dynamic symbols, eg bar graphs or pie charts

[thomas bonfort]

am I missing something or can this already be done online with arbitrary
data? without an angleitem and startangleitem and some "not so easy" postgis
processing for the start angles, I don't get it.
The advantage here is using arbitrary data, and in this context can be
easily extended to bar graphs for example.
I couldn't find any reference to the expressions bindings you talk about,
any pointers?

tb

On 6/13/06, Steve Lime <Steve.Lime at dnr.state.mn.us> wrote:
>
> That is very similar to the chart hack I've done precviously. With postgis
> I would imagine computing angles (from percentages) would be easy. I now see
> a use for Steve W. expression bindings...
>
> Please file a bug to track your additions and we can talk about
> integration.
>
> Steve
>
> >>> thomas bonfort <thomas.bonfort at GMAIL.COM> 06/12/06 2:25 PM >>>
> hi there,
> I quickly hacked up something, finally leaving out gdchart mainly because
> I
> was too lazy to modify it so it accepts a gdhandle rather than file
> pointers, but also because the sizes of the output charts were'nt
> consistent
> with one another.
> I've attached a jpeg image of the output.
> basically so as to keep the "class" parts semantically correct, I use a
> new
> layer type "CHART", in which each class corresponds to a slice of the pie
> chart, and the sizeitem to the value. the example shown here is therefore:
>
> LAYER
>     NAME "ages"
>     TYPE CHART
>       CONNECTIONTYPE postgis
>       CONNECTION "blabla"
>       DATA "the_geom from demo"
>       STATUS ON
>       CLASS
>            NAME "population age 0-19"
>           STYLE
>                  SIZEITEM "v1006"
>                  COLOR 255 244 237
>              END
>       END
>       CLASS
>           NAME "population age 20-39"
>           STYLE
>                  SIZEITEM "v1007"
>                 COLOR 255 217 191
>             END
>       END
>       CLASS
>           NAME "population age 40-59"
>           STYLE
>                  SIZEITEM "v1008"
>                 COLOR 255 186 140
>             END
>       END
> END
>
> I'd hope this could be integrated/expanded in a future version, keep in
> touch if you're interested.
> cheers,
> tb
>
>
> On 6/9/06, Daniel Morissette <dmorissette at mapgears.com> wrote:
> >
> > thomas bonfort wrote:
> > >
> > > Steve and Daniel: the url type symbol does seem promising
> feature-wise.
> > > but once again the overhead of network request and probably two
> > > intermediate files (one for owt, one for MS) seems quite important.
> > >
> >
> > True, there can be a performance hit for large numbers of symbols, but
> > using an external service via a URL to produce the chart or dynamic
> > symbol gives maximum flexibility to the users to return whatever they
> > like and not just charts.
> >
> > Anyway, if you insist on direct integration inside MapServer, then I'd
> > recommend that you look at gdchart which is used by OWTChart
> > (http://maptools.org/owtchart/)... the original version of gdchart was
> > messy with a bunch of global variables and static stuff that didn't
> > build well on all platforms, and for owtchart I reworked it to replace
> > the global vars with a struct and make it more multi-platform. You'll
> > find that version in directory "gdchart2" in the owtchart source
> > package. The only other dependency of gdchart is GD (and its own
> > dependencies), that would be fairly easy to integrate.
> >
> > Daniel
> > --
> > Daniel Morissette
> > http://www.mapgears.com/
> >
>
>
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