cc2e19d789
geometries. Thanks crschmidt for the great help with this patch, and thanks to camptocamp for the initial work on this and rcoup for creating the first patches. r=crschmidt (closes #1895) git-svn-id: http://svn.openlayers.org/trunk/openlayers@9262 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
456 lines
14 KiB
JavaScript
456 lines
14 KiB
JavaScript
/* Copyright (c) 2006-2008 MetaCarta, Inc., published under the Clear BSD
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* license. 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/Format/WKT.js
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* @requires OpenLayers/Feature/Vector.js
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*/
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/**
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* Class: OpenLayers.Geometry
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* A Geometry is a description of a geographic object. Create an instance of
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* this class with the <OpenLayers.Geometry> constructor. This is a base class,
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* typical geometry types are described by subclasses of this class.
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*/
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OpenLayers.Geometry = OpenLayers.Class({
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/**
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* Property: id
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* {String} A unique identifier for this geometry.
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*/
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id: null,
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/**
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* Property: parent
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* {<OpenLayers.Geometry>}This is set when a Geometry is added as component
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* of another geometry
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*/
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parent: null,
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/**
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* Property: bounds
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* {<OpenLayers.Bounds>} The bounds of this geometry
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*/
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bounds: null,
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/**
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* Constructor: OpenLayers.Geometry
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* Creates a geometry object.
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*/
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initialize: function() {
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this.id = OpenLayers.Util.createUniqueID(this.CLASS_NAME+ "_");
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},
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/**
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* Method: destroy
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* Destroy this geometry.
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*/
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destroy: function() {
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this.id = null;
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this.bounds = null;
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},
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/**
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* APIMethod: clone
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* Create a clone of this geometry. Does not set any non-standard
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* properties of the cloned geometry.
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*
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* Returns:
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* {<OpenLayers.Geometry>} An exact clone of this geometry.
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*/
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clone: function() {
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return new OpenLayers.Geometry();
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},
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/**
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* Set the bounds for this Geometry.
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*
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* Parameters:
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* object - {<OpenLayers.Bounds>}
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*/
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setBounds: function(bounds) {
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if (bounds) {
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this.bounds = bounds.clone();
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}
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},
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/**
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* Method: clearBounds
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* Nullify this components bounds and that of its parent as well.
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*/
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clearBounds: function() {
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this.bounds = null;
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if (this.parent) {
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this.parent.clearBounds();
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}
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},
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/**
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* Method: extendBounds
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* Extend the existing bounds to include the new bounds.
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* If geometry's bounds is not yet set, then set a new Bounds.
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*
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* Parameters:
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* newBounds - {<OpenLayers.Bounds>}
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*/
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extendBounds: function(newBounds){
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var bounds = this.getBounds();
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if (!bounds) {
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this.setBounds(newBounds);
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} else {
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this.bounds.extend(newBounds);
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}
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},
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/**
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* APIMethod: getBounds
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* Get the bounds for this Geometry. If bounds is not set, it
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* is calculated again, this makes queries faster.
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*
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* Returns:
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* {<OpenLayers.Bounds>}
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*/
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getBounds: function() {
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if (this.bounds == null) {
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this.calculateBounds();
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}
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return this.bounds;
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},
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/**
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* APIMethod: calculateBounds
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* Recalculate the bounds for the geometry.
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*/
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calculateBounds: function() {
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//
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// This should be overridden by subclasses.
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//
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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 depend on the specific geometry type.
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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 x2 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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},
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/**
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* APIMethod: getVertices
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* Return a list of all points in this geometry.
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*
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* Parameters:
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* nodes - {Boolean} For lines, only return vertices that are
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* endpoints. If false, for lines, only vertices that are not
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* endpoints will be returned. If not provided, all vertices will
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* be returned.
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*
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* Returns:
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* {Array} A list of all vertices in the geometry.
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*/
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getVertices: function(nodes) {
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},
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/**
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* Method: atPoint
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* Note - This is only an approximation based on the bounds of the
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* geometry.
