wfs.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. */


/**
 * @requires OpenLayers/Layer/Vector.js
 * @requires OpenLayers/Layer/Markers.js
 *
 * Class: OpenLayers.Layer.WFS
 * 
 * Inherits from:
 *  - <OpenLayers.Layer.Vector>
 *  - <OpenLayers.Layer.Markers>
 */
OpenLayers.Layer.WFS = OpenLayers.Class(
  OpenLayers.Layer.Vector, OpenLayers.Layer.Markers, {

    /**
     * APIProperty: isBaseLayer
     * {Boolean} WFS layer is not a base layer by default. 
     */
    isBaseLayer: false,
    
    /**
     * Property: tile
     * {<OpenLayers.Tile.WFS>}
     */
    tile: null,    
    
    /**
     * APIProperty: ratio
     * {Float} the ratio of image/tile size to map size (this is the untiled
     *     buffer)
     */
    ratio: 2,

    /**  
     * Property: DEFAULT_PARAMS
     * {Object} Hashtable of default key/value parameters
     */
    DEFAULT_PARAMS: { service: "WFS",
                      version: "1.0.0",
                      request: "GetFeature"
                    },
    
    /** 
     * APIProperty: featureClass
     * {<OpenLayers.Feature>} If featureClass is defined, an old-style markers
     *     based WFS layer is created instead of a new-style vector layer. If
     *     sent, this should be a subclass of OpenLayers.Feature
     */
    featureClass: null,

    /**
     * Property: vectorMode
     * {Boolean} Should be calculated automatically.
     */
    vectorMode: true, 
    
    /**
     * APIProperty: encodeBBOX
     * {Boolean} Should the BBOX commas be encoded? The WMS spec says 'no', 
     *     but some services want it that way. Default false.
     */
    encodeBBOX: false,
    
    /**
     * APIProperty: extractAttributes 
     * {Boolean} Should the WFS layer parse attributes from the retrieved
     *     GML? Defaults to false. If enabled, parsing is slower, but 
     *     attributes are available in the attributes property of 
     *     layer features.
     */
    extractAttributes: false,

    /**
     * Constructor: OpenLayers.Layer.WFS
     *
     * Parameters:
     * name - {String} 
     * url - {String} 
     * params - {Object} 
     * options - {Object} Hashtable of extra options to tag onto the layer
     */
    initialize: function(name, url, params, options) {
        if (options == undefined) { options = {}; } 
        
        if (options.featureClass || 
            !OpenLayers.Layer.Vector || 
            !OpenLayers.Feature.Vector) {
            this.vectorMode = false;
        }    
        
        // Turn off error reporting, browsers like Safari may work
        // depending on the setup, and we don't want an unneccesary alert.
        OpenLayers.Util.extend(options, {'reportError': false});
        var newArguments = [];
        newArguments.push(name, options);
        OpenLayers.Layer.Vector.prototype.initialize.apply(this, newArguments);
        if (!this.renderer || !this.vectorMode) {
            this.vectorMode = false; 
            if (!options.featureClass) {
                options.featureClass = OpenLayers.Feature.WFS;
            }   
            OpenLayers.Layer.Markers.prototype.initialize.apply(this, 
                                                                newArguments);
        }
        
        if (this.params && this.params.typename && !this.options.typename) {
            this.options.typename = this.params.typename;
        }
        
        if (!this.options.geometry_column) {
            this.options.geometry_column = "the_geom";
        }    
        
        this.params = params;
        OpenLayers.Util.applyDefaults(
                       this.params, 
                       OpenLayers.Util.upperCaseObject(this.DEFAULT_PARAMS)
                       );
        this.url = url;
    },    
    

    /**
     * APIMethod: destroy
     */
    destroy: function() {
        if (this.vectorMode) {
            OpenLayers.Layer.Vector.prototype.destroy.apply(this, arguments);
        } else {    
            OpenLayers.Layer.Markers.prototype.destroy.apply(this, arguments);
        }    
    },
    
    /**
     * Method: setMap
     * 
     * Parameters:
     * map - {<OpenLayers.Map>} 
     */
    setMap: function(map) {
        if (this.vectorMode) {
            OpenLayers.Layer.Vector.prototype.setMap.apply(this, arguments);
        } else {    
            OpenLayers.Layer.Markers.prototype.setMap.apply(this, arguments);
        }    
    },
    
    /** 
     * Method: moveTo
     * 
     * Parameters:
     * bounds - {<OpenLayers.Bounds>} 
     * zoomChanged - {Boolean} 
     * dragging - {Boolean} 
     */
    moveTo:function(bounds, zoomChanged, dragging) {
        if (this.vectorMode) {
            OpenLayers.Layer.Vector.prototype.moveTo.apply(this, arguments);
        } else {
            OpenLayers.Layer.Markers.prototype.moveTo.apply(this, arguments);
        }    

        // don't load wfs features while dragging, wait for drag end
        if (dragging) {
            // TBD try to hide the vector layer while dragging
            // this.setVisibility(false);
            // this will probably help for panning performances
            return false;
        }
        
        if ( zoomChanged ) {
            if (this.vectorMode) {
                this.renderer.clear();
            }
        }
        
    //DEPRECATED - REMOVE IN 3.0
        // don't load data if current zoom level doesn't match
        if (this.options.minZoomLevel) {
            
            var err = "The minZoomLevel property is only intended for use " +
                    "with the FixedZoomLevels-descendent layers. That this " +
                    "wfs layer checks for minZoomLevel is a relic of the" +
                    "past. We cannot, however, remove it without possibly " +
                    "breaking OL based applications that may depend on it." +
                    " Therefore we are deprecating it -- the minZoomLevel " +
                    "check below will be removed at 3.0. Please instead " +
                    "use min/max resolution setting as described here: " +
                    "http://trac.openlayers.org/wiki/SettingZoomLevels";
            OpenLayers.Console.warn(err);
            
            if (this.map.getZoom() < this.options.minZoomLevel) {
                return null;
            }
        }
        
        if (bounds == null) {
            bounds = this.map.getExtent();
        }

        var firstRendering = (this.tile == null);

        //does the new bounds to which we need to move fall outside of the 
        // current tile's bounds?
        var outOfBounds = (!firstRendering &&
                           !this.tile.bounds.containsBounds(bounds));

        if ( (zoomChanged || firstRendering || (!dragging && outOfBounds))
             && this.inRange) {
            //determine new tile bounds
            var center = bounds.getCenterLonLat();
            var tileWidth = bounds.getWidth() * this.ratio;
            var tileHeight = bounds.getHeight() * this.ratio;
            var tileBounds = 
                new OpenLayers.Bounds(center.lon - (tileWidth / 2),
                                      center.lat - (tileHeight / 2),
                                      center.lon + (tileWidth / 2),
                                      center.lat + (tileHeight / 2));

            //determine new tile size
            var tileSize = this.map.getSize();
            tileSize.w = tileSize.w * this.ratio;
            tileSize.h = tileSize.h * this.ratio;

            //determine new position (upper left corner of new bounds)
            var ul = new OpenLayers.LonLat(tileBounds.left, tileBounds.top);
            var pos = this.map.getLayerPxFromLonLat(ul);

            //formulate request url string
            var url = this.getFullRequestString();
        
            var params = {BBOX: this.encodeBBOX ? tileBounds.toBBOX() 
                                                : tileBounds.toArray()};
            url += "&" + OpenLayers.Util.getParameterString(params);

            if (!this.tile) {
                this.tile = new OpenLayers.Tile.WFS(this, pos, tileBounds, 
                                                     url, tileSize);