[mapserver-users] Mapfile CLASS hierarchy

[lars.schylberg at blixtmail.se]

This blog entry from Simon Mercier describes how this works.




http://www.mapgears.com/en/blog/archive/2013-03-05-roads_network_mapping




Lars S.



-----Originalmeddelande----- 
> Från: "Stephen Woodbridge" <woodbri at swoodbridge.com> 
> Till: mapserver-users at lists.osgeo.org 
> Datum: 2017-01-22 05:35 
> Ämne: Re: [mapserver-users] Mapfile CLASS hierarchy 
> 
> Oh, and I forgot to mention that if you want objects rendered in a 
> particular order, then your should sort the data in the sources in that 
> order. You can do this with order by clause on SQL based data sources 
> and using shpsort for shapefiles, ogr2ogr and also sort data.
> 
> On 1/21/2017 10:03 PM, Stephen Woodbridge wrote:
> > Within a layer objects are always drawn in the order they are delivered
> > from the datasource. Think of the CLASSes are an IF-ELSEIF-BLOCK, when
> > an object is presented each CLASS is tested and the first one the
> > accepts the object renders it.
> >
> > I often up a default class at then end that has no expression ans render
> > it in red just so I can see if I missed any cases, but remove it when
> > I'm done developing the mapfile.
> >
> > -Steve W
> >
> > On 1/21/2017 8:48 PM, Stefanos Anastasiou wrote:
> >> Hi list,
> >>    according to the documentation, the first layer in the mapfile is
> >> drawn first, and the second is drawn on top of that and so on... I was
> >> wondering if the same principle applies to the CLASS object as well. For
> >> example: I have a "Roads" layer stored in PostGIS with a "Category"
> >> column representing the different types of roads. So a category 3 is
> >> very small roads, category 2 is city roads, 1 is major roads and 0 is
> >> highways and on the same layers I create four CLASS objects with
> >> different styles for each Road category. But regardless the order of the
> >> classes (either I draw the small roads first or the highways) the same
> >> effect insists: the small roads are drawn over the highways.    So what
> >> is the solution here? Create different layers of the same dataset
> >> representing the various values of the "Category" column ??
> >>
> >>
> >> Regards,
> >> -Stefanos
> >>
> >>
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> >>
> >
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