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*
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* Parameters:
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* lonlat - {<OpenLayers.LonLat>}
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* toleranceLon - {float} Optional tolerance in Geometric Coords
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* toleranceLat - {float} Optional tolerance in Geographic Coords
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*
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* Returns:
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* {Boolean} Whether or not the geometry is at the specified location
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*/
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atPoint: function(lonlat, toleranceLon, toleranceLat) {
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var atPoint = false;
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var bounds = this.getBounds();
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if ((bounds != null) && (lonlat != null)) {
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var dX = (toleranceLon != null) ? toleranceLon : 0;
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var dY = (toleranceLat != null) ? toleranceLat : 0;
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var toleranceBounds =
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new OpenLayers.Bounds(this.bounds.left - dX,
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this.bounds.bottom - dY,
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this.bounds.right + dX,
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this.bounds.top + dY);
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atPoint = toleranceBounds.containsLonLat(lonlat);
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}
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return atPoint;
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},
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/**
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* Method: getLength
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* Calculate the length of this geometry. This method is defined in
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* subclasses.
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*
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* Returns:
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* {Float} The length of the collection by summing its parts
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*/
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getLength: function() {
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//to be overridden by geometries that actually have a length
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//
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return 0.0;
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},
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/**
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* Method: getArea
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* Calculate the area of this geometry. This method is defined in subclasses.
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*
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* Returns:
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* {Float} The area of the collection by summing its parts
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*/
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getArea: function() {
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//to be overridden by geometries that actually have an area
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//
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return 0.0;
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},
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/**
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* APIMethod: getCentroid
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* Calculate the centroid of this geometry. This method is defined in subclasses.
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*
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* Returns:
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* {<OpenLayers.Geometry.Point>} The centroid of the collection
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*/
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getCentroid: function() {
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return null;
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},
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/**
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* Method: toString
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* Returns the Well-Known Text representation of a geometry
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*
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* Returns:
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* {String} Well-Known Text
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*/
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toString: function() {
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return OpenLayers.Format.WKT.prototype.write(
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new OpenLayers.Feature.Vector(this)
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);
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},
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CLASS_NAME: "OpenLayers.Geometry"
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});
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/**
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* Function: OpenLayers.Geometry.fromWKT
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* Generate a geometry given a Well-Known Text string.
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*
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* Parameters:
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* wkt - {String} A string representing the geometry in Well-Known Text.
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*
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* Returns:
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* {<OpenLayers.Geometry>} A geometry of the appropriate class.
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*/
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OpenLayers.Geometry.fromWKT = function(wkt) {
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var format = arguments.callee.format;
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if(!format) {
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format = new OpenLayers.Format.WKT();
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arguments.callee.format = format;
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}
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var geom;
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var result = format.read(wkt);
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if(result instanceof OpenLayers.Feature.Vector) {
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geom = result.geometry;
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} else if(result instanceof Array) {
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var len = result.length;
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var components = new Array(len);
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for(var i=0; i<len; ++i) {
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components[i] = result[i].geometry;
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}
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geom = new OpenLayers.Geometry.Collection(components);
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}
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return geom;
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};
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/**
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* Method: OpenLayers.Geometry.segmentsIntersect
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* Determine whether two line segments intersect. Optionally calculates
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* and returns the intersection point. This function is optimized for
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* cases where seg1.x2 >= seg2.x1 || seg2.x2 >= seg1.x1. In those
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* obvious cases where there is no intersection, the function should
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* not be called.
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*
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* Parameters:
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* seg1 - {Object} Object representing a segment with properties x1, y1, x2,
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* and y2. The start point is represented by x1 and y1. The end point
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* is represented by x2 and y2. Start and end are ordered so that x1 < x2.
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* seg2 - {Object} Object representing a segment with properties x1, y1, x2,
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* and y2. The start point is represented by x1 and y1. The end point
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* is represented by x2 and y2. Start and end are ordered so that x1 < x2.
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* options - {Object} Optional properties for calculating the intersection.
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*
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* Valid options:
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* point - {Boolean} Return the intersection point. If false, the actual
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* intersection point will not be calculated. If true and the segments
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* intersect, the intersection point will be returned. If true and
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* the segments do not intersect, false will be returned. If true and
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* the segments are coincident, true will be returned.
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* tolerance - {Number} If a non-null value is provided, if the segments are
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* within the tolerance distance, this will be considered an intersection.
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* In addition, if the point option is true and the calculated intersection
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* is within the tolerance distance of an end point, the endpoint will be
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* returned instead of the calculated intersection. Further, if the
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* intersection is within the tolerance of endpoints on both segments, or
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* if two segment endpoints are within the tolerance distance of eachother
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* (but no intersection is otherwise calculated), an endpoint on the
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* first segment provided will be returned.
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*
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* Returns:
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* {Boolean | <OpenLayers.Geometry.Point>} The two segments intersect.
