[76] | 1 | /* Copyright (c) 2006-2010 by OpenLayers Contributors (see authors.txt for |
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| 2 | * full list of contributors). Published under the Clear BSD license. |
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| 3 | * See http://svn.openlayers.org/trunk/openlayers/license.txt for the |
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| 4 | * full text of the license. */ |
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| 5 | |
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| 6 | /** |
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| 7 | * @requires OpenLayers/Geometry/LineString.js |
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| 8 | */ |
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| 9 | |
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| 10 | /** |
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| 11 | * Class: OpenLayers.Geometry.LinearRing |
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| 12 | * |
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| 13 | * A Linear Ring is a special LineString which is closed. It closes itself |
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| 14 | * automatically on every addPoint/removePoint by adding a copy of the first |
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| 15 | * point as the last point. |
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| 16 | * |
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| 17 | * Also, as it is the first in the line family to close itself, a getArea() |
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| 18 | * function is defined to calculate the enclosed area of the linearRing |
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| 19 | * |
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| 20 | * Inherits: |
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| 21 | * - <OpenLayers.Geometry.LineString> |
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| 22 | */ |
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| 23 | OpenLayers.Geometry.LinearRing = OpenLayers.Class( |
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| 24 | OpenLayers.Geometry.LineString, { |
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| 25 | |
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| 26 | /** |
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| 27 | * Property: componentTypes |
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| 28 | * {Array(String)} An array of class names representing the types of |
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| 29 | * components that the collection can include. A null |
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| 30 | * value means the component types are not restricted. |
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| 31 | */ |
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| 32 | componentTypes: ["OpenLayers.Geometry.Point"], |
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| 33 | |
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| 34 | /** |
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| 35 | * Constructor: OpenLayers.Geometry.LinearRing |
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| 36 | * Linear rings are constructed with an array of points. This array |
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| 37 | * can represent a closed or open ring. If the ring is open (the last |
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| 38 | * point does not equal the first point), the constructor will close |
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| 39 | * the ring. If the ring is already closed (the last point does equal |
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| 40 | * the first point), it will be left closed. |
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| 41 | * |
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| 42 | * Parameters: |
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| 43 | * points - {Array(<OpenLayers.Geometry.Point>)} points |
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| 44 | */ |
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| 45 | initialize: function(points) { |
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| 46 | OpenLayers.Geometry.LineString.prototype.initialize.apply(this, |
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| 47 | arguments); |
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| 48 | }, |
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| 49 | |
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| 50 | /** |
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| 51 | * APIMethod: addComponent |
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| 52 | * Adds a point to geometry components. If the point is to be added to |
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| 53 | * the end of the components array and it is the same as the last point |
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| 54 | * already in that array, the duplicate point is not added. This has |
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| 55 | * the effect of closing the ring if it is not already closed, and |
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| 56 | * doing the right thing if it is already closed. This behavior can |
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| 57 | * be overridden by calling the method with a non-null index as the |
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| 58 | * second argument. |
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| 59 | * |
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| 60 | * Parameter: |
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| 61 | * point - {<OpenLayers.Geometry.Point>} |
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| 62 | * index - {Integer} Index into the array to insert the component |
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| 63 | * |
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| 64 | * Returns: |
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| 65 | * {Boolean} Was the Point successfully added? |
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| 66 | */ |
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| 67 | addComponent: function(point, index) { |
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| 68 | var added = false; |
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| 69 | |
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| 70 | //remove last point |
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| 71 | var lastPoint = this.components.pop(); |
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| 72 | |
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| 73 | // given an index, add the point |
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| 74 | // without an index only add non-duplicate points |
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| 75 | if(index != null || !point.equals(lastPoint)) { |
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| 76 | added = OpenLayers.Geometry.Collection.prototype.addComponent.apply(this, |
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| 77 | arguments); |
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| 78 | } |
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| 79 | |
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| 80 | //append copy of first point |
