Andreas, Eric, Cédric,
Thanks to all of you for your support. Your answers are very clear
and well detailed. I'll make the changes according to what you proposed
and come back if I have any more questions.
Thanks again,
Alexandre
Andreas Hocevar wrote:
> Hi,
>
> Alexandre Dube wrote:
>> I want to be able to save a OpenLayers.Style object or hash to a
>> vector feature. Currently, in code, feature.style exists but you
>> must define a hash or else it doesn't work.
>>
>
> That's correct and expected. Let's call your hash "symbolizer".
>
>> My problem is that I want to be able to draw features to be used as
>> labels (floating text on the map). To be able to do so, I need to
>> define a StyleMap with a context to display the label (I manually set
>> feature.isLabel on "featureadded") [1]
>>
>
> You can evaluate the symbolizer from the context before setting
> feature.style:
>
> feature.style = myStyleMap.styles["default"].createSymbolizer(feature);
>
>> That works well, but as soon as I want to "bind / save" the style
>> to the feature, I mean set feature.style, I need to set a hash and
>> the feature will be rendered without the contexts.
>>
>
> The above snippet creates a symbolizer from the default style of the
> style map, and evaluates everything from the context.
>
>> I don't fully understand how the contexts, symbolizers, etc. work,
>> but my first guess would be to support OpenLayers.Style object
>> directly in the feature object. Does that make sense ?
>>
>
> No. Context-based styling and symbolizers-per-feature are two
> different things.
>
>> Or maybe I'm doing it wrong and their's an other way of "labeling"
>> features. My goal is to create features on a "cosmetic" layer with a
>> default style, then to be able to change the style of the features
>> and bind it to them (I mean without using rules on the layer level,
>> but by defining directly the feature style)
>>
>
> That makes sense, and the snippet above is the solution. You start
> with a layer with a StyleMap, and to override the evaluated style for
> a specific feature, you set feature.style with the symbolizer you get
> from Style::createSymbolizer.
>
> Note that if you want to change the label for such a feature later,
> you need to set symbolizer.label, not feature.attributes.name.
>
> Also note that if you want a point feature with just a label and
> without the geometry rendered, it is better to set the graphic: false
> symbolizer property instead of pointRadius: 0.
>
> Regards,
> Andreas.
>
>> Many many thanks,
>>
>> Alexandre
>>
>>
>> // [1] START
>> var labelStyle = {
>> label: "${name}",
>> labelSelect: true,
>> pointRadius: "${radius}"
>> };
>> var styleOptions = {
>> context: {
>> 'name': function(feature) {
>> var szValue;
>> if (feature.attributes['name'] &&
>> feature.isLabel === true) {
>> szValue = feature.attributes['name'];
>> } else {
>> szValue = "";
>> }
>> return szValue;
>> },
>> 'radius': function(feature) {
>> return (feature.isLabel === true) ? 0 : 6;
>> }
>> }
>> };
>>
>> var style = new OpenLayers.Style(
>> OpenLayers.Util.applyDefaults(
>>
>> labelStyle,OpenLayers.Feature.Vector.style["default"]),
>> styleOptions
>> );
>>
>> var styleMap = new OpenLayers.StyleMap({
>> "default": style
>> });
>> layer = new OpenLayers.Layer.Vector(
>> "Cosmetic", {'styleMap': styleMap});
>>
>> // [1] END
>>
>>
>
>
--
Alexandre Dubé
Mapgears
www.mapgears.com
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