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/* Copyright (c) 2006-2013 by OpenLayers Contributors (see authors.txt for
* full list of contributors). Published under the 2-clause BSD license.
* See license.txt in the OpenLayers distribution or repository for the
* full text of the license. */
/**
* @requires OpenLayers/BaseTypes/Class.js
* @requires OpenLayers/Util.js
* @requires OpenLayers/Style.js
*/
/**
* Class: OpenLayers.Rule
* This class represents an SLD Rule, as being used for rule-based SLD styling.
*/
OpenLayers.Rule = OpenLayers.Class({
/**
* Property: id
* {String} A unique id for this session.
*/
id: null,
/**
* APIProperty: name
* {String} name of this rule
*/
name: null,
/**
* Property: title
* {String} Title of this rule (set if included in SLD)
*/
title: null,
/**
* Property: description
* {String} Description of this rule (set if abstract is included in SLD)
*/
description: null,
/**
* Property: context
* {Object} An optional object with properties that the rule should be
* evaluated against. If no context is specified, feature.attributes will
* be used.
*/
context: null,
/**
* Property: filter
* {<OpenLayers.Filter>} Optional filter for the rule.
*/
filter: null,
/**
* Property: elseFilter
* {Boolean} Determines whether this rule is only to be applied only if
* no other rules match (ElseFilter according to the SLD specification).
* Default is false. For instances of OpenLayers.Rule, if elseFilter is
* false, the rule will always apply. For subclasses, the else property is
* ignored.
*/
elseFilter: false,
/**
* Property: symbolizer
* {Object} Symbolizer or hash of symbolizers for this rule. If hash of
* symbolizers, keys are one or more of ["Point", "Line", "Polygon"]. The
* latter if useful if it is required to style e.g. vertices of a line
* with a point symbolizer. Note, however, that this is not implemented
* yet in OpenLayers, but it is the way how symbolizers are defined in
* SLD.
*/
symbolizer: null,
/**
* Property: symbolizers
* {Array} Collection of symbolizers associated with this rule. If
* provided at construction, the symbolizers array has precedence
* over the deprecated symbolizer property. Note that multiple
* symbolizers are not currently supported by the vector renderers.
* Rules with multiple symbolizers are currently only useful for
* maintaining elements in an SLD document.
*/
symbolizers: null,
/**
* APIProperty: minScaleDenominator
* {Number} or {String} minimum scale at which to draw the feature.
* In the case of a String, this can be a combination of text and
* propertyNames in the form "literal ${propertyName}"
*/
minScaleDenominator: null,
/**
* APIProperty: maxScaleDenominator
* {Number} or {String} maximum scale at which to draw the feature.
* In the case of a String, this can be a combination of text and
* propertyNames in the form "literal ${propertyName}"
*/
maxScaleDenominator: null,
/**
* Constructor: OpenLayers.Rule
* Creates a Rule.
*
* Parameters:
* options - {Object} An optional object with properties to set on the
* rule
*
* Returns:
* {<OpenLayers.Rule>}
*/
initialize: function(options) {
this.symbolizer = {};
OpenLayers.Util.extend(this, options);
if (this.symbolizers) {
delete this.symbolizer;
}
this.id = OpenLayers.Util.createUniqueID(this.CLASS_NAME + "_");
},
/**
* APIMethod: destroy
* nullify references to prevent circular references and memory leaks
*/
destroy: function() {
for (var i in this.symbolizer) {
this.symbolizer[i] = null;
}
this.symbolizer = null;
delete this.symbolizers;
},
/**
* APIMethod: evaluate
* evaluates this rule for a specific feature
*
* Parameters:
* feature - {<OpenLayers.Feature>} feature to apply the rule to.
*
* Returns:
* {Boolean} true if the rule applies, false if it does not.
* This rule is the default rule and always returns true.
*/
evaluate: function(feature) {
var context = this.getContext(feature);
var applies = true;
if (this.minScaleDenominator || this.maxScaleDenominator) {
var scale = feature.layer.map.getScale();
}
// check if within minScale/maxScale bounds
if (this.minScaleDenominator) {
applies = scale >= OpenLayers.Style.createLiteral(
this.minScaleDenominator, context);
}
if (applies && this.maxScaleDenominator) {
applies = scale < OpenLayers.Style.createLiteral(
this.maxScaleDenominator, context);
}
// check if optional filter applies
if(applies && this.filter) {
// feature id filters get the feature, others get the context
if(this.filter.CLASS_NAME == "OpenLayers.Filter.FeatureId") {
applies = this.filter.evaluate(feature);
} else {
applies = this.filter.evaluate(context);
}
}
return applies;
},
/**
* Method: getContext
* Gets the context for evaluating this rule
*
* Paramters:
* feature - {<OpenLayers.Feature>} feature to take the context from if
* none is specified.
*/
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;
},
/**
* APIMethod: clone
* Clones this rule.
*
* Returns:
* {<OpenLayers.Rule>} Clone of this rule.
*/
clone: function() {
var options = OpenLayers.Util.extend({}, this);
if (this.symbolizers) {
// clone symbolizers
var len = this.symbolizers.length;
options.symbolizers = new Array(len);
for (var i=0; i<len; ++i) {
options.symbolizers[i] = this.symbolizers[i].clone();
}
} else {
// clone symbolizer
options.symbolizer = {};
var value, type;
for(var key in this.symbolizer) {
value = this.symbolizer[key];
type = typeof value;
if(type === "object") {
options.symbolizer[key] = OpenLayers.Util.extend({}, value);
} else if(type === "string") {
options.symbolizer[key] = value;
}
}
}
// clone filter
options.filter = this.filter && this.filter.clone();
// clone context
options.context = this.context && OpenLayers.Util.extend({}, this.context);
return new OpenLayers.Rule(options);
},
CLASS_NAME: "OpenLayers.Rule"
});
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