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| 81 | var firstPoint = this.components[0]; |
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| 82 | OpenLayers.Geometry.Collection.prototype.addComponent.apply(this, |
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| 83 | [firstPoint]); |
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| 84 | |
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| 85 | return added; |
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| 86 | }, |
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| 87 | |
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| 88 | /** |
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| 89 | * APIMethod: removeComponent |
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| 90 | * Removes a point from geometry components. |
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| 91 | * |
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| 92 | * Parameters: |
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| 93 | * point - {<OpenLayers.Geometry.Point>} |
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| 94 | */ |
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| 95 | removeComponent: function(point) { |
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| 96 | if (this.components.length > 4) { |
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| 97 | |
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| 98 | //remove last point |
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| 99 | this.components.pop(); |
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| 100 | |
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| 101 | //remove our point |
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| 102 | OpenLayers.Geometry.Collection.prototype.removeComponent.apply(this, |
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| 103 | arguments); |
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| 104 | //append copy of first point |
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| 105 | var firstPoint = this.components[0]; |
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| 106 | OpenLayers.Geometry.Collection.prototype.addComponent.apply(this, |
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| 107 | [firstPoint]); |
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| 108 | } |
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| 109 | }, |
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| 110 | |
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| 111 | /** |
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| 112 | * APIMethod: move |
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| 113 | * Moves a geometry by the given displacement along positive x and y axes. |
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| 114 | * This modifies the position of the geometry and clears the cached |
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| 115 | * bounds. |
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| 116 | * |
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| 117 | * Parameters: |
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| 118 | * x - {Float} Distance to move geometry in positive x direction. |
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| 119 | * y - {Float} Distance to move geometry in positive y direction. |
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| 120 | */ |
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| 121 | move: function(x, y) { |
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| 122 | for(var i = 0, len=this.components.length; i<len - 1; i++) { |
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| 123 | this.components[i].move(x, y); |
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| 124 | } |
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| 125 | }, |
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| 126 | |
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| 127 | /** |
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| 128 | * APIMethod: rotate |
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| 129 | * Rotate a geometry around some origin |
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| 130 | * |
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| 131 | * Parameters: |
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| 132 | * angle - {Float} Rotation angle in degrees (measured counterclockwise |
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| 133 | * from the positive x-axis) |
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| 134 | * origin - {<OpenLayers.Geometry.Point>} Center point for the rotation |
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| 135 | */ |
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| 136 | rotate: function(angle, origin) { |
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| 137 | for(var i=0, len=this.components.length; i<len - 1; ++i) { |
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| 138 | this.components[i].rotate(angle, origin); |
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| 139 | } |
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| 140 | }, |
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| 141 | |
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| 142 | /** |
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| 143 | * APIMethod: resize |
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| 144 | * Resize a geometry relative to some origin. Use this method to apply |
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| 145 | * a uniform scaling to a geometry. |
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| 146 | * |
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| 147 | * Parameters: |
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| 148 | * scale - {Float} Factor by which to scale the geometry. A scale of 2 |
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| 149 | * doubles the size of the geometry in each dimension |
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| 150 | * (lines, for example, will be twice as long, and polygons |
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| 151 | * will have four times the area). |
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| 152 | * origin - {<OpenLayers.Geometry.Point>} Point of origin for resizing |
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| 153 | * ratio - {Float} Optional x:y ratio for resizing. Default ratio is 1. |
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| 154 | * |
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| 155 | * Returns: |
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| 156 | * {OpenLayers.Geometry} - The current geometry. |
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| 157 | */ |
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| 158 | resize: function(scale, origin, ratio) { |
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| 159 | for(var i=0, len=this.components.length; i<len - 1; ++i) { |
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| 160 | this.components[i].resize(scale, origin, ratio); |
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| 161 | } |
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| 162 | return this; |
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| 163 | }, |
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| 164 | |
