OpenLayers学习11-格式Format控件Control

Format,没太看懂, 应该只是个父类.
先看个大概齐, 回头看了别的类 再返回头来再补充吧

Control类只定义了一堆接口, 如初始化, GC, 使能等等.
等看到他的子类估计才能用得上这些

一:Format

//Format感觉就是个父类, 下边的子类都使用他定义的接口 
OpenLayers.Format = OpenLayers.Class({
     
    //构造需要的选项
    options: null,
     
    //对象持有一个OpenLayers.Projection, 使用 reads 或者 writes 接口
    externalProjection: null,
 
    /**
     * APIProperty: internalProjection
     * {} When passed a externalProjection and
     *     internalProjection, the format will reproject the geometries it
     *     reads or writes. The internalProjection is the projection used by
     *     the geometries which are returned by read or which are passed into
     *     write.  In order to reproject, a projection transformation function
     *     for the specified projections must be available. This support may be
     *     provided via proj4js or via a custom transformation function. See
     *     {} for more information on
     *     custom transformations.
     */
    internalProjection: null,
 
    //根据keepData配置, 存储data
    data: null,
 
    //保持最新的 read data的选项
    keepData: false,
 
    //扩展本对象, 更新选项
    initialize: function(options) {
        OpenLayers.Util.extend(this, options);
        this.options = options;
    },
     
    //GC的接口, 此父类为空
    destroy: function() {
    },
 
    //这个方法等着子类继承重写, 没继承的话直接报错 
    read: function(data) {
        throw new Error('Read not implemented.');
    },
     
    //同上
    write: function(object) {
        throw new Error('Write not implemented.');
    },
 
    CLASS_NAME: "OpenLayers.Format"
});     
 
 
//这个完全不知所云, 貌似为了拿到一个默认的Format父类
OpenLayers.Format.CSWGetRecords = function(options) {
    options = OpenLayers.Util.applyDefaults(
        options, OpenLayers.Format.CSWGetRecords.DEFAULTS
    );
    var cls = OpenLayers.Format.CSWGetRecords["v"+options.version.replace(/\./g, "_")];
    if(!cls) {
        throw "Unsupported CSWGetRecords version: " + options.version;
    }
    return new cls(options);
};
OpenLayers.Format.CSWGetRecords.DEFAULTS = {
    "version": "2.0.2"
};

二: 控件类

OpenLayers.Control = OpenLayers.Class({
 
    //分配的id
    id: null,
     
    //OpenLayers.Map, addControl的map对象
    map: null,
 
    //control的容器, 没有的话就是map
    div: null,
 
    //OpenLayers.Control.Panel用的type标记
    type: null, 
 
    //是否允许被选择 默认不许, 因为这样不影响地图操作 比如拖拽
    allowSelection: false,  
 
    //控件的css类
    displayClass: "",
     
    //tooltips字串 
    title: "",
 
    //自动激活控件, 添加到地图后, 是否自动activate
    autoActivate: false,
 
    //当前的激活状态
    active: null,
 
    //控件handler的options对象
    handlerOptions: null,
 
    //控件的handler
    handler: null,
 
    //会自动添加到OpenLayers.Events.on, 构造函数里要传入此对象
    eventListeners: null,
 
    //给控件注册事件的
    /*
     * (code)
     * control.events.register(type, obj, listener);
     * (end)
     */
    events: null,
 
    //构造 var control = new OpenLayers.Control({div: myDiv}); 
    initialize: function (options) {
        //缩短类名: olControl
        this.displayClass = 
            this.CLASS_NAME.replace("OpenLayers.", "ol").replace(/\./g, "");
         
        OpenLayers.Util.extend(this, options);//合并options
         
        this.events = new OpenLayers.Events(this);//自身持有new OpenLayers.Events(this)出来的事件对象
        if(this.eventListeners instanceof Object) {
            this.events.on(this.eventListeners);//如果传参里有eventListeners, 就用刚new出来的this.events对象on注册
        }
        //不指定id就olControl_自增id
        if (this.id == null) {
            this.id = OpenLayers.Util.createUniqueID(this.CLASS_NAME + "_");
        }
    },
 
    //GC 
    destroy: function () {
        //先gc事件, 再gc事件eventListeners
        if(this.events) {
            if(this.eventListeners) {
                this.events.un(this.eventListeners);
            }
            this.events.destroy();
            this.events = null;
        }
        this.eventListeners = null;
 
        //gc持有的handler
        if (this.handler) {
            this.handler.destroy();
            this.handler = null;
        }
        if(this.handlers) {
            for(var key in this.handlers) {
                if(this.handlers.hasOwnProperty(key) &&
                   typeof this.handlers[key].destroy == "function") {
                    this.handlers[key].destroy();
                }
            }
            this.handlers = null;
        }
        //删除对map的引用
        if (this.map) {
            this.map.removeControl(this);
            this.map = null;
        }
        //断开dom的引用
        this.div = null;
    },
 
    //持有map
    setMap: function(map) {
        this.map = map;
        if (this.handler) {
            this.handler.setMap(map);
        }
    },
   
    //渲染到指定px
    draw: function (px) {
        //没有div的话, 生成一个
        if (this.div == null) {
            this.div = OpenLayers.Util.createDiv(this.id);
            this.div.className = this.displayClass;
            if (!this.allowSelection) {
                this.div.className += " olControlNoSelect";//类名
                this.div.setAttribute("unselectable", "on", 0);//最后一个参数0查半天不知道干嘛的
                this.div.onselectstart = OpenLayers.Function.False; 
            }    
            if (this.title != "") {
                this.div.title = this.title;
            }
        }
        if (px != null) {
            //为了预防传参px改变或者被回收, 特意clone了一份
            this.position = px.clone();
        }
        //画
        this.moveTo(this.position);
        return this.div;
    },
 
    //用style.left/top 绘制在持有的div上
    moveTo: function (px) {
        if ((px != null) && (this.div != null)) {
            this.div.style.left = px.x + "px";
            this.div.style.top = px.y + "px";
        }
    },
 
    //激活控件 
    activate: function () {
        //已激活的直接返回
        if (this.active) {
            return false;
        }
        //激活控件持有的handler
        if (this.handler) {
            this.handler.activate();
        }
        this.active = true;//状态位
        if(this.map) {
            //往viewPortDiv中加一个Active类
            OpenLayers.Element.addClass(
                this.map.viewPortDiv,
                this.displayClass.replace(/ /g, "") + "Active"//去空格
            );
        }
        this.events.triggerEvent("activate");//触发activate事件
        return true;
    },
     
    //关闭控件使能
    deactivate: function () {
        //已激活的
        if (this.active) {
            if (this.handler) {
                this.handler.deactivate();//handler先关掉
            }
            this.active = false;//状态
            if(this.map) {
                //删掉Active类
                OpenLayers.Element.removeClass(
                    this.map.viewPortDiv,
                    this.displayClass.replace(/ /g, "") + "Active"
                );
            }
            this.events.triggerEvent("deactivate");//触发"deactivate"事件
            return true;
        }
        return false;
    },
 
    CLASS_NAME: "OpenLayers.Control"
});
 
//三类常量 
OpenLayers.Control.TYPE_BUTTON = 1;
OpenLayers.Control.TYPE_TOGGLE = 2;
OpenLayers.Control.TYPE_TOOL   = 3;