Event 分析f二：Ext.EvenManager 源码

/**
 * author:prk
 * date：2008-08-01
 * comment:event analyse.
 * 
 */
/*
 * Ext JS Library 2.0
 * Copyright(c) 2006-2007, Ext JS, LLC.
 * [e-mail]
 * 
 * http://extjs.com/license
 */

/**
 * @class Ext.EventManager
 * Registers event handlers that want to receive a normalized EventObject instead of the standard browser event and provides
 * several useful events directly.
 * See {@link Ext.EventObject} for more details on normalized event objects.
 * @singleton
 */
Ext.EventManager = function(){
    var docReadyEvent, docReadyProcId, docReadyState = false;
    var resizeEvent, resizeTask, textEvent, textSize;
    var E = Ext.lib.Event;
    var D = Ext.lib.Dom;

  //docReady的监听函数
    var fireDocReady = function(){
        if(!docReadyState){
        	//设定加载完成的标识
            docReadyState = true;
            Ext.isReady = true;
           
            //对于Safari，成功刚应该clearInterval
            if(docReadyProcId){
                clearInterval(docReadyProcId);
            }
            //现在到了remove DOMContentLoaded的事件监听了。
            if(Ext.isGecko || Ext.isOpera) {
                document.removeEventListener("DOMContentLoaded", fireDocReady, false);
            }
            //Ie,则remove 生成的元素。
            if(Ext.isIE){
                var defer = document.getElementById("ie-deferred-loader");
                if(defer){
                    defer.onreadystatechange = null;
                    defer.parentNode.removeChild(defer);
                }
            }
            //执行docReadyEvent中监听之后除去Listeners
            if(docReadyEvent){
                docReadyEvent.fire();
                docReadyEvent.clearListeners();
            }
        }
    };
    
     //初始化docReady
    var initDocReady = function(){
        docReadyEvent = new Ext.util.Event();
        //对于Opera、Gecko.为document的DOMContentLoaded事件注册fireDocReady监听。
        if(Ext.isGecko || Ext.isOpera) {
            document.addEventListener("DOMContentLoaded", fireDocReady, false);
        }//对于IE，通过强行在document加入一个元素，判断这个元素是否加载完来判断文档是否加载完
        //如果加载完了该元素的onreadystatechange的回调函数中的readyState == "complete"
        else if(Ext.isIE){
            document.write("<s"+'cript id="ie-deferred-loader" defer="defer" src="/'+'/:"></s'+"cript>");
            var defer = document.getElementById("ie-deferred-loader");
            defer.onreadystatechange = function(){
                if(this.readyState == "complete"){
                    fireDocReady();
                }
            };
        }
        //对于Safari，每隔10ms监听它的document.readyState是否==="complete"
        else if(Ext.isSafari){
            docReadyProcId = setInterval(function(){
                var rs = document.readyState;
                if(rs == "complete") {
                    fireDocReady();
                 }
            }, 10);
        }
        //觉得这里没有必要采用Ext.lib.event.
        // no matter what, make sure it fires on load
        E.on(window, "load", fireDocReady);
    };
   
    //隔多长时间执行一次h函数。
    var createBuffered = function(h, o){
        var task = new Ext.util.DelayedTask(h);
        return function(e){
            // create new event object impl so new events don't wipe out properties
            e = new Ext.EventObjectImpl(e);
            task.delay(o.buffer, h, null, [e]);
        };
    };

    //一个监听执行一次就被remove
    var createSingle = function(h, el, ename, fn){
        return function(e){
            Ext.EventManager.removeListener(el, ename, fn);
            h(e);
        };
    };

    //多长时间之后执行h函数
    var createDelayed = function(h, o){
        return function(e){
            // create new event object impl so new events don't wipe out properties
            e = new Ext.EventObjectImpl(e);
            setTimeout(function(){
                h(e);
            }, o.delay || 10);
        };
    };
    
    //为element的ename事件添加fn的监听函数。
    var listen = function(element, ename, opt, fn, scope){
        var o = (!opt || typeof opt == "boolean") ? {} : opt;
        fn = fn || o.fn; scope = scope || o.scope;
        var el = Ext.getDom(element);
        if(!el){
            throw "Error listening for \"" + ename + '\". Element "' + element + '" doesn\'t exist.';
        }
        //对传进来的fn进行包装
        var h = function(e){
            e = Ext.EventObject.setEvent(e);
            var t;
            //找到事件的元素或附近的元素，o.delegate是select
            if(o.delegate){
                t = e.getTarget(o.delegate, el);
                if(!t){
                    return;
                }
            }else{
                t = e.target;
            }
            //对元素事件的三种操作，一：stop,二、preventDefault，三、stopPropagation
            if(o.stopEvent === true){
                e.stopEvent();
            }
            if(o.preventDefault === true){
               e.preventDefault();
            }
            if(o.stopPropagation === true){
                e.stopPropagation();
            }
             //是否采用原始的浏览事件e,而不是进行了包装的事件。
            if(o.normalized === false){
                e = e.browserEvent;
            }
             //fn(event,this,options)
            fn.call(scope || el, e, t, o);
        };
        
