layerswitcher.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/Control.js
 * 
 * Class: OpenLayers.Control.LayerSwitcher
 *
 * Inherits from:
 *  - <OpenLayers.Control>
 */
OpenLayers.Control.LayerSwitcher = 
  OpenLayers.Class(OpenLayers.Control, {

    /**  
     * Property: activeColor
     * {String}
     */
    activeColor: "darkblue",
    
    /**  
     * Property: layerStates 
     * {Array(Object)} Basically a copy of the "state" of the map's layers 
     *     the last time the control was drawn. We have this in order to avoid
     *     unnecessarily redrawing the control.
     */
    layerStates: null,
    

  // DOM Elements
  
    /**
     * Property: layersDiv
     * {DOMElement} 
     */
    layersDiv: null,
    
    /** 
     * Property: baseLayersDiv
     * {DOMElement}
     */
    baseLayersDiv: null,

    /** 
     * Property: baseLayers
     * {Array(<OpenLayers.Layer>)}
     */
    baseLayers: null,
    
    
    /** 
     * Property: dataLbl
     * {DOMElement} 
     */
    dataLbl: null,
    
    /** 
     * Property: dataLayersDiv
     * {DOMElement} 
     */
    dataLayersDiv: null,

    /** 
     * Property: dataLayers
     * {Array(<OpenLayers.Layer>)} 
     */
    dataLayers: null,


    /** 
     * Property: minimizeDiv
     * {DOMElement} 
     */
    minimizeDiv: null,

    /** 
     * Property: maximizeDiv
     * {DOMElement} 
     */
    maximizeDiv: null,
    
    /**
     * APIProperty: ascending
     * {Boolean} 
     */
    ascending: true,
 
    /**
     * Constructor: OpenLayers.Control.LayerSwitcher
     * 
     * Parameters:
     * options - {Object}
     */
    initialize: function(options) {
        OpenLayers.Control.prototype.initialize.apply(this, arguments);
        this.layerStates = [];
    },

    /**
     * APIMethod: destroy 
     */    
    destroy: function() {
        
        OpenLayers.Event.stopObservingElement(this.div);

        OpenLayers.Event.stopObservingElement(this.minimizeDiv);
        OpenLayers.Event.stopObservingElement(this.maximizeDiv);

        //clear out layers info and unregister their events 
        this.clearLayersArray("base");
        this.clearLayersArray("data");
        
        this.map.events.unregister("addlayer", this, this.redraw);
        this.map.events.unregister("changelayer", this, this.redraw);
        this.map.events.unregister("removelayer", this, this.redraw);
        this.map.events.unregister("changebaselayer", this, this.redraw);
        
        OpenLayers.Control.prototype.destroy.apply(this, arguments);
    },

    /** 
     * Method: setMap
     *
     * Properties:
     * map - {<OpenLayers.Map>} 
     */
    setMap: function(map) {
        OpenLayers.Control.prototype.setMap.apply(this, arguments);

        this.map.events.register("addlayer", this, this.redraw);
        this.map.events.register("changelayer", this, this.redraw);
        this.map.events.register("removelayer", this, this.redraw);
        this.map.events.register("changebaselayer", this, this.redraw);
    },

    /**
     * Method: draw
     *
     * Returns:
     * {DOMElement} A reference to the DIV DOMElement containing the 
     *     switcher tabs.
     */  
    draw: function() {
        OpenLayers.Control.prototype.draw.apply(this);

        // create layout divs
        this.loadContents();

        // set mode to minimize
        if(!this.outsideViewport) {
            this.minimizeControl();
        }

        // populate div with current info
        this.redraw();    

        return this.div;
    },

    /** 
     * Method: clearLayersArray
     * User specifies either "base" or "data". we then clear all the
     *     corresponding listeners, the div, and reinitialize a new array.
     * 
     * Parameters:
     * layersType - {String}  
     */
    clearLayersArray: function(layersType) {
        var layers = this[layersType + "Layers"];
        if (layers) {
            for(var i=0; i < layers.length; i++) {
                var layer = layers[i];
                OpenLayers.Event.stopObservingElement(layer.inputElem);
                OpenLayers.Event.stopObservingElement(layer.labelSpan);
            }
        }
        this[layersType + "LayersDiv"].innerHTML = "";
        this[layersType + "Layers"] = [];
    },


