dynamic symbols, eg bar graphs or pie charts

[Steve Lime]

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/
>