add support for a context in StyleMap.addUniqueValueRules

Actually, this is not a problem of the StyleMap.addUniqueValueRules method, but of the Rule class in general, because it's context property is static.

An efficient solution would be a modified getContext method in Rule.js:

    getContext: function(feature) {
        var context = this.context;
        if (!context) {
            context = feature.attributes || feature.data;
        }
        if (typeof this.context == "function") {
            context = this.context(feature);
        }
        return context;
    },

With that, the use case could be fulfilled with a slightly modified addUniqueValueRules method in StyleMap.js:

    addUniqueValueRules: function(renderIntent, property, symbolizers,
            context) {
        var rules = [];
        for (var value in symbolizers) {
            rules.push(new OpenLayers.Rule({
                symbolizer: symbolizers[value],
                context: context,
                filter: new OpenLayers.Filter.Comparison({
                    type: OpenLayers.Filter.Comparison.EQUAL_TO,
                    property: property,
                    value: value
                })
            }));
        }
        this.styles[renderIntent].addRules(rules);
    },

To achieve what Pierre wants, his application code would just have to look like the following:

var context = function(feature) {
    return feature;
}

var lookup = {
    "Insert": {fillColor: "green"},
    "Delete": {fillColor: "red"}
}

styleMap.addUniqueValueRules("default", "state", lookup, context);

Although the usage of this Rule context is different than the one of the Style context, this way of doing it feels more intuitive to me.

Andreas, you rock. It also feels more intuitive to me.

Here's a patch including a new test for rule.getContext().

Please review.

Tests pass on FF2. Couldn't really test on IE as tests/Layer/Text.html currently fail.

I can confirm that

• the tests check for the correct things and are valid
• the example is easy to understand and shows the developer how to work with the new feature

Thanks for putting this together in a patch with tests and examples Pierre! Please commit.

1548_r1790_A1.patch brings a little change to pgiraud's patch. The styles-unique.html is modified not to use the strings "Unknown", "Update", "Delete" and "Create" as keys in the lookup object. The constants OpenLayers.State.UNKNOWN and friends must be used instead.

You're right, your changes to my patch are worth. I just didn't find the way to write this down.

(In [7216]) context can now be given as argument in StyleMap.addUniqueValueRules() this, for example, allows user to access to properties that are not part of the feature attributes. r=elemoine (closes #1548)