[Qgis-user] data defined style with $scale

[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:a.neumann at carto.net]
> Gesendet: Dienstag, 19. November 2013 14:15
> An: Ziegler Stefan
> Cc: qgis-user at lists.osgeo.org
> 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"
> >> <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
> >>> Rötistrasse 4
> >>> 4500 Solothurn
> >>> Telefon +41 32 627 75 96
> >>> Telefax +41 32 627 75 98
> >>> stefan.ziegler at bd.so.ch
> >>> http://www.so.ch
> >>> _______________________________________________
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