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

[woodbri at swoodbridge.com]

On 13 Sep 2002 at 11:44, Paul Spencer wrote:

> Steven, we are going to fix up the legend handling stuff in maplab,
> probably as follows:
> 
> 1. gmapfactory - add capability to track the status of all layers
> regardless of whether they are in the legend or not.  The legend will
> only be used to make layers visible/not visible.  If a layer that was
> previously not visible due to scale becomes visible after a zoom, the
> layer will appear in the legend with its current status
> (on|default/off).  If the layer goes out of scale, any user changes to
> status will be remembered.

This makes sense to me.

> 2. mapbrowser and mapedit preview - all layers are in the legend at
> all times.  The current mechanism is not intelligent enough to
> determine that a user turned a layer of or it went out of scale.  This
> will be updated to include logic for determining if a layer went out
> of scale and will preserve the layer status but dim the layer name in
> the legend. 
>   (I hope that makes sense)

This sounds great. In fact I do not think you want the layers here to 
be hidden. It is important to be able to see what is happening when. 
So graying the layer when it is out of scale it good.

> There is currently no time frame for this.

No problem. Sounds like a good plan for when you get to it.

-Steve W.

> Cheers,
> 
> Paul
> 
> woodbri at swoodbridge.com wrote:
> > 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 at 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
> >>
> >>__________________________________________________
> >>Yahoo! - We Remember
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> >>
> > 
> > 
> > 
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> > 
> 
> 
> -- 
> Paul Spencer
> Applications and Software Development
> DM Solutions Group
> 
>