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* If the point argument is true, the return will be the intersection
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* point or false if none exists. If point is true and the segments
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* are coincident, return will be true (and the instersection is equal
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* to the shorter segment).
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*/
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OpenLayers.Geometry.segmentsIntersect = function(seg1, seg2, options) {
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var point = options && options.point;
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var tolerance = options && options.tolerance;
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var intersection = false;
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var x11_21 = seg1.x1 - seg2.x1;
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var y11_21 = seg1.y1 - seg2.y1;
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var x12_11 = seg1.x2 - seg1.x1;
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var y12_11 = seg1.y2 - seg1.y1;
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var y22_21 = seg2.y2 - seg2.y1;
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var x22_21 = seg2.x2 - seg2.x1;
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var d = (y22_21 * x12_11) - (x22_21 * y12_11);
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var n1 = (x22_21 * y11_21) - (y22_21 * x11_21);
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var n2 = (x12_11 * y11_21) - (y12_11 * x11_21);
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if(d == 0) {
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// parallel
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if(n1 == 0 && n2 == 0) {
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// coincident
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intersection = true;
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}
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} else {
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var along1 = n1 / d;
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var along2 = n2 / d;
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if(along1 >= 0 && along1 <= 1 && along2 >=0 && along2 <= 1) {
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// intersect
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if(!point) {
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intersection = true;
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} else {
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// calculate the intersection point
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var x = seg1.x1 + (along1 * x12_11);
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var y = seg1.y1 + (along1 * y12_11);
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intersection = new OpenLayers.Geometry.Point(x, y);
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}
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}
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}
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if(tolerance) {
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var dist;
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if(intersection) {
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if(point) {
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var segs = [seg1, seg2];
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var seg, x, y;
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// check segment endpoints for proximity to intersection
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// set intersection to first endpoint within the tolerance
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outer: for(var i=0; i<2; ++i) {
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seg = segs[i];
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for(var j=1; j<3; ++j) {
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x = seg["x" + j];
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y = seg["y" + j];
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dist = Math.sqrt(
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Math.pow(x - intersection.x, 2) +
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Math.pow(y - intersection.y, 2)
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);
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if(dist < tolerance) {
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intersection.x = x;
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intersection.y = y;
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break outer;
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}
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}
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}
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}
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} else {
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// no calculated intersection, but segments could be within
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// the tolerance of one another
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var segs = [seg1, seg2];
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var source, target, x, y, p, result;
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// check segment endpoints for proximity to intersection
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// set intersection to first endpoint within the tolerance
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outer: for(var i=0; i<2; ++i) {
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source = segs[i];
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target = segs[(i+1)%2];
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for(var j=1; j<3; ++j) {
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p = {x: source["x"+j], y: source["y"+j]};
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result = OpenLayers.Geometry.distanceToSegment(p, target);
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if(result.distance < tolerance) {
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if(point) {
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intersection = new OpenLayers.Geometry.Point(p.x, p.y);
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} else {
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intersection = true;
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}
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break outer;
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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 intersection;
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};
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/**
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* Function: OpenLayers.Geometry.distanceToSegment
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*
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* Parameters:
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* point - {Object} An object with x and y properties representing the
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* point coordinates.
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* segment - {Object} An object with x1, y1, x2, and y2 properties
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* representing endpoint coordinates.
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*
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* Returns:
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* {Object} An object with distance, x, and y properties. The distance
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* will be the shortest distance between the input point and segment.
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* The x and y properties represent the coordinates along the segment
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* where the shortest distance meets the segment.
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*/
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OpenLayers.Geometry.distanceToSegment = function(point, segment) {
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var x0 = point.x;
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var y0 = point.y;
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var x1 = segment.x1;
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var y1 = segment.y1;
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var x2 = segment.x2;
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var y2 = segment.y2;
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var dx = x2 - x1;
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var dy = y2 - y1;
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var along = ((dx * (x0 - x1)) + (dy * (y0 - y1))) /
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(Math.pow(dx, 2) + Math.pow(dy, 2));
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var x, y;
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if(along <= 0.0) {
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x = x1;
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y = y1;
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} else if(along >= 1.0) {
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x = x2;
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y = y2;
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} else {
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x = x1 + along * dx;
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y = y1 + along * dy;
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}
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return {
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distance: Math.sqrt(Math.pow(x - x0, 2) + Math.pow(y - y0, 2)),
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x: x, y: y
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};
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};
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