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| 165 | /** |
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| 166 | * APIMethod: transform |
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| 167 | * Reproject the components geometry from source to dest. |
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| 168 | * |
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| 169 | * Parameters: |
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| 170 | * source - {<OpenLayers.Projection>} |
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| 171 | * dest - {<OpenLayers.Projection>} |
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| 172 | * |
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| 173 | * Returns: |
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| 174 | * {<OpenLayers.Geometry>} |
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| 175 | */ |
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| 176 | transform: function(source, dest) { |
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| 177 | if (source && dest) { |
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| 178 | for (var i=0, len=this.components.length; i<len - 1; i++) { |
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| 179 | var component = this.components[i]; |
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| 180 | component.transform(source, dest); |
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| 181 | } |
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| 182 | this.bounds = null; |
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| 183 | } |
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| 184 | return this; |
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| 185 | }, |
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| 186 | |
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| 187 | /** |
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| 188 | * APIMethod: getCentroid |
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| 189 | * |
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| 190 | * Returns: |
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| 191 | * {<OpenLayers.Geometry.Point>} The centroid of the collection |
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| 192 | */ |
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| 193 | getCentroid: function() { |
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| 194 | if (this.components && (this.components.length > 2)) { |
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| 195 | var sumX = 0.0; |
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| 196 | var sumY = 0.0; |
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| 197 | for (var i = 0; i < this.components.length - 1; i++) { |
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| 198 | var b = this.components[i]; |
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| 199 | var c = this.components[i+1]; |
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| 200 | sumX += (b.x + c.x) * (b.x * c.y - c.x * b.y); |
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| 201 | sumY += (b.y + c.y) * (b.x * c.y - c.x * b.y); |
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| 202 | } |
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| 203 | var area = -1 * this.getArea(); |
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| 204 | var x = sumX / (6 * area); |
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| 205 | var y = sumY / (6 * area); |
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| 206 | return new OpenLayers.Geometry.Point(x, y); |
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| 207 | } else { |
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| 208 | return null; |
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| 209 | } |
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| 210 | }, |
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| 211 | |
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| 212 | /** |
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| 213 | * APIMethod: getArea |
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| 214 | * Note - The area is positive if the ring is oriented CW, otherwise |
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| 215 | * it will be negative. |
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| 216 | * |
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| 217 | * Returns: |
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| 218 | * {Float} The signed area for a ring. |
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| 219 | */ |
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| 220 | getArea: function() { |
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| 221 | var area = 0.0; |
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| 222 | if ( this.components && (this.components.length > 2)) { |
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| 223 | var sum = 0.0; |
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| 224 | for (var i=0, len=this.components.length; i<len - 1; i++) { |
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| 225 | var b = this.components[i]; |
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| 226 | var c = this.components[i+1]; |
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| 227 | sum += (b.x + c.x) * (c.y - b.y); |
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| 228 | } |
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| 229 | area = - sum / 2.0; |
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| 230 | } |
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| 231 | return area; |
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| 232 | }, |
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| 233 | |
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| 234 | /** |
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| 235 | * APIMethod: getGeodesicArea |
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| 236 | * Calculate the approximate area of the polygon were it projected onto |
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| 237 | * the earth. Note that this area will be positive if ring is oriented |
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| 238 | * clockwise, otherwise it will be negative. |
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| 239 | * |
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| 240 | * Parameters: |
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| 241 | * projection - {<OpenLayers.Projection>} The spatial reference system |
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| 242 | * for the geometry coordinates. If not provided, Geographic/WGS84 is |
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| 243 | * assumed. |
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| 244 | * |
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| 245 | * Reference: |
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| 246 | * Robert. G. Chamberlain and William H. Duquette, "Some Algorithms for |
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| 247 | * Polygons on a Sphere", JPL Publication 07-03, Jet Propulsion |
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| 248 | * Laboratory, Pasadena, CA, June 2007 http://trs-new.jpl.nasa.gov/dspace/handle/2014/40409 |
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| 249 | * |
