[OpenLayers-Dev] vector layer with highest zIndex not overlaying other vector layers

[Andreas Hocevar]

Hi,

not sure if it applies in your case, but usually you don't need an extra layer for your selected features. If you have a SelectFeature control, all the layers that you have configured it with move to the top automatically. And you can use the "select" renderIntent of your layer's stylemap to make the seleted features look the way you want to.

Regards,
Andreas.

On Oct 1, 2010, at 21:02 , crb wrote:

> 
> Apologies for the duplicate posting, but it morphed from the original posting
> that had a subject with a (probably well-known) unsupported feature.  
> 
> I'm having trouble w/ an aspect of a solution I'm trying to implement, and
> that is having one vector layer (a "selected features" layer) display over
> the top of another "location features" layer. Even though the zIndex of the
> "selected features" layer is higher (as I can see when stepping through
> Map.js.setLayerZIndex()) it's still not displaying over the "location
> features" layer, even after a map.resetLayersZIndex(). 
> 
> Maybe there's another way around what I'm trying to do, but I think getting
> the one vector feature to display over the top of the other will work. 
> 
> Ultimately the issue I'm trying to resolve is that having too many vector
> features in the map (hundreds at a time) slows the browser performance down
> too much (esp. IE, which is unusable).  We were originally loading all
> vector features on map init. We changed it so that: 
>   - vector features only display at a specific, zoomed-in scale 
>   - only the features in the current map extent are displayed (i.e. the
> callback to get the features is run on each map moveend event) 
>   - features use a cluster strategy 
> 
> This all works fine.  Now the problem comes with selected features, which
> we'd like to show at *all* scales, since they should only ever be a small
> enough subset of all features that they don't affect browser performance,
> and they are visible to the user regardless of the scale that they switch
> to.  Originally we thought we would solve this by doing the following when a
> feature in the "location features" layer is selected: 
> 1. clone the feature in the "location features" layer and add it to the
> "selected features" layer (which has a higher zIndex), hoping that the
> feature in the "selected features" layer would display over the top of the
> locations layer 
> 2. show a popup on the feature (has to be the "location features" layer
> since only it can have an associated SelectFeatures control) 
> 
> When unselecting the feature: 
> 1. delete the cloned feature from the "selected features" layer 
> 2. close the popup 
> 
> As you can see, this only works if the "selected features" layer actually
> displays over the top of the "location features" layer.  Not sure yet if the
> 'selected' event will fire on the "location features" layer if the "selected
> features" layer (eventually) overlays it. 
> 
> What's not working: 
> - when selecting a single (non-clustered) feature in the "location features"
> layer: 
>     * all features in that layer briefly disappear 
>     * the newly-added feature in the "selected features" layer briefly
> appears 
>     * the popup appears 
>     * the "location features" layer overlays the "selected features" layer 
> If I turn off the "location features" layer, I see this first feature (only)
> in the "selected features" layer 
> - only the first single selected feature is added to the "selected featues"
> layer: subsequently-selected single features are not (even though when
> debugging I can clearly see the call to
> 'selsLayerDef.addFeatures([feature])' executed) 
> - when clustered features in the "location features" layer are selected,
> they are not added to the "selected features" layer, even though when
> selecting them I can see the array getting added: 
> 
> for (var i = 0; i < feature.cluster.length; i++) {
>   hFeatures.push(feature.cluster[i].clone());
> }
> selsLayerDef.addFeatures(hFeatures); 
> 
> - on the SelectFeature control, both 'clickout' and 'toggle' are set to
> 'true', but when I do either in the map then the function associated with
> onUnselect does not fire 
> 
> Note that 'displayInLayerSwitcher' is set to 'false' on my "selected
> features" layer.  It correctly doesn't show up in the layer switcher, but
> given its higher zIndex I would still expect it to render over the top of
> the "location features" layer.
> 
> Should I be going about this a different way? 
> -- 
> View this message in context: http://osgeo-org.1803224.n2.nabble.com/vector-layer-with-highest-zIndex-not-overlaying-other-vector-layers-tp5592538p5592538.html
> Sent from the OpenLayers Dev mailing list archive at Nabble.com.
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-- 
Andreas Hocevar
OpenGeo - http://opengeo.org/
Expert service straight from the developers.