    /**
     * Method: checkRedraw
     * Checks if the layer state has changed since the last redraw() call.
     * 
     * Returns:
     * {Boolean} The layer state changed since the last redraw() call. 
     */
    checkRedraw: function() {
        var redraw = false;
        if ( !this.layerStates.length ||
             (this.map.layers.length != this.layerStates.length) ) {
            redraw = true;
        } else {
            for (var i=0; i < this.layerStates.length; i++) {
                var layerState = this.layerStates[i];
                var layer = this.map.layers[i];
                if ( (layerState.name != layer.name) || 
                     (layerState.inRange != layer.inRange) || 
                     (layerState.id != layer.id) || 
                     (layerState.visibility != layer.visibility) ) {
                    redraw = true;
                    break;
                }    
            }
        }    
        return redraw;
    },
    
    /** 
     * Method: redraw
     * Goes through and takes the current state of the Map and rebuilds the
     *     control to display that state. Groups base layers into a 
     *     radio-button group and lists each data layer with a checkbox.
     *
     * Returns: 
     * {DOMElement} A reference to the DIV DOMElement containing the control
     */  
    redraw: function() {
        //if the state hasn't changed since last redraw, no need 
        // to do anything. Just return the existing div.
        if (!this.checkRedraw()) { 
            return this.div; 
        } 

        //clear out previous layers 
        this.clearLayersArray("base");
        this.clearLayersArray("data");
        
        var containsOverlays = false;
        var containsBaseLayers = false;
        
        // Save state -- for checking layer if the map state changed.
        // We save this before redrawing, because in the process of redrawing
        // we will trigger more visibility changes, and we want to not redraw
        // and enter an infinite loop.
        this.layerStates = new Array(this.map.layers.length);
        for (var i = 0; i < this.map.layers.length; i++) {
            var layer = this.map.layers[i];
            this.layerStates[i] = {
                'name': layer.name, 
                'visibility': layer.visibility,
                'inRange': layer.inRange,
                'id': layer.id
            };
        }    

        var layers = this.map.layers.slice();
        if (!this.ascending) { layers.reverse(); }
        for( var i = 0; i < layers.length; i++) {
            var layer = layers[i];
            var baseLayer = layer.isBaseLayer;

            if (layer.displayInLayerSwitcher) {

                if (baseLayer) {
                    containsBaseLayers = true;
                } else {
                    containsOverlays = true;
                }    

                // only check a baselayer if it is *the* baselayer, check data
                //  layers if they are visible
                var checked = (baseLayer) ? (layer == this.map.baseLayer)
                                          : layer.getVisibility();
    
                // create input element
                var inputElem = document.createElement("input");
                inputElem.id = "input_" + layer.name;
                inputElem.name = (baseLayer) ? "baseLayers" : layer.name;
                inputElem.type = (baseLayer) ? "radio" : "checkbox";
                inputElem.value = layer.name;
                inputElem.checked = checked;
                inputElem.defaultChecked = checked;

                if (!baseLayer && !layer.inRange) {
                    inputElem.disabled = true;
                }
                var context = {
                    'inputElem': inputElem,
                    'layer': layer,
                    'layerSwitcher': this
                }
                OpenLayers.Event.observe(inputElem, "mouseup", 
                    OpenLayers.Function.bindAsEventListener(this.onInputClick,
                                                            context)
                );
                
                // create span
                var labelSpan = document.createElement("span");
                if (!baseLayer && !layer.inRange) {
                    labelSpan.style.color = "gray";
                }
                labelSpan.innerHTML = layer.name;
                labelSpan.style.verticalAlign = (baseLayer) ? "bottom" 
                                                            : "baseline";
                OpenLayers.Event.observe(labelSpan, "click", 
                    OpenLayers.Function.bindAsEventListener(this.onInputClick,
                                                            context)
                );
                // create line break
                var br = document.createElement("br");
    
                
                var groupArray = (baseLayer) ? this.baseLayers
                                             : this.dataLayers;
                groupArray.push({
                    'layer': layer,
                    'inputElem': inputElem,
                    'labelSpan': labelSpan
                });