An alternative to changing the layer group info is to change the layer to
include min/max scale information. Ideally do to DRY (do not repeat
yourself) I would like to see the min/max scale calculated from the style
... and refreshed each time the style is changed.

I guess it is tricky as the scale based on which style the user has
requested; or in this case the layer group has been configured with.

In the WMS module during a GetMap request (rather than adjust the styles
using a style visitor) you could discard layers that do not match the
current scale from further processing


--
Jody Garnett

On 12 June 2015 at 11:43, Kevin Smith <[email protected]> wrote:

> I'm looking at ways we could make it easier to manage scale based
> visibility of layers in a layer group.
>
> At the moment I'm thinking the best way to do it would be to add a list of
> scale ranges to layer groups in parallel to the existing lists of
> publishables and styles with the same pair of accessors (one for children,
> one for a flattened list of descendants)
>
> Then in the WMS module when the StyleInfo objects are retrieved and used
> to get the Style objects (Happens in two places, one for GetMap, one for
> GetLegend), a StyleVisitor could be sent over the styles to adjust the
> scale rules so they are suitably restricted.
>
> This would simplify the process of building complex layer groups as it
> would place all the scale dependant visibility information in one place
> instead of having to coordinate it across multiple styles.
>
> This would either require a new kind of layer group that the WMS module
> would have to detect, or a change to the LayerGroupInfo interface to add
> new methods.  I expect the latter would call for a GSIP.
>
> Does anyone have any thoughts?
>
> --
>
> Kevin Smith
>
> Software Engineer | Boundless <http://boundlessgeo.com/>
>
> [email protected]
>
> +1-778-785-7459
>
> @boundlessgeo <http://twitter.com/boundlessgeo/>
>
>
> <http://twitter.com/boundlessgeo/>
>
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>
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