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
>
>
--
Andreas Hocevar
OpenGeo - http://opengeo.org/
Expert service straight from the developers.
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