bounds.js

用来在地图上做操作GIS,在地图上做标记

/* Copyright (c) 2006-2007 MetaCarta, Inc., published under the BSD license.
 * See http://svn.openlayers.org/trunk/openlayers/release-license.txt 
 * for the full text of the license. */

/**
 * Class: OpenLayers.Bounds
 * Instances of this class represent bounding boxes.  Data stored as left,
 * bottom, right, top floats. All values are initialized to null, however,
 * you should make sure you set them before using the bounds for anything.
 * 
 * Possible use case:
 * > bounds = new OpenLayers.Bounds();
 * > bounds.extend(new OpenLayers.LonLat(4,5));
 * > bounds.extend(new OpenLayers.LonLat(5,6));
 * > bounds.toBBOX(); // returns 4,5,5,6
 */
OpenLayers.Bounds = OpenLayers.Class({

    /**
     * Property: left
     * {Number}
     */
    left: null,

    /**
     * Property: bottom
     * {Number}
     */
    bottom: null,

    /**
     * Property: right
     * {Number}
     */
    right: null,

    /**
     * Property: top
     * {Number}
     */
    top: null,    

    /**
     * Constructor: OpenLayers.Bounds
     * Construct a new bounds object.
     *
     * Parameters:
     * left - {Number} The left bounds of the box.  Note that for width
     *        calculations, this is assumed to be less than the right value.
     * bottom - {Number} The bottom bounds of the box.  Note that for height
     *          calculations, this is assumed to be more than the top value.
     * right - {Number} The right bounds.
     * top - {Number} The top bounds.
     */
    initialize: function(left, bottom, right, top) {
        if (left != null) {
            this.left = parseFloat(left);
        }
        if (bottom != null) {
            this.bottom = parseFloat(bottom);
        }
        if (right != null) {
            this.right = parseFloat(right);
        }
        if (top != null) {
            this.top = parseFloat(top);
        }
    },

    /**
     * Method: clone
     * Create a cloned instance of this bounds.
     *
     * Returns:
     * {<OpenLayers.Bounds>} A fresh copy of the bounds
     */
    clone:function() {
        return new OpenLayers.Bounds(this.left, this.bottom, 
                                     this.right, this.top);
    },

    /**
     * Method: equals
     * Test a two bounds for equivalence.
     *
     * Parameters:
     * bounds - {<OpenLayers.Bounds>}
     *
     * Returns:
     * {Boolean} The passed-in bounds object has the same left,
     *           right, top, bottom components as this.  Note that if bounds 
     *           passed in is null, returns false.
     */
    equals:function(bounds) {
        var equals = false;
        if (bounds != null) {
            equals = ((this.left == bounds.left) && 
                      (this.right == bounds.right) &&
                      (this.top == bounds.top) && 
                      (this.bottom == bounds.bottom));
        }
        return equals;
    },

    /** 
     * APIMethod: toString
     * 
     * Returns:
     * {String} String representation of bounds object. 
     *          (ex.<i>"left-bottom=(5,42) right-top=(10,45)"</i>)
     */
    toString:function() {
        return ( "left-bottom=(" + this.left + "," + this.bottom + ")"
                 + " right-top=(" + this.right + "," + this.top + ")" );
    },

    /**
     * APIMethod: toArray
     *
     * Returns:
     * {Array} array of left, bottom, right, top
     */
    toArray: function() {
        return [this.left, this.bottom, this.right, this.top];
    },    

    /** 
     * APIMethod: toBBOX
     * 
     * Parameters:
     * decimal - {Integer} How many significant digits in the bbox coords?
     *                     Default is 6
     * 
     * Returns:
     * {String} Simple String representation of bounds object.
     *          (ex. <i>"5,42,10,45"</i>)
     */
    toBBOX:function(decimal) {
        if (decimal== null) {
            decimal = 6; 
        }
        var mult = Math.pow(10, decimal);
        var bbox = Math.round(this.left * mult) / mult + "," + 
                   Math.round(this.bottom * mult) / mult + "," + 
                   Math.round(this.right * mult) / mult + "," + 
                   Math.round(this.top * mult) / mult;

        return bbox;
    },
    
    /**
     * APIMethod: getWidth
     * 
     * Returns:
     * {Float} The width of the bounds
     */
    getWidth:function() {
        return (this.right - this.left);
    },

    /**
     * APIMethod: getHeight
     * 
     * Returns:
     * {Float} The height of the bounds (top minus bottom).
     */
    getHeight:function() {
        return (this.top - this.bottom);
    },

    /**
     * APIMethod: getSize
     * 
     * Returns:
     * {<OpenLayers.Size>} The size of the box.
     */
    getSize:function() {
        return new OpenLayers.Size(this.getWidth(), this.getHeight());
    },

    /**
     * APIMethod: getCenterPixel
     * 
     * Returns:
     * {<OpenLayers.Pixel>} The center of the bounds in pixel space.
     */
    getCenterPixel:function() {
        return new OpenLayers.Pixel( (this.left + this.right) / 2,
                                     (this.bottom + this.top) / 2);
    },

    /**
     * APIMethod: getCenterLonLat
     * 
     * Returns:
     * {<OpenLayers.LonLat>} The center of the bounds in map space.
     */
    getCenterLonLat:function() {
        return new OpenLayers.LonLat( (this.left + this.right) / 2,
                                      (this.bottom + this.top) / 2);
    },

    /**
     * APIMethod: add
     * 
     * Parameters:
     * x - {Float}
     * y - {Float}
     * 
     * Returns:
     * {<OpenLayers.Bounds>} A new bounds whose coordinates are the same as
     *     this, but shifted by the passed-in x and y values.
     */
    add:function(x, y) {
        if ( (x == null) || (y == null) ) {
            var msg = "You must pass both x and y values to the add function.";
            OpenLayers.Console.error(msg);
            return null;
        }
        return new OpenLayers.Bounds(this.left + x, this.bottom + y,
                                     this.right + x, this.top + y);
    },
    
    /**
     * APIMethod: extend
     * Extend the bounds to include the point, lonlat, or bounds specified.
     *     Note, this function assumes that left < right and bottom < top.
     * 
     * Parameters: 
     * object - {Object} Can be LonLat, Point, or Bounds
     */
    extend:function(object) {
        var bounds = null;
        if (object) {
            switch(object.CLASS_NAME) {
                case "OpenLayers.LonLat":    
                    bounds = new OpenLayers.Bounds(object.lon, object.lat,
                                                    object.lon, object.lat);
                    break;
                case "OpenLayers.Geometry.Point":
                    bounds = new OpenLayers.Bounds(object.x, object.y,
                                                    object.x, object.y);
                    break;
                    
                case "OpenLayers.Bounds":    
                    bounds = object;
                    break;
            }
    
            if (bounds) {
                if ( (this.left == null) || (bounds.left < this.left)) {
                    this.left = bounds.left;
                }
                if ( (this.bottom == null) || (bounds.bottom < this.bottom) ) {
                    this.bottom = bounds.bottom;
                } 
                if ( (this.right == null) || (bounds.right > this.right) ) {
                    this.right = bounds.right;
                }
                if ( (this.top == null) || (bounds.top > this.top) ) { 
                    this.top = bounds.top;
                }
            }
        }
    },

    /**
     * APIMethod: containsLonLat
     * 
     * Parameters:
     * ll - {<OpenLayers.LonLat>}
     * inclusive - {Boolean} Whether or not to include the border.
     *     Default is true.
     *
     * Returns:
     * {Boolean} The passed-in lonlat is within this bounds.
     */
    containsLonLat:function(ll, inclusive) {