--- a/labs/openlayers/lib/OpenLayers/Rule.js +++ b/labs/openlayers/lib/OpenLayers/Rule.js @@ -1,1 +1,240 @@ - +/* Copyright (c) 2006-2010 by OpenLayers Contributors (see authors.txt for + * full list of contributors). Published under the Clear BSD license. + * See http://svn.openlayers.org/trunk/openlayers/license.txt for the + * full text of the license. */ + + +/** + * @requires OpenLayers/Util.js + * @requires OpenLayers/Style.js + * @requires OpenLayers/Symbolizer/Point.js + * @requires OpenLayers/Symbolizer/Line.js + * @requires OpenLayers/Symbolizer/Polygon.js + * @requires OpenLayers/Symbolizer/Text.js + * @requires OpenLayers/Symbolizer/Raster.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" +});