[mapserver-dev] Using area expression in label text

Steve Lime sdlime at gmail.com
Wed Jul 15 13:13:43 PDT 2020

Sorry, been on vacation... Anyway, presumably you're not using a database
backend? If that's the case then I don't know that what you're trying to do
is possible. The shape, when made available to the labeling code, has
already been transformed (and I think clipped). I'm not sure why
[map_cellsize] resolves to 0 though since the value is well known at that
point in the processing. I don't recall who/when that support was added.

On Thu, Jul 9, 2020 at 3:21 PM Tamas Szekeres <szekerest at gmail.com> wrote:

> Hi Devs,
> I wanted to add label text to a layer to display the computed area value
> in the label. Tried using this expression:
> TEXT (area([shape]))
> but that calculates the area in pixel space which is useless for the
> purpose. I've also tried to utilize [map_cellsize] in the expression to
> convert the area to map units, but [map_cellsize] always returns 0 in this
> use case.
> Can anyone explain how to use area in the text expression to get correct
> result?
> Thanks,
> Tamas
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> mapserver-dev at lists.osgeo.org
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