gossau ZH)
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