[OpenLayers-Users] LayerSwitcher Event

[Eric Lemoine]

On Thu, Jun 10, 2010 at 11:59 AM, Rahn Hanno (rahn) <rahn at zhaw.ch> wrote:
>
> Hello,
>
> Today I try to realise a "trigger" for my LayerSwitcher. Something like
> "onLayerClick" or so.
>
> I want to start a function if I select/unselect a layer in the
> Layerswitcher. In my Layerswitcher I have a Layer. If I select this Layer,
> then I want to set the opacity from all other layers to 50%. If I unselect
> the Layer the opacity should change again to not transparent.
>
> I think I need a trigger function for that layer. If I select some Layer I
> would fire a function. I think it would be possible, but I don't know how to
> realise.
>
> Perhaps somebody can help me. Or is there something like this already in
> OpenLayers what I have not found?

Two options:

- register a "changelayer" listener on the map

map.on({
    "changelayer": function(e) {
        if(e.property === "visibility") {
            alert("visibility changed (" + e.layer.name + ")");
        }
    }
});

- register a "visibilitychanged" listener on a specific layer

layer.on({
    "visibilitychanged": function() {
        alert"visibility changed (" + layer.name + ")");
    }
});

Hope it helps,

-- 
Eric Lemoine

Camptocamp France SAS
Savoie Technolac, BP 352
73377 Le Bourget du Lac, Cedex

Tel : 00 33 4 79 44 44 96
Mail : eric.lemoine at camptocamp.com
http://www.camptocamp.com