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| 250 | * Returns: |
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| 251 | * {float} The approximate signed geodesic area of the polygon in square |
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| 252 | * meters. |
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| 253 | */ |
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| 254 | getGeodesicArea: function(projection) { |
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| 255 | var ring = this; // so we can work with a clone if needed |
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| 256 | if(projection) { |
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| 257 | var gg = new OpenLayers.Projection("EPSG:4326"); |
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| 258 | if(!gg.equals(projection)) { |
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| 259 | ring = this.clone().transform(projection, gg); |
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| 260 | } |
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| 261 | } |
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| 262 | var area = 0.0; |
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| 263 | var len = ring.components && ring.components.length; |
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| 264 | if(len > 2) { |
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| 265 | var p1, p2; |
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| 266 | for(var i=0; i<len-1; i++) { |
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| 267 | p1 = ring.components[i]; |
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| 268 | p2 = ring.components[i+1]; |
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| 269 | area += OpenLayers.Util.rad(p2.x - p1.x) * |
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| 270 | (2 + Math.sin(OpenLayers.Util.rad(p1.y)) + |
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| 271 | Math.sin(OpenLayers.Util.rad(p2.y))); |
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| 272 | } |
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| 273 | area = area * 6378137.0 * 6378137.0 / 2.0; |
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| 274 | } |
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| 275 | return area; |
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| 276 | }, |
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| 277 | |
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| 278 | /** |
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| 279 | * Method: containsPoint |
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| 280 | * Test if a point is inside a linear ring. For the case where a point |
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| 281 | * is coincident with a linear ring edge, returns 1. Otherwise, |
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| 282 | * returns boolean. |
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| 283 | * |
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| 284 | * Parameters: |
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| 285 | * point - {<OpenLayers.Geometry.Point>} |
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| 286 | * |
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| 287 | * Returns: |
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| 288 | * {Boolean | Number} The point is inside the linear ring. Returns 1 if |
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| 289 | * the point is coincident with an edge. Returns boolean otherwise. |
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| 290 | */ |
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| 291 | containsPoint: function(point) { |
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| 292 | var approx = OpenLayers.Number.limitSigDigs; |
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| 293 | var digs = 14; |
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| 294 | var px = approx(point.x, digs); |
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| 295 | var py = approx(point.y, digs); |
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| 296 | function getX(y, x1, y1, x2, y2) { |
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| 297 | return (((x1 - x2) * y) + ((x2 * y1) - (x1 * y2))) / (y1 - y2); |
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| 298 | } |
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| 299 | var numSeg = this.components.length - 1; |
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| 300 | var start, end, x1, y1, x2, y2, cx, cy; |
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| 301 | var crosses = 0; |
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| 302 | for(var i=0; i<numSeg; ++i) { |
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| 303 | start = this.components[i]; |
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| 304 | x1 = approx(start.x, digs); |
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| 305 | y1 = approx(start.y, digs); |
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| 306 | end = this.components[i + 1]; |
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| 307 | x2 = approx(end.x, digs); |
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| 308 | y2 = approx(end.y, digs); |
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| 309 | |
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| 310 | /** |
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| 311 | * The following conditions enforce five edge-crossing rules: |
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| 312 | * 1. points coincident with edges are considered contained; |
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| 313 | * 2. an upward edge includes its starting endpoint, and |
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| 314 | * excludes its final endpoint; |
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| 315 | * 3. a downward edge excludes its starting endpoint, and |
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| 316 | * includes its final endpoint; |
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| 317 | * 4. horizontal edges are excluded; and |
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| 318 | * 5. the edge-ray intersection point must be strictly right |
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| 319 | * of the point P. |
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| 320 | */ |
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| 321 | if(y1 == y2) { |
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| 322 | // horizontal edge |
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| 323 | if(py == y1) { |
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| 324 | // point on horizontal line |
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| 325 | if(x1 <= x2 && (px >= x1 && px <= x2) || // right or vert |
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| 326 | x1 >= x2 && (px <= x1 && px >= x2)) { // left or vert |
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| 327 | // point on edge |
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| 328 | crosses = -1; |
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| 329 | break; |
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| 330 | } |
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| 331 | } |
