7218fe6ea8
git-svn-id: http://svn.openlayers.org/trunk/openlayers@2901 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
114 lines
3.9 KiB
JavaScript
114 lines
3.9 KiB
JavaScript
/* Copyright (c) 2006 MetaCarta, Inc., published under a modified BSD license.
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* See http://svn.openlayers.org/trunk/openlayers/repository-license.txt
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* for the full text of the license. */
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/**
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* @class
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*
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* A Linear Ring is a special LineString which is closed. It closes itself
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* automatically on every addPoint/removePoint by adding a copy of the first
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* point as the last point.
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*
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* Also, as it is the first in the line family to close itself, a getArea()
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* function is defined to calculate the enclosed area of the linearRing
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*
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* @requires OpenLayers/Geometry/LineString.js
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*/
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OpenLayers.Geometry.LinearRing = OpenLayers.Class.create();
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OpenLayers.Geometry.LinearRing.prototype =
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OpenLayers.Class.inherit(OpenLayers.Geometry.LineString, {
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/**
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* @constructor
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*
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* @param {Array(OpenLayers.Geometry.Point)} points
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*/
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initialize: function(points) {
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OpenLayers.Geometry.LineString.prototype.initialize.apply(this,
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arguments);
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},
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/**
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* @returns An exact clone of this OpenLayers.Geometry.LinearRing
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* @type OpenLayers.Geometry.LinearRing
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*/
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clone: function (obj) {
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if (obj == null) {
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obj = new OpenLayers.Geometry.LinearRing();
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}
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for (var i = 0; i < this.components.length; i++) {
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obj.addComponent(this.components[i].clone());
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}
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return obj;
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},
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/**
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* Adds a point to geometry components
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*
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* @param {OpenLayers.Geometry.Point} point
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* @param {int} index Index into the array to insert the component
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*/
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addComponent: function(point, index) {
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//remove last point
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var lastPoint = this.components[this.components.length-1];
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OpenLayers.Geometry.Curve.prototype.removeComponent.apply(this,
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[lastPoint]);
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//add our point
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OpenLayers.Geometry.LineString.prototype.addComponent.apply(this,
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arguments);
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//append copy of first point
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var firstPoint = this.components[0];
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OpenLayers.Geometry.Curve.prototype.addComponent.apply(this,
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[firstPoint.clone()]);
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},
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/**
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* Removes a point from geometry components
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*
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* @param {OpenLayers.Geometry.Point} point
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*/
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removeComponent: function(point) {
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if (this.components.length > 4) {
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//remove last point
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var lastPoint = this.components[this.components.length-1];
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OpenLayers.Geometry.Curve.prototype.removeComponent.apply(this,
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[lastPoint]);
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//remove our point
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OpenLayers.Geometry.LineString.prototype.removeComponent.apply(this,
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arguments);
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//append copy of first point
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var firstPoint = this.components[0];
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OpenLayers.Geometry.Curve.prototype.addComponent.apply(this,
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[firstPoint.clone()]);
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}
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},
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/** Note: The area is positive if the ring is oriented CW, otherwise
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* it will be negative.
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*
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* @returns The signed area for a ring.
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* @type float
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*/
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getArea: function() {
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var area = 0.0;
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if ( this.components && (this.components.length > 2)) {
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var sum = 0.0;
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for (var i = 0; i < this.components.length - 1; i++) {
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var b = this.components[i];
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var c = this.components[i+1];
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sum += (b.x + c.x) * (c.y - b.y);
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}
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area = - sum / 2.0;
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}
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return area;
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},
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/** @final @type String */
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CLASS_NAME: "OpenLayers.Geometry.LinearRing"
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});
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