Jody Garnett ha scritto: > On Sat, Apr 25, 2009 at 3:29 AM, Andrea Aime <[email protected]> wrote: >> Hi, >> I would like to create a new community module that is going >> to provide chart rendering for ExternalGraphic leveraging >> ExternalGraphic, the dynamic symbolizers feature, and the >> JFreeChart library by means of the Eastwood charts project: >> http://www.jfree.org/eastwood/ > > Fun stuff. Is eastwood that much better of an api for JFreeChart? > >> The dynamic symbolizer abilities to pass over feature attributes >> in ExternalGraphics url has already been leveraged in GeoServer >> land to use Google Charts API directly, but that is subject >> to some limitations: >> - performance is poor due to the remote requests to compute charts >> - dependency on a free service that has no guarantees to be there or be >> performant enough >> - issues with Google deciding, one day, to change the term of service. > > Okay that answers my question; you are probably looking to reuse some > existing chart making code.
Last Sunday I started the day looking around for options for chart making. I started writing this page: http://docs.codehaus.org/display/geotools/Charting+with+dynamic+symbolizers At the beginning of the afternoon I stumbled into Eastwood charts. I asked myself... could it be this easy to implement? By dinner I had pie charts popping up on my maps. >> PS: hmmm, I already hear someone saying that having >> a full blown ChartSymbolizer would have been nicer. >> And well, it would have been, no doubt about it. >> Yet, going down that route would have taken much more >> time I have available, whilst I managed to do this in >> a bit more than one day. > > Actually this would be a nice way to test out the ExtensionSymbolizer > thing (using the name "chart"). So far it has been (and will remain) a weekend toy. With proper funding I can tackle the approach of making a full blown symbolizer instead. However, if you look at the functionality already provided by Eastwood "for free" you'll realize that only duplicating what's already there will take significant time. We tried to make this a summer of code project this year, yet, even a skilled student working on a full blown symbolizer would have been able to just make a fraction of what Eastwood does already. If I were to redo this myself, I would estimate no less than two weeks or work, coding in anger, with no distractions whatsoever. Actually my first idea was to try and make an external template, a chart description file, that the dynamic symbolizer approach could refer to, and fill in with data and eventually titles and the like. I was looking for a ready made JFreeChart description format when I stumbled into Eastwood and decided that it was good enough given the context in which I was playing (weekend project). Trying to stick all of the options JFreeChart provides into a ChartSymbolizer would result in a massive xml element with lots of sub-options (which would also be hard to write out for a user). One of the other advantages of using the Google Chart API though Eastwood is that Google already did the work of figuring out the common set of options that most people are interested into (not an easy task imho). Cheers Andrea -- Andrea Aime OpenGeo - http://opengeo.org Expert service straight from the developers. ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensign option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Geotools-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-devel
