Added a control for drawing geometries and returning basic metrics (length / area). Patch by tschaub, review by elemoine. (Closes #1241)
git-svn-id: http://svn.openlayers.org/trunk/openlayers@7965 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
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euzuro
246
lib/OpenLayers/Control/Measure.js
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246
lib/OpenLayers/Control/Measure.js
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/* Copyright (c) 2006-2008 MetaCarta, Inc., published under the Clear BSD
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* license. See http://svn.openlayers.org/trunk/openlayers/license.txt for the
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* full text of the license. */
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/**
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* @requires OpenLayers/Control.js
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* @requires OpenLayers/Feature/Vector.js
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*/
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/**
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* Class: OpenLayers.Control.Measure
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* Allows for drawing of features for measurements.
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*
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* Inherits from:
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* - <OpenLayers.Control>
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*/
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OpenLayers.Control.Measure = OpenLayers.Class(OpenLayers.Control, {
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/**
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* Constant: EVENT_TYPES
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* {Array(String)} Supported application event types. Register a listener
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* for a particular event with the following syntax:
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* (code)
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* control.events.register(type, obj, listener);
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* (end)
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*
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* Listeners will be called with a reference to an event object. The
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* properties of this event depends on exactly what happened.
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*
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* Supported control event types (in addition to those from <OpenLayers.Control>):
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* - *measure* Triggered when a measurement sketch is complete. Listeners
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* will receive an event with measure, units, order, and geometry
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* properties.
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* - *measurepartial* Triggered when a new point is added to the
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* measurement sketch. Listeners receive an event with measure,
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* units, order, and geometry.
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*/
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EVENT_TYPES: ['measure', 'measurepartial'],
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/**
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* APIProperty: handlerOptions
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* {Object} Used to set non-default properties on the control's handler
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*/
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handlerOptions: null,
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/**
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* Property: callbacks
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* {Object} The functions that are sent to the handler for callback
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*/
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callbacks: null,
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/**
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* Property: displaySystem
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* {String} Display system for output measurements. Supported values
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* are 'english', 'metric', and 'geographic'. Default is 'metric'.
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*/
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displaySystem: 'metric',
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/**
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* Property: displaySystemUnits
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* {Object} Units for various measurement systems. Values are arrays
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* of unit abbreviations (from OpenLayers.INCHES_PER_UNIT) in decreasing
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* order of length.
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*/
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displaySystemUnits: {
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geographic: ['dd'],
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english: ['mi', 'ft', 'in'],
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metric: ['km', 'm']
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},
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/**
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* Constructor: OpenLayers.Control.Measure
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*
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* Parameters:
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* handler - {<OpenLayers.Handler>}
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* options - {Object}
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*/
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initialize: function(handler, options) {
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// concatenate events specific to measure with those from the base
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this.EVENT_TYPES =
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OpenLayers.Control.Measure.prototype.EVENT_TYPES.concat(
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OpenLayers.Control.prototype.EVENT_TYPES
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);
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OpenLayers.Control.prototype.initialize.apply(this, [options]);
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this.callbacks = OpenLayers.Util.extend(
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{done: this.measureComplete, point: this.measurePartial},
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this.callbacks
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);
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this.handler = new handler(this, this.callbacks, this.handlerOptions);
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},
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/**
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* Method: updateHandler
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*
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* Parameters:
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* handler - {Function} One of the sketch handler constructors.
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* options - {Object} Options for the handler.
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*/
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updateHandler: function(handler, options) {
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var active = this.active;
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if(active) {
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this.deactivate();
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}
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this.handler = new handler(this, this.callbacks, options);
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if(active) {
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this.activate();
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}
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},
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/**
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* Method: measureComplete
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* Called when the measurement sketch is done.
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*
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* Parameters:
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* geometry - {<OpenLayers.Geometry>}
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*/
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measureComplete: function(geometry) {
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this.measure(geometry, "measure");
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},
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/**
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* Method: measurePartial
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* Called each time a new point is added to the measurement sketch.
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*
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* Parameters:
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* point - {<OpenLayers.Geometry.Point>} The last point added.
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* geometry - {<OpenLayers.Geometry>} The sketch geometry.
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*/
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measurePartial: function(point, geometry) {
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this.measure(geometry, "measurepartial");
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},
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/**
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* Method: measure
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*
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* Parameters:
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* geometry - {<OpenLayers.Geometry>}
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* eventType - {String}
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*/
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measure: function(geometry, eventType) {
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var stat, order;
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if(geometry.CLASS_NAME.indexOf('LineString') > -1) {
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stat = this.getBestLength(geometry);
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order = 1;
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} else {
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stat = this.getBestArea(geometry);
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order = 2;
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}
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this.events.triggerEvent(eventType, {
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measure: stat[0],
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units: stat[1],
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order: order,
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geometry: geometry
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});
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},
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/**
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* Method: getBestArea
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* Based on the <displaySystem> returns the area of a geometry.
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*
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* Parameters:
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* geometry - {<OpenLayers.Geometry>}
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*
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* Returns:
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* {Array([Float, String])} Returns a two item array containing the
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* area and the units abbreviation.
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*/
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getBestArea: function(geometry) {
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var units = this.displaySystemUnits[this.displaySystem];
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var unit, area;
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for(var i=0, len=units.length; i<len; ++i) {
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unit = units[i];
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area = this.getArea(geometry, unit);
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if(area > 1) {
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break;
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}
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}
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return [area, unit];
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},
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/**
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* Method: getArea
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*
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* Parameters:
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* geometry - {<OpenLayers.Geometry>}
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* units - {String} Unit abbreviation
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*
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* Returns:
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* {Float} The geometry area in the given units.
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*/
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getArea: function(geometry, units) {
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var area = geometry.getArea();
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var inPerDisplayUnit = OpenLayers.INCHES_PER_UNIT[units];
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if(inPerDisplayUnit) {
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var inPerMapUnit = OpenLayers.INCHES_PER_UNIT[this.map.getUnits()];
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area *= Math.pow((inPerMapUnit / inPerDisplayUnit), 2);
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}
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return area;
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},
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/**
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* Method: getBestLength
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* Based on the <displaySystem> returns the length of a geometry.
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*
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* Parameters:
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* geometry - {<OpenLayers.Geometry>}
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*
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* Returns:
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* {Array([Float, String])} Returns a two item array containing the
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* length and the units abbreviation.
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*/
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getBestLength: function(geometry) {
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var units = this.displaySystemUnits[this.displaySystem];
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var unit, length;
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for(var i=0, len=units.length; i<len; ++i) {
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unit = units[i];
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length = this.getLength(geometry, unit);
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if(length > 1) {
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break;
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}
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}
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return [length, unit];
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},
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/**
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* Method: getLength
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*
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* Parameters:
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* geometry - {<OpenLayers.Geometry>}
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* units - {String} Unit abbreviation
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*
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* Returns:
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* {Float} The geometry length in the given units.
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*/
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getLength: function(geometry, units) {
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var length = geometry.getLength();
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var inPerDisplayUnit = OpenLayers.INCHES_PER_UNIT[units];
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if(inPerDisplayUnit) {
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var inPerMapUnit = OpenLayers.INCHES_PER_UNIT[this.map.getUnits()];
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length *= (inPerMapUnit / inPerDisplayUnit);
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}
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return length;
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},
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CLASS_NAME: "OpenLayers.Control.Measure"
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});
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