[mapserver-dev] LAYER EXTENT

[Tamas Szekeres]

Hi Paul,

layer->extent is used to provide data for msLayerGetExtent. If layer->extent
is set then this value is used, otherwise the  driver-specific
implementation is called which may be much slower and some of the drivers
don't implement to retrieve it. I assume layer->extent is defined in the
layer coordinate system.
I think you could easily use this in msLayerIsVisible (assuming it does
nothing if the extent is not set ). I don't see the necessity have an RFC
with this.

Best regards,

Tamas



2009/6/4 Paul Ramsey <pramsey at opengeo.org>

> I see we have an EXTENT keyword under LAYER, but poking around the
> code, layerObj->extent is not used very much.
>
> I have a client request to use LAYER EXTENT as a processing short
> circuit, so that layers whose extent does not intersect the map extent
> can be quickly skipped (probably at the point where msLayerIsVisible()
> is called).
>
> First, does this feel RFC worthy? (My feeling is "no", it's just an
> enhancement of existing behavior)
> Second, what are the expected semantics of the coordinates in LAYER
> EXTENT. Are they in the LAYER projection or the MAP projection? (My
> feeling is, LAYER).
>
> Thanks,
>
> Paul
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