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/Collection.js |
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8 | * @requires OpenLayers/Geometry/LinearRing.js |
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9 | */ |
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10 | |
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11 | /** |
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12 | * Class: OpenLayers.Geometry.Polygon |
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13 | * Polygon is a collection of Geometry.LinearRings. |
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14 | * |
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15 | * Inherits from: |
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16 | * - <OpenLayers.Geometry.Collection> |
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17 | * - <OpenLayers.Geometry> |
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18 | */ |
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19 | OpenLayers.Geometry.Polygon = OpenLayers.Class( |
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20 | OpenLayers.Geometry.Collection, { |
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21 | |
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22 | /** |
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23 | * Property: componentTypes |
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24 | * {Array(String)} An array of class names representing the types of |
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25 | * components that the collection can include. A null value means the |
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26 | * component types are not restricted. |
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27 | */ |
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28 | componentTypes: ["OpenLayers.Geometry.LinearRing"], |
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29 | |
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30 | /** |
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31 | * Constructor: OpenLayers.Geometry.Polygon |
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32 | * Constructor for a Polygon geometry. |
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33 | * The first ring (this.component[0])is the outer bounds of the polygon and |
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34 | * all subsequent rings (this.component[1-n]) are internal holes. |
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35 | * |
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36 | * |
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37 | * Parameters: |
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38 | * components - {Array(<OpenLayers.Geometry.LinearRing>)} |
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39 | */ |
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40 | initialize: function(components) { |
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41 | OpenLayers.Geometry.Collection.prototype.initialize.apply(this, |
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42 | arguments); |
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43 | }, |
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44 | |
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45 | /** |
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46 | * APIMethod: getArea |
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47 | * Calculated by subtracting the areas of the internal holes from the |
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48 | * area of the outer hole. |
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49 | * |
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50 | * Returns: |
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51 | * {float} The area of the geometry |
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52 | */ |
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53 | getArea: function() { |
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54 | var area = 0.0; |
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55 | if ( this.components && (this.components.length > 0)) { |
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56 | area += Math.abs(this.components[0].getArea()); |
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57 | for (var i=1, len=this.components.length; i<len; i++) { |
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58 | area -= Math.abs(this.components[i].getArea()); |
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59 | } |
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60 | } |
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61 | return area; |
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62 | }, |
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63 | |
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64 | /** |
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65 | * APIMethod: getGeodesicArea |
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66 | * Calculate the approximate area of the polygon were it projected onto |
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67 | * the earth. |
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68 | * |
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69 | * Parameters: |
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70 | * projection - {<OpenLayers.Projection>} The spatial reference system |
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71 | * for the geometry coordinates. If not provided, Geographic/WGS84 is |
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72 | * assumed. |
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73 | * |
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74 | * Reference: |
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75 | * Robert. G. Chamberlain and William H. Duquette, "Some Algorithms for |
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76 | * Polygons on a Sphere", JPL Publication 07-03, Jet Propulsion |
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77 | * Laboratory, Pasadena, CA, June 2007 http://trs-new.jpl.nasa.gov/dspace/handle/2014/40409 |
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78 | * |
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79 | * Returns: |
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80 | * {float} The approximate geodesic area of the polygon in square meters. |
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81 | */ |
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82 | getGeodesicArea: function(projection) { |
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83 | var area = 0.0; |
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84 | if(this.components && (this.components.length > 0)) { |
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85 | area += Math.abs(this.components[0].getGeodesicArea(projection)); |
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86 | for(var i=1, len=this.components.length; i<len; i++) { |
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87 | area -= Math.abs(this.components[i].getGeodesicArea(projection)); |
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88 | } |
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89 | } |
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90 | return area; |
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91 | }, |
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92 | |
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93 | /** |
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94 | * Method: containsPoint |
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95 | * Test if a point is inside a polygon. Points on a polygon edge are |
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96 | * considered inside. |
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97 | * |
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98 | * Parameters: |
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99 | * point - {<OpenLayers.Geometry.Point>} |
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100 | * |
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101 | * Returns: |
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102 | * {Boolean | Number} The point is inside the polygon. Returns 1 if the |
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103 | * point is on an edge. Returns boolean otherwise. |
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104 | */ |
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105 | containsPoint: function(point) { |
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106 | var numRings = this.components.length; |
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107 | var contained = false; |
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108 | if(numRings > 0) { |
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109 | // check exterior ring - 1 means on edge, boolean otherwise |
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110 | contained = this.components[0].containsPoint(point); |
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111 | if(contained !== 1) { |
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112 | if(contained && numRings > 1) { |
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113 | // check interior rings |
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114 | var hole; |
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115 | for(var i=1; i<numRings; ++i) { |
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116 | hole = this.components[i].containsPoint(point); |
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117 | if(hole) { |
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118 | if(hole === 1) { |
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119 | // on edge |
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120 | contained = 1; |
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121 | } else { |
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122 | // in hole |
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123 | contained = false; |
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124 | } |
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125 | break; |
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126 | } |
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127 | } |
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128 | } |
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129 | } |
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130 | } |
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131 | return contained; |
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132 | }, |
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133 | |
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134 | /** |
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135 | * APIMethod: intersects |
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136 | * Determine if the input geometry intersects this one. |
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137 | * |
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138 | * Parameters: |
