[maplab-users] Re: [mapserver-users] scale dependent layers

[woodbri@swoodbridge.com]

This is very similar to what I was trying to do in maplab recently 
using the html_legend stuff. The problem I ran into was that I could 
hide the controls of layers that were not being displayed, but as I 
zoomed in, maplab (PHP/mapscript) could not differentiate the 
difference between the fact that the control was hidden or that the 
user had turned it off.

I thing if we/you are planning a change in this area, it would be 
nice to coordinate it with the maplab team, because we need to be 
able to track the following:

1) user layer status (on/off)   -- tracked in mapscript application
2) mapfile layer status (on/off)  -- status as coded in mapfile
3) layer is viewable status if it was on (on/off)  -- status relative 
to zoom state

Steve does this make sense?
maplab team does this make sense?

-Steve W.

On 11 Sep 2002 at 11:04, Steve Lime wrote:

> If I read you right your interested in the layer controls as opposed
> to the legend (which already respects scale). Well, there's no super
> easy way to do that. You could use javscript to check the map scale
> (using [scale]) against the layer scale and based on that write the
> control. That would work but would require you to have the layer scale
> information in 2 places (in the template and in the mapfile). You
> could of course store the layer scales only in the HTML file and pass
> them to the mapserver (i.e. map_layername_maxscale,
> map_layername_minscale). I think ideally you'd rather gain access to
> the values as stored in the mapfile. There's some real value in that
> so I would propose adding substitutions like
> [layername_maxscale/minscale] and then you could use those in
> combination with [scale] and javascript. Thoughts folks?
> 
> Steve
> 
> Stephen Lime
> Data & Applications Manager
> 
> Minnesota DNR
> 500 Lafayette Road
> St. Paul, MN 55155
> 651-297-2937
> 
> >>> Rob Holloway <rholloway_1999@yahoo.com> 09/11/02 10:34AM >>>
> Hi
> 
> Does anyone know how to keep scale dependent layers
> (i.e layers with a maxscale set) from displaying on
> the template/html form until the specified scale has
> been reached?  For example, in my application a
> buildings layer has a maxscale factor of 100 000 but
> it still shows up in the list of layers that can be
> displayed at full extent.  This would probably be
> confusing to users trying to select that layer at
> large scale.  Any suggestions?
> 
> Cheers
> 
> Rob
> 
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