[mapserver-users] Need help with shpxy centriod in template file

[Lime, Steve D (MNIT)]

The centroid in the shpxy code is very basic and not a true centroid, it's just the mid-point of the bounding box of shape in question. It really wouldn't need to be this simple I think. The computation of that value is done on the raw shape and converted to image coordinates. I'm guessing it's the way the "centroid" is computed that is causing the problem?

Steve

-----Original Message-----
From: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Kent Richards
Sent: Sunday, March 31, 2013 1:13 AM
To: mapserver-users at lists.osgeo.org
Subject: [mapserver-users] Need help with shpxy centriod in template file

When using the imagemap output in mapscript, I'm trying to get the center of the shapes using [shpxy precision=0 proj=image centroid=true].

Perhaps the first most obvious question is: am I misunderstanding what "centroid" means in this case?  I thought it meant the geometric center of the shape (of each shape, in this case).

I have an imagemap TEMPLATE file with this declaration:

> <!-- MapServer Template -->
> <area class="[shpxy precision=0 proj=image centroid=true xh="x" xf="-" yh="y" sh="center-"]" shape="poly" coords="[shpxy precision=0 proj=image]" href="http://my.url/mypage.cfm?ID=[state]" title="[state]" alt="[state]">


The [shpxy centroid-true...] part returns "center-x367-y128" *for each shape* (the raw coords are 367, 128).

367, 128 is not in the center of the image, nor in the center of most of the shapes.

The other shpxy declaration in the template -- for the coords attribute -- seems to behave as expected.

Any ideas what I'm doing wrong, or is this a bug?

I know I can rig a convoluted means to return just the polygon points and calculate a center of sorts myself, but I'd like to just use the mapserver feature if it works.

Thanks,

Kent
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