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| 332 | // ignore other horizontal edges |
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| 333 | continue; |
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| 334 | } |
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| 335 | cx = approx(getX(py, x1, y1, x2, y2), digs); |
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| 336 | if(cx == px) { |
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| 337 | // point on line |
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| 338 | if(y1 < y2 && (py >= y1 && py <= y2) || // upward |
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| 339 | y1 > y2 && (py <= y1 && py >= y2)) { // downward |
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| 340 | // point on edge |
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| 341 | crosses = -1; |
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| 342 | break; |
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| 343 | } |
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| 344 | } |
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| 345 | if(cx <= px) { |
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| 346 | // no crossing to the right |
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| 347 | continue; |
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| 348 | } |
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| 349 | if(x1 != x2 && (cx < Math.min(x1, x2) || cx > Math.max(x1, x2))) { |
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| 350 | // no crossing |
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| 351 | continue; |
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| 352 | } |
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| 353 | if(y1 < y2 && (py >= y1 && py < y2) || // upward |
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| 354 | y1 > y2 && (py < y1 && py >= y2)) { // downward |
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| 355 | ++crosses; |
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| 356 | } |
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| 357 | } |
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| 358 | var contained = (crosses == -1) ? |
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| 359 | // on edge |
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| 360 | 1 : |
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| 361 | // even (out) or odd (in) |
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| 362 | !!(crosses & 1); |
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| 363 | |
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| 364 | return contained; |
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| 365 | }, |
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| 366 | |
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| 367 | /** |
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| 368 | * APIMethod: intersects |
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| 369 | * Determine if the input geometry intersects this one. |
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| 370 | * |
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| 371 | * Parameters: |
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| 372 | * geometry - {<OpenLayers.Geometry>} Any type of geometry. |
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| 373 | * |
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| 374 | * Returns: |
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| 375 | * {Boolean} The input geometry intersects this one. |
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| 376 | */ |
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| 377 | intersects: function(geometry) { |
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| 378 | var intersect = false; |
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| 379 | if(geometry.CLASS_NAME == "OpenLayers.Geometry.Point") { |
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| 380 | intersect = this.containsPoint(geometry); |
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| 381 | } else if(geometry.CLASS_NAME == "OpenLayers.Geometry.LineString") { |
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| 382 | intersect = geometry.intersects(this); |
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| 383 | } else if(geometry.CLASS_NAME == "OpenLayers.Geometry.LinearRing") { |
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| 384 | intersect = OpenLayers.Geometry.LineString.prototype.intersects.apply( |
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| 385 | this, [geometry] |
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| 386 | ); |
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| 387 | } else { |
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| 388 | // check for component intersections |
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| 389 | for(var i=0, len=geometry.components.length; i<len; ++ i) { |
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| 390 | intersect = geometry.components[i].intersects(this); |
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| 391 | if(intersect) { |
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| 392 | break; |
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| 393 | } |
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| 394 | } |
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| 395 | } |
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| 396 | return intersect; |
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| 397 | }, |
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| 398 | |
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| 399 | /** |
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| 400 | * APIMethod: getVertices |
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| 401 | * Return a list of all points in this geometry. |
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| 402 | * |
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| 403 | * Parameters: |
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| 404 | * nodes - {Boolean} For lines, only return vertices that are |
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| 405 | * endpoints. If false, for lines, only vertices that are not |
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| 406 | * endpoints will be returned. If not provided, all vertices will |
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| 407 | * be returned. |
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| 408 | * |
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| 409 | * Returns: |
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| 410 | * {Array} A list of all vertices in the geometry. |
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| 411 | */ |
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| 412 | getVertices: function(nodes) { |
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| 413 | return (nodes === true) ? [] : this.components.slice(0, this.components.length-1); |
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| 414 | }, |
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| 415 | |
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| 416 | CLASS_NAME: "OpenLayers.Geometry.LinearRing" |
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| 417 | }); |
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