[Qgis-user] data defined style with $scale

[Ziegler Stefan]

Hi Andreas

for me it seems unlogical. The CASE-WHEN-ELSE statement is returning zero for scales larger than 1000. So I don't see any reason why QGIS draws a line with an unpredictable line-width. 

I do not have access at the very moment to QGIS. But what happens when you just enter 0.0 as data defined line-width?

regards
Stefan

Von meinem iPad gesendet

> Am 19.11.2013 um 11:59 schrieb "Andreas Neumann" <a.neumann at carto.net>:
> 
> Hi Stefan,
> 
> This seems logical to me. The data-defined styling only changes a graphical property. It does not control whether a feature is drawn or not. You could set it to fully transparent, but this would still fetch features and draw them (though invisible).
> 
> If you want to suprress features above a certain level you may do that on the layer level in the "General settings" (or something similar).
> 
> The labels individually allow to suppress labels based on a column or expression, but the data-defined symbology does not allow that so far. It would be a new feature to ask for.
> 
> Andreas
> 
> Am 2013-11-19 07:50, schrieb Ziegler Stefan:
>> Hi
>> I have a question regarding data defined styling. I'm using the $scale
>> parameter to define the line width:
>> CASE
>> WHEN $scale <= 500.0 THEN 1
>> WHEN ($scale > 500 AND $scale <= 1000) THEN 0.5
>> END
>> I would expect that the line is not drawn with a scale larger than
>> 1000. But it seems the line is still drawn. It even draws the line
>> with an ELSE-statement:
>> CASE
>> WHEN $scale <= 500.0 THEN 1
>> WHEN ($scale > 500 AND $scale <= 1000) THEN 0.5
>> ELSE 0.0
>> END
>> It seems that I get my expected result when I use an ELSE value near
>> zero (e.g. 0.0000001).
>> Is this on purpose? Or is there an error in my statement?
>> regards
>> Stefan
>> Freundliche Grüsse
>> Stefan Ziegler
>> Kantonsgeometer
>> Amt für Geoinformation
>> Amtliche Vermessung
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>> 4500 Solothurn
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