--- a/labs/openlayers/lib/OpenLayers/Geometry/Polygon.js +++ b/labs/openlayers/lib/OpenLayers/Geometry/Polygon.js @@ -1,1 +1,260 @@ - +/* Copyright (c) 2006-2010 by OpenLayers Contributors (see authors.txt for + * full list of contributors). Published under the Clear BSD license. + * See http://svn.openlayers.org/trunk/openlayers/license.txt for the + * full text of the license. */ + +/** + * @requires OpenLayers/Geometry/Collection.js + * @requires OpenLayers/Geometry/LinearRing.js + */ + +/** + * Class: OpenLayers.Geometry.Polygon + * Polygon is a collection of Geometry.LinearRings. + * + * Inherits from: + * - <OpenLayers.Geometry.Collection> + * - <OpenLayers.Geometry> + */ +OpenLayers.Geometry.Polygon = OpenLayers.Class( + OpenLayers.Geometry.Collection, { + + /** + * Property: componentTypes + * {Array(String)} An array of class names representing the types of + * components that the collection can include. A null value means the + * component types are not restricted. + */ + componentTypes: ["OpenLayers.Geometry.LinearRing"], + + /** + * Constructor: OpenLayers.Geometry.Polygon + * Constructor for a Polygon geometry. + * The first ring (this.component[0])is the outer bounds of the polygon and + * all subsequent rings (this.component[1-n]) are internal holes. + * + * + * Parameters: + * components - {Array(<OpenLayers.Geometry.LinearRing>)} + */ + initialize: function(components) { + OpenLayers.Geometry.Collection.prototype.initialize.apply(this, + arguments); + }, + + /** + * APIMethod: getArea + * Calculated by subtracting the areas of the internal holes from the + * area of the outer hole. + * + * Returns: + * {float} The area of the geometry + */ + getArea: function() { + var area = 0.0; + if ( this.components && (this.components.length > 0)) { + area += Math.abs(this.components[0].getArea()); + for (var i=1, len=this.components.length; i<len; i++) { + area -= Math.abs(this.components[i].getArea()); + } + } + return area; + }, + + /** + * APIMethod: getGeodesicArea + * Calculate the approximate area of the polygon were it projected onto + * the earth. + * + * Parameters: + * projection - {<OpenLayers.Projection>} The spatial reference system + * for the geometry coordinates. If not provided, Geographic/WGS84 is + * assumed. + * + * Reference: + * Robert. G. Chamberlain and William H. Duquette, "Some Algorithms for + * Polygons on a Sphere", JPL Publication 07-03, Jet Propulsion + * Laboratory, Pasadena, CA, June 2007 http://trs-new.jpl.nasa.gov/dspace/handle/2014/40409 + * + * Returns: + * {float} The approximate geodesic area of the polygon in square meters. + */ + getGeodesicArea: function(projection) { + var area = 0.0; + if(this.components && (this.components.length > 0)) { + area += Math.abs(this.components[0].getGeodesicArea(projection)); + for(var i=1, len=this.components.length; i<len; i++) { + area -= Math.abs(this.components[i].getGeodesicArea(projection)); + } + } + return area; + }, + + /** + * Method: containsPoint + * Test if a point is inside a polygon. Points on a polygon edge are + * considered inside. + * + * Parameters: + * point - {<OpenLayers.Geometry.Point>} + * + * Returns: + * {Boolean | Number} The point is inside the polygon. Returns 1 if the + * point is on an edge. Returns boolean otherwise. + */ + containsPoint: function(point) { + var numRings = this.components.length; + var contained = false; + if(numRings > 0) { + // check exterior ring - 1 means on edge, boolean otherwise + contained = this.components[0].containsPoint(point); + if(contained !