Thanks for checking - so it is a QGIS rendering issue and has nothing to
do with data-defined styling.
A new feature would still be the ability to draw or not draw a feature
(boolean) based on an expression. Would be interesting to have in some
cases.
Andreas
Am 2013-11-19 16:15, schrieb Ziegler Stefan:
Hi
I just tried a line-width "0" and it is rendered (no data defined
stuff, only simple styling).
Regards
Stefan
-----Ursprüngliche Nachricht-----
Von: Andreas Neumann [mailto:[email protected]]
Gesendet: Dienstag, 19. November 2013 14:15
An: Ziegler Stefan
Cc: [email protected]
Betreff: Re: [Qgis-user] data defined style with $scale
Hi,
If a line-width with "0" is rendered than it is a rendering issue and
not a logical issue.
The CASE WHEN ELSE END statement always returns a value. That's what I
meant that
it seems logical to me.
I don't think that QGIS does suppress the rendering of lines with zero
width. It just
passes it on to the render with a line-width value of zero. If the
renderer still draws
the line it is a bug in the renderer.
Of course could check if the line-width is zero and suppress the line.
But I don't know much about the renderer internals to know how QGIS is
handling it.
Andreas
Am 2013-11-19 13:16, schrieb 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"
>> <[email protected]>:
>>
>> 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
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