[ka-Map-users] External link to control Map scroll & Polygon
daniel at ceregatti.org
Thu Aug 3 13:05:12 EDT 2006
I implement a "radius" in one of my ka-map projects
(http://www.lapdonline.org/crimemap search for something like "150 n.
Los Angeles St." in the address form, leaving the rest as default to see
an example). I had originally tried wz_jsgrpahics, but found it to be a
performance hog. I ended up pre-rendering transparent anti-aliased
circle images in png format from 30 to 1500 pixels in radius and simply
placed these in their own canvas with addObjectGeo. I also
pre-calculated a rough "milesPerPixel" for every scale in my map then
used these figures to overlay the appropriate image file.
If you choose to implement this solution, I'll gladly show my code.
> 2006/8/3, Alvin Clay <orionkamap at yahoo.com>:
>> 2) I'd like to draw a semi-transparent circle on the map overlay that
>> has a
>> certain radius and center point. Is there a way in the xmlOverlay to
>> a polygon that is a circle and has a certain radius in miles?
> There isn't a pre-cooked function.
> A possible solution is to write a script that calculates the circle
> (approximated with an n-edge polygon) and produces a polygon or
> linestring directive usable by kaXmlOverlay.
> Another solution is to reuse part of the code on kaXmlOverlay
> (particularly the methods kaXmlSymbol.prototype.draw_*) to draw the
> circle with the calculated radius: in this case you have to provide
> the handling for scale changes.
> ka-Map-users mailing list
> ka-Map-users at lists.maptools.org
More information about the ka-Map-users