[postgis-devel] Re: [postgis-users] postgis.jar file does not contain latest geometry types
schabi at logix-tt.com
Thu Dec 14 02:12:47 PST 2006
Ken Southerland <southerland at samsix.com> wrote:
> > The problem I see right off the bat here is that GeneralPath does not have
> > an arcTo() method and the only curve that is implemented currently in the
> > new postgis is an arc.
The reason for the latter is that the ISO MM spec only contains arcs.
> > Sheesh. I'm almost thinking about cheating (not
> > with the official java2d mapping but with my own mapping) and just
> > pretending like the arc stored is really a Quadratic Curve.
You can also investigate and mimic how java.awt.geom.Arc2D and
java.awt.geom.Ellipse2D map their geometries into PathIterator
primitives. Maybe you need several java2d Path segments for a ISO MM
segment that contains a full circle, but at least a lossless geometric
mapping should be possible.
> Let me know if this discussion is best for the devel list in general. Having
> just joined I don't know the protocol just yet. And let me know if I'm being
> too pesky. :)
Yes, it's best do discuss this on the devel list, so I Cc'ed it.
> So, I have an answer for my own issue. The batik project
> (http://xmlgraphics.apache.org/batik/) has
> org.apache.batik.ext.awt.geom.ExtendedGeneralPath class which extends
> GeneralPath by simply adding an arcTo() method to it! Not surprisingly
> someone has already run into this problem.
But the main reason why they extended the GeneralPath model is that
> What is your feeling about requiring the java2d mapping to depend on the batik
> project in order to make use of this feature. They nicely have their jar
> files all broken up into small chunks and the one needed here
> (batik-awt-util.jar) is only 361K.
I would prefer to stay without batik if possible, because I don't want
to pull in other build dependencies.
 SUN's jdk source is available for "educational purposes", and you
can see how the ClassPath people did it.
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf. | Software Development GIS
Fight against software patents in Europe! www.ffii.org
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