256 lines
9.2 KiB
JavaScript
256 lines
9.2 KiB
JavaScript
/* Copyright (c) 2006-2012 by OpenLayers Contributors (see authors.txt for
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* full list of contributors). Published under the Clear BSD license.
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* 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/Geometry/Collection.js
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* @requires OpenLayers/Geometry/LinearRing.js
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*/
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/**
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* Class: OpenLayers.Geometry.Polygon
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* Polygon is a collection of Geometry.LinearRings.
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*
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* Inherits from:
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* - <OpenLayers.Geometry.Collection>
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* - <OpenLayers.Geometry>
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*/
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OpenLayers.Geometry.Polygon = OpenLayers.Class(
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OpenLayers.Geometry.Collection, {
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/**
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* Property: componentTypes
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* {Array(String)} An array of class names representing the types of
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* components that the collection can include. A null value means the
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* component types are not restricted.
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*/
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componentTypes: ["OpenLayers.Geometry.LinearRing"],
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/**
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* Constructor: OpenLayers.Geometry.Polygon
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* Constructor for a Polygon geometry.
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* The first ring (this.component[0])is the outer bounds of the polygon and
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* all subsequent rings (this.component[1-n]) are internal holes.
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*
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*
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* Parameters:
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* components - {Array(<OpenLayers.Geometry.LinearRing>)}
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*/
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/**
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* APIMethod: getArea
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* Calculated by subtracting the areas of the internal holes from the
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* area of the outer hole.
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*
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* Returns:
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* {float} The area of the geometry
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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 > 0)) {
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area += Math.abs(this.components[0].getArea());
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for (var i=1, len=this.components.length; i<len; i++) {
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area -= Math.abs(this.components[i].getArea());
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}
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}
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return area;
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},
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/**
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* APIMethod: getGeodesicArea
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* Calculate the approximate area of the polygon were it projected onto
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* the earth.
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*
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* Parameters:
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* projection - {<OpenLayers.Projection>} The spatial reference system
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* for the geometry coordinates. If not provided, Geographic/WGS84 is
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* assumed.
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*
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* Reference:
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* Robert. G. Chamberlain and William H. Duquette, "Some Algorithms for
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* Polygons on a Sphere", JPL Publication 07-03, Jet Propulsion
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* Laboratory, Pasadena, CA, June 2007 http://trs-new.jpl.nasa.gov/dspace/handle/2014/40409
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*
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* Returns:
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* {float} The approximate geodesic area of the polygon in square meters.
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*/
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getGeodesicArea: function(projection) {
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var area = 0.0;
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if(this.components && (this.components.length > 0)) {
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area += Math.abs(this.components[0].getGeodesicArea(projection));
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for(var i=1, len=this.components.length; i<len; i++) {
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area -= Math.abs(this.components[i].getGeodesicArea(projection));
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}
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}
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return area;
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},
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/**
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* Method: containsPoint
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* Test if a point is inside a polygon. Points on a polygon edge are
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* considered inside.
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*
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* Parameters:
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* point - {<OpenLayers.Geometry.Point>}
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*
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* Returns:
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* {Boolean | Number} The point is inside the polygon. Returns 1 if the
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* point is on an edge. Returns boolean otherwise.
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*/
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containsPoint: function(point) {
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var numRings = this.components.length;
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var contained = false;
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if(numRings > 0) {
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// check exterior ring - 1 means on edge, boolean otherwise
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contained = this.components[0].containsPoint(point);
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if(contained !== 1) {
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if(contained && numRings > 1) {
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// check interior rings
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var hole;
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for(var i=1; i<numRings; ++i) {
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hole = this.components[i].containsPoint(point);
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if(hole) {
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if(hole === 1) {
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// on edge
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contained = 1;
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} else {
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// in hole
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contained = false;
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}
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break;
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}
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}
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}
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}
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}
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return contained;
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},
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/**
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* APIMethod: intersects
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* Determine if the input geometry intersects this one.
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*
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* Parameters:
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* geometry - {<OpenLayers.Geometry>} Any type of geometry.
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*
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* Returns:
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* {Boolean} The input geometry intersects this one.
