[OpenLayers-Users] Layer.Vector with multiple data sources

[Arnd Wippermann]

Hi Alexandre,

If you have found a solution, I would be interested. I have thought about a
solution with all features on one vectorlayer and an attribute "group". I'm
able to set the style of the features due to the zoomlevel, but I have no
clue to hide features.

// create the layer styleMap by giving the default style a context
var colors = ["#FF0000", "#FF8000", "#FFFF00", "#80FF00", "#00FF00"];
var context = {
    getColor: function(feature) {
        var region = parseInt(feature.attributes['group']);
        if(map.getZoom()>5)
            return colors[region];
        return colors[map.getZoom()];
    }
};
var template = {
    fillColor: "${getColor}", // using context.getColor(feature)
    strokeColor: "#FF0000",
    strokeWidth:3
};
map.layers[map.aktLayer].styleMap = new OpenLayers.Style(template, {context:
context});
map.layers[map.aktLayer].redraw();

Perhaps Andreas you could gave a hint. In a previous post you have mentioned
display:"none" to hide features, but i don't know where to use it.

Especially can I use display:"none" with context and template?

Arnd Wippermann






 

-----Ursprüngliche Nachricht-----
Von: users-bounces at openlayers.org [mailto:users-bounces at openlayers.org] Im
Auftrag von Andreas Hocevar
Gesendet: Samstag, 3. Januar 2009 17:30
An: Heidt, Christopher M.
Cc: users at openlayers.org
Betreff: Re: [OpenLayers-Users] Hide features

Hi,

On Wed, Dec 3, 2008 at 10:05 PM, Heidt, Christopher M.
<CHRISTOPHER.M.HEIDT at saic.com> wrote:
> How do I hide features?
> I did it by changing my opacity to 0,
> but I need to find another way because my features can have multiple 
> styles, and I need the feature to retain whatever style it has when 
> hidden and reshown.

You just need to set the symbolizer (style) property "display" to "none"
(like in CSS).

So instead of
var symbolizer = {
    opacity: 0
}

you set

var symbolizer = {
    ...
    display: "none",
    ...
}

No other symbolizer properties will be lost (but the same is true for your
opacity hack), and the feature will not be rendered until you delete the
display property (or set it to a value other than "none").

Regards,
Andreas.


--
Andreas Hocevar
OpenGeo - http://opengeo.org/
Expert service straight from the developers.
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-----Ursprüngliche Nachricht-----
Von: users-bounces at openlayers.org [mailto:users-bounces at openlayers.org] Im
Auftrag von Alexandre Dube
Gesendet: Donnerstag, 8. Januar 2009 19:38
An: Andreas Hocevar
Cc: OpenLayers users mailing list
Betreff: Re: [OpenLayers-Users] Layer.Vector with multiple data sources

Andreas Hocevar wrote:
> On Thu, Jan 8, 2009 at 6:42 PM, Alexandre Dube <adube at mapgears.com> wrote:
>   
>> Andreas Hocevar wrote:
>>     
>>> Alexandre Dube wrote:
>>> It should be easy to customize the strategy you are using (I assume 
>>> Fixed or BBOX) to change the url and/or params of the protocol on 
>>> the zoomend event (similar to the moveend event handler in the BBOX 
>>> strategy). This strategy would then have to know the urls/params for 
>>> each zoom level, and you would just interact with one vector layer.
>>>
>>>       
>> Exactly.  It's a common practice on the web to have data normalized 
>> by scales, so it would be quite useful to have such an upgrade.
>>
>> So, you would modify both BBOX and Fixed ?  Do others have opinions 
>> about it ?
>>     
>
> No, I'd encourage you to do this on the application level because it 
> is less than 10 lines of code. If this is to become part of 
> OpenLayers, it should be a separate strategy (a layer can have 
> multiple strategies).
>
> Regards,
> Andreas.
>
>   

Understood.  I'll try to write a new strategy then.  Thanks a lot for the
tips.

--
Alexandre Dubé
Mapgears
www.mapgears.com

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