[Users] Displaying customs icons in one layer

[Tim Schaub]

Pol wrote:
> Yes ! It's working :)
> 
> Thanks for your reply !!!
> 
> Can you explain or show me some example with 'rules' ?
> 

http://openlayers.org/dev/examples/style-rules.html

> That will probably reduce the size of my json and I'll learn something new
> too ;)
> 
> Thanks! :)
> 
> -Pol D.-
> http://www.google.com/profiles/110003197662276240659
> 
> 
> On Tue, Mar 23, 2010 at 23:24, Tim Schaub <tschaub at opengeo.org> wrote:
> 
>> Pol wrote:
>>> Hello,
>>>
>>> I just discovered GeoExt and OpenLayers 2 days ago and I'm rebuilding my
>>> project using GeoExt (it was using the very good GmapPanel before).
>>> First of all, thanks for it, it's a very good job !
>>>
>> Thanks.  Welcome.
>>
>>> I subscribe to this list because I have a small problem.
>>>
>>> I have a single URL who return me all the markers to display on the map.
>>> Those markers must have different icons.
>>>
>>> I don't want to create multiple layers for each kind of markers, that
>> would
>>> make too much external calls and slow down the whole stuff.
>>>
>>> I have pasted some bits of code here: http://pastebin.com/Uee7xdzJ
>>>
>>> I suppose that I have to add a property like:
>>>
>>> imgRef: 1
>>>
>>> in my json response to identify the picture to display in javascript
>> later,
>>> but I don't know where to put it and how to retrieve it.
>>>
>>> Can you help me ?
>> Your vector layer will contain a collection of vector features.
>> OpenLayers.Feature.Vector objects have an "attributes" property.  You'll
>> need to have a feature attribute that can be used to derive the path to
>> the image you'd like to use for rendering those features.
>>
>> In the simplest case, your features have an attribute whose value is the
>> path to an external graphic.  In this case, you will be using a
>> symbolizer that refers to the appropriate feature attribute.
>>
>> e.g.
>>
>>     // assuming feature.attributes.icon = "path/to/marker.png"
>>     var symbolizer = {
>>         graphicHeight: 10,
>>         graphicWidth: 5,
>>         externalGraphic: "${icon}"
>>     };
>>
>> This symbolizer is used to create an OpenLayers.Style object that is
>> referenced in an OpenLayers.StyleMap (yes, complicated).
>>
>> See http://openlayers.org/dev/examples/styles-rotation.html for a
>> similar example using feature attribute values for rotation and fill
>> opacity.
>>
>> It looks like you are using GeoJSON as your transport format.  Your
>> OpenLayers feature object would look something like the following when
>> serialized:
>>
>>     {
>>         "type": "Feature",
>>         "geometry": {
>>             "type": "Point",
>>             "coordinates": [4.22, 50.72]
>>         },
>>         "properties": {
>>             "icon": "path/to/marker.png"
>>         }
>>     }
>>
>> The "properties" member of a GeoJSON feature object maps to the
>> attributes object of an OpenLayers vector feature.
>>
>> If you don't want to include the path to your external graphic in your
>> data, but instead you want to render your features based on some other
>> combination of attributes, you can use rule based styling.  Write back
>> if that's what you're after.
>>
>> And, you might find the OpenLayers lists a more appropriate place for
>> pure OpenLayers questions.
>>
>> Good luck,
>> Tim
>>
>>
>>> Thanks.
>>>
>>> -Pol D.-
>>>
>>>
>>>
>>> ------------------------------------------------------------------------
>>>
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>>> http://www.geoext.org/cgi-bin/mailman/listinfo/users
>>
>> --
>> Tim Schaub
>> OpenGeo - http://opengeo.org
>> Expert service straight from the developers.
>> _______________________________________________
>> Users mailing list
>> Users at geoext.org
>> http://www.geoext.org/cgi-bin/mailman/listinfo/users
>>
> 
> 
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> 
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-- 
Tim Schaub
OpenGeo - http://opengeo.org
Expert service straight from the developers.