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*/
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intersects: function(geometry) {
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var intersect = false;
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var i, len;
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if(geometry.CLASS_NAME == "OpenLayers.Geometry.Point") {
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intersect = this.containsPoint(geometry);
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} else if(geometry.CLASS_NAME == "OpenLayers.Geometry.LineString" ||
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geometry.CLASS_NAME == "OpenLayers.Geometry.LinearRing") {
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// check if rings/linestrings intersect
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for(i=0, len=this.components.length; i<len; ++i) {
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intersect = geometry.intersects(this.components[i]);
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if(intersect) {
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break;
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}
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}
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if(!intersect) {
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// check if this poly contains points of the ring/linestring
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for(i=0, len=geometry.components.length; i<len; ++i) {
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intersect = this.containsPoint(geometry.components[i]);
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if(intersect) {
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break;
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}
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}
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}
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} else {
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for(i=0, len=geometry.components.length; i<len; ++ i) {
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intersect = this.intersects(geometry.components[i]);
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if(intersect) {
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break;
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}
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}
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}
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// check case where this poly is wholly contained by another
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if(!intersect && geometry.CLASS_NAME == "OpenLayers.Geometry.Polygon") {
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// exterior ring points will be contained in the other geometry
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var ring = this.components[0];
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for(i=0, len=ring.components.length; i<len; ++i) {
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intersect = geometry.containsPoint(ring.components[i]);
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if(intersect) {
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break;
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}
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}
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}
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return intersect;
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},
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/**
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* APIMethod: distanceTo
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* Calculate the closest distance between two geometries (on the x-y plane).
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*
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* Parameters:
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* geometry - {<OpenLayers.Geometry>} The target geometry.
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* options - {Object} Optional properties for configuring the distance
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* calculation.
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*
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* Valid options:
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* details - {Boolean} Return details from the distance calculation.
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* Default is false.
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* edge - {Boolean} Calculate the distance from this geometry to the
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* nearest edge of the target geometry. Default is true. If true,
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* calling distanceTo from a geometry that is wholly contained within
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* the target will result in a non-zero distance. If false, whenever
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* geometries intersect, calling distanceTo will return 0. If false,
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* details cannot be returned.
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*
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* Returns:
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* {Number | Object} The distance between this geometry and the target.
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* If details is true, the return will be an object with distance,
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* x0, y0, x1, and y1 properties. The x0 and y0 properties represent
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* the coordinates of the closest point on this geometry. The x1 and y1
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* properties represent the coordinates of the closest point on the
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* target geometry.
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*/
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distanceTo: function(geometry, options) {
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var edge = !(options && options.edge === false);
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var result;
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// this is the case where we might not be looking for distance to edge
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if(!edge && this.intersects(geometry)) {
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result = 0;
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} else {
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result = OpenLayers.Geometry.Collection.prototype.distanceTo.apply(
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this, [geometry, options]
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);
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}
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return result;
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},
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CLASS_NAME: "OpenLayers.Geometry.Polygon"
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});
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/**
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* APIMethod: createRegularPolygon
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* Create a regular polygon around a radius. Useful for creating circles
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* and the like.
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*
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* Parameters:
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* origin - {<OpenLayers.Geometry.Point>} center of polygon.
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* radius - {Float} distance to vertex, in map units.
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* sides - {Integer} Number of sides. 20 approximates a circle.
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* rotation - {Float} original angle of rotation, in degrees.
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*/
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OpenLayers.Geometry.Polygon.createRegularPolygon = function(origin, radius, sides, rotation) {
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var angle = Math.PI * ((1/sides) - (1/2));
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if(rotation) {
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angle += (rotation / 180) * Math.PI;
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}
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var rotatedAngle, x, y;
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var points = [];
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for(var i=0; i<sides; ++i) {
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rotatedAngle = angle + (i * 2 * Math.PI / sides);
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x = origin.x + (radius * Math.cos(rotatedAngle));
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y = origin.y + (radius * Math.sin(rotatedAngle));
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points.push(new OpenLayers.Geometry.Point(x, y));
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}
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var ring = new OpenLayers.Geometry.LinearRing(points);
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return new OpenLayers.Geometry.Polygon([ring]);
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};
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