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139 | * geometry - {<OpenLayers.Geometry>} Any type of geometry. |
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140 | * |
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141 | * Returns: |
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142 | * {Boolean} The input geometry intersects this one. |
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143 | */ |
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144 | intersects: function(geometry) { |
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145 | var intersect = false; |
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146 | var i, len; |
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147 | if(geometry.CLASS_NAME == "OpenLayers.Geometry.Point") { |
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148 | intersect = this.containsPoint(geometry); |
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149 | } else if(geometry.CLASS_NAME == "OpenLayers.Geometry.LineString" || |
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150 | geometry.CLASS_NAME == "OpenLayers.Geometry.LinearRing") { |
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151 | // check if rings/linestrings intersect |
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152 | for(i=0, len=this.components.length; i<len; ++i) { |
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153 | intersect = geometry.intersects(this.components[i]); |
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154 | if(intersect) { |
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155 | break; |
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156 | } |
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157 | } |
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158 | if(!intersect) { |
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159 | // check if this poly contains points of the ring/linestring |
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160 | for(i=0, len=geometry.components.length; i<len; ++i) { |
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161 | intersect = this.containsPoint(geometry.components[i]); |
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162 | if(intersect) { |
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163 | break; |
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164 | } |
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165 | } |
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166 | } |
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167 | } else { |
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168 | for(i=0, len=geometry.components.length; i<len; ++ i) { |
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169 | intersect = this.intersects(geometry.components[i]); |
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170 | if(intersect) { |
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171 | break; |
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172 | } |
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173 | } |
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174 | } |
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175 | // check case where this poly is wholly contained by another |
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176 | if(!intersect && geometry.CLASS_NAME == "OpenLayers.Geometry.Polygon") { |
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177 | // exterior ring points will be contained in the other geometry |
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178 | var ring = this.components[0]; |
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179 | for(i=0, len=ring.components.length; i<len; ++i) { |
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180 | intersect = geometry.containsPoint(ring.components[i]); |
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181 | if(intersect) { |
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182 | break; |
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183 | } |
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184 | } |
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185 | } |
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186 | return intersect; |
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187 | }, |
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188 | |
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189 | /** |
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190 | * APIMethod: distanceTo |
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191 | * Calculate the closest distance between two geometries (on the x-y plane). |
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192 | * |
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193 | * Parameters: |
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194 | * geometry - {<OpenLayers.Geometry>} The target geometry. |
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195 | * options - {Object} Optional properties for configuring the distance |
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196 | * calculation. |
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197 | * |
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198 | * Valid options: |
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199 | * details - {Boolean} Return details from the distance calculation. |
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200 | * Default is false. |
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201 | * edge - {Boolean} Calculate the distance from this geometry to the |
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202 | * nearest edge of the target geometry. Default is true. If true, |
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203 | * calling distanceTo from a geometry that is wholly contained within |
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204 | * the target will result in a non-zero distance. If false, whenever |
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205 | * geometries intersect, calling distanceTo will return 0. If false, |
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206 | * details cannot be returned. |
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207 | * |
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208 | * Returns: |
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209 | * {Number | Object} The distance between this geometry and the target. |
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210 | * If details is true, the return will be an object with distance, |
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211 | * x0, y0, x1, and y1 properties. The x0 and y0 properties represent |
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212 | * the coordinates of the closest point on this geometry. The x1 and y1 |
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213 | * properties represent the coordinates of the closest point on the |
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214 | * target geometry. |
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215 | */ |
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216 | distanceTo: function(geometry, options) { |
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217 | var edge = !(options && options.edge === false); |
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218 | var result; |
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219 | // this is the case where we might not be looking for distance to edge |
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220 | if(!edge && this.intersects(geometry)) { |
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221 | result = 0; |
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222 | } else { |
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223 | result = OpenLayers.Geometry.Collection.prototype.distanceTo.apply( |
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224 | this, [geometry, options] |
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225 | ); |
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226 | } |
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227 | return result; |
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228 | }, |
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229 | |
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230 | CLASS_NAME: "OpenLayers.Geometry.Polygon" |
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231 | }); |
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232 | |
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233 | /** |
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234 | * APIMethod: createRegularPolygon |
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235 | * Create a regular polygon around a radius. Useful for creating circles |
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236 | * and the like. |
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237 | * |
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238 | * Parameters: |
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239 | * origin - {<OpenLayers.Geometry.Point>} center of polygon. |
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240 | * radius - {Float} distance to vertex, in map units. |
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241 | * sides - {Integer} Number of sides. 20 approximates a circle. |
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242 | * rotation - {Float} original angle of rotation, in degrees. |
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243 | */ |
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244 | OpenLayers.Geometry.Polygon.createRegularPolygon = function(origin, radius, sides, rotation) { |
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245 | var angle = Math.PI * ((1/sides) - (1/2)); |
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246 | if(rotation) { |
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247 | angle += (rotation / 180) * Math.PI; |
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248 | } |
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249 | var rotatedAngle, x, y; |
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250 | var points = []; |
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251 | for(var i=0; i<sides; ++i) { |
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252 | rotatedAngle = angle + (i * 2 * Math.PI / sides); |
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253 | x = origin.x + (radius * Math.cos(rotatedAngle)); |
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254 | y = origin.y + (radius * Math.sin(rotatedAngle)); |
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255 | points.push(new OpenLayers.Geometry.Point(x, y)); |
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256 | } |
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257 | var ring = new OpenLayers.Geometry.LinearRing(points); |
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258 | return new OpenLayers.Geometry.Polygon([ring]); |
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259 | }; |
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