== 1) { + if(contained && numRings > 1) { + // check interior rings + var hole; + for(var i=1; i<numRings; ++i) { + hole = this.components[i].containsPoint(point); + if(hole) { + if(hole === 1) { + // on edge + contained = 1; + } else { + // in hole + contained = false; + } + break; + } + } + } + } + } + return contained; + }, + + /** + * APIMethod: intersects + * Determine if the input geometry intersects this one. + * + * Parameters: + * geometry - {<OpenLayers.Geometry>} Any type of geometry. + * + * Returns: + * {Boolean} The input geometry intersects this one. + */ + intersects: function(geometry) { + var intersect = false; + var i, len; + if(geometry.CLASS_NAME == "OpenLayers.Geometry.Point") { + intersect = this.containsPoint(geometry); + } else if(geometry.CLASS_NAME == "OpenLayers.Geometry.LineString" || + geometry.CLASS_NAME == "OpenLayers.Geometry.LinearRing") { + // check if rings/linestrings intersect + for(i=0, len=this.components.length; i<len; ++i) { + intersect = geometry.intersects(this.components[i]); + if(intersect) { + break; + } + } + if(!intersect) { + // check if this poly contains points of the ring/linestring + for(i=0, len=geometry.components.length; i<len; ++i) { + intersect = this.containsPoint(geometry.components[i]); + if(intersect) { + break; + } + } + } + } else { + for(i=0, len=geometry.components.length; i<len; ++ i) { + intersect = this.intersects(geometry.components[i]); + if(intersect) { + break; + } + } + } + // check case where this poly is wholly contained by another + if(!intersect && geometry.CLASS_NAME == "OpenLayers.Geometry.Polygon") { + // exterior ring points will be contained in the other geometry + var ring = this.components[0]; + for(i=0, len=ring.components.length; i<len; ++i) { + intersect = geometry.containsPoint(ring.components[i]); + if(intersect) { + break; + } + } + } + return intersect; + }, + + /** + * APIMethod: distanceTo + * Calculate the closest distance between two geometries (on the x-y plane). + * + * Parameters: + * geometry - {<OpenLayers.Geometry>} The target geometry. + * options - {Object} Optional properties for configuring the distance + * calculation. + * + * Valid options: + * details - {Boolean} Return details from the distance calculation. + * Default is false. + * edge - {Boolean} Calculate the distance from this geometry to the + * nearest edge of the target geometry. Default is true. If true, + * calling distanceTo from a geometry that is wholly contained within + * the target will result in a non-zero distance. If false, whenever + * geometries intersect, calling distanceTo will return 0. If false, + * details cannot be returned. + * + * Returns: + * {Number | Object} The distance between this geometry and the target. + * If details is true, the return will be an object with distance, + * x0, y0, x1, and y1 properties. The x0 and y0 properties represent + * the coordinates of the closest point on this geometry. The x1 and y1 + * properties represent the coordinates of the closest point on the + * target geometry. + */ + distanceTo: function(geometry, options) { + var edge = !(options && options.edge === false); + var result; + // this is the case where we might not be looking for distance to edge + if(!edge && this.intersects(geometry)) { + result = 0; + } else { + result = OpenLayers.Geometry.Collection.prototype.distanceTo.apply( + this, [geometry, options] + ); + } + return result; + }, + + CLASS_NAME: "OpenLayers.Geometry.Polygon" +}); + +/** + * APIMethod: createRegularPolygon + * Create a regular polygon around a radius. Useful for creating circles + * and the like. + * + * Parameters: + * origin - {<OpenLayers.Geometry.Point>} center of polygon. + * radius - {Float} distance to vertex, in map units. + * sides - {Integer} Number of sides. 20 approximates a circle. + * rotation - {Float} original angle of rotation, in degrees. + */ +OpenLayers.Geometry.Polygon.createRegularPolygon = function(origin, radius, sides, rotation) { + var angle = Math.PI * ((1/sides) - (1/2)); + if(rotation) { + angle += (rotation / 180) * Math.PI; + } + var rotatedAngle, x, y; + var points = []; + for(var i=0; i<sides; ++i) { + rotatedAngle = angle + (i * 2 * Math.PI / sides); + x = origin.x + (radius * Math.cos(rotatedAngle)); + y = origin.y + (radius * Math.sin(rotatedAngle)); + points.push(new OpenLayers.Geometry.Point(x, y)); + } + var ring = new OpenLayers.Geometry.LinearRing(points); + return new OpenLayers.Geometry.Polygon([ring]); +}; +