        //推迟执行
        if(o.delay){
            h = createDelayed(h, o);
        }
        //监听只执行一次
        if(o.single){
            h = createSingle(h, el, ename, fn);
        }
        //隔多少时间就执行一次
        if(o.buffer){
            h = createBuffered(h, o);
        }
        fn._handlers = fn._handlers || [];
        fn._handlers.push([Ext.id(el), ename, h]);
        
        //为el的ename事件注册h函数。
        E.on(el, ename, h);
        
        if(ename == "mousewheel" && el.addEventListener){ // workaround for jQuery
            el.addEventListener("DOMMouseScroll", h, false);
            E.on(window, 'unload', function(){
                el.removeEventListener("DOMMouseScroll", h, false);
            });
        }
        //对document的mousedown,在stopEvent等中要先fire,之后才stop.
        if(ename == "mousedown" && el == document){ // fix stopped mousedowns on the document
            Ext.EventManager.stoppedMouseDownEvent.addListener(h);
        }
        return h;
    };

    var stopListening = function(el, ename, fn){
        var id = Ext.id(el), hds = fn._handlers, hd = fn;
        if(hds){
            for(var i = 0, len = hds.length; i < len; i++){
                var h = hds[i];
                if(h[0] == id && h[1] == ename){
                    hd = h[2];
                    hds.splice(i, 1);
                    break;
                }
            }
        }
        E.un(el, ename, hd);
        el = Ext.getDom(el);
        if(ename == "mousewheel" && el.addEventListener){
            el.removeEventListener("DOMMouseScroll", hd, false);
        }
        if(ename == "mousedown" && el == document){ // fix stopped mousedowns on the document
            Ext.EventManager.stoppedMouseDownEvent.removeListener(hd);
        }
    };

    var propRe = /^(?:scope|delay|buffer|single|stopEvent|preventDefault|stopPropagation|normalized|args|delegate)$/;
    var pub = {

    /**
     * Appends an event handler to an element.  The shorthand version {@link #on} is equivalent.  Typically you will
     * use {@link Ext.Element#addListener} directly on an Element in favor of calling this version.
     * @param {String/HTMLElement} el The html element or id to assign the event handler to
     * @param {String} eventName The type of event to listen for
     * @param {Function} handler The handler function the event invokes
     * @param {Object} scope (optional) The scope in which to execute the handler
     * function (the handler function's "this" context)
     * @param {Object} options (optional) An object containing handler configuration properties.
     * This may contain any of the following properties:<ul>
     * <li>scope {Object} : The scope in which to execute the handler function. The handler function's "this" context.</li>
     * <li>delegate {String} : A simple selector to filter the target or look for a descendant of the target</li>
     * <li>stopEvent {Boolean} : True to stop the event. That is stop propagation, and prevent the default action.</li>
     * <li>preventDefault {Boolean} : True to prevent the default action</li>
     * <li>stopPropagation {Boolean} : True to prevent event propagation</li>
     * <li>normalized {Boolean} : False to pass a browser event to the handler function instead of an Ext.EventObject</li>
     * <li>delay {Number} : The number of milliseconds to delay the invocation of the handler after te event fires.</li>
     * <li>single {Boolean} : True to add a handler to handle just the next firing of the event, and then remove itself.</li>
     * <li>buffer {Number} : Causes the handler to be scheduled to run in an {@link Ext.util.DelayedTask} delayed
     * by the specified number of milliseconds. If the event fires again within that time, the original
     * handler is <em>not</em> invoked, but the new handler is scheduled in its place.</li>
     * </ul><br>
     * <p>See {@link Ext.Element#addListener} for examples of how to use these options.</p>
     */
    	//支持和observable中addListener一样的传参的形式
    	//这个函数和observable中addListener的结构差不多。不同的把具体的处理放到listen中。
        addListener : function(element, eventName, fn, scope, options){
            if(typeof eventName == "object"){
                var o = eventName;
                for(var e in o){
                    if(propRe.test(e)){
                        continue;
                    }
                    if(typeof o[e] == "function"){
                        // shared options
                        listen(element, e, o, o[e], o.scope);
                    }else{
                        // individual options
                        listen(element, e, o[e]);
                    }
                }
                return;
            }
            return listen(element, eventName, options, fn, scope);
        },

        /**
         * Removes an event handler from an element.  The shorthand version {@link #un} is equivalent.  Typically
         * you will use {@link Ext.Element#removeListener} directly on an Element in favor of calling this version.
         * @param {String/HTMLElement} el The id or html element from which to remove the event
         * @param {String} eventName The type of event
         * @param {Function} fn The handler function to remove
         * @return {Boolean} True if a listener was actually removed, else false
         */
        removeListener : function(element, eventName, fn){
            return stopListening(element, eventName, fn);
        },

        /**
         * Fires when the document is ready (before onload and before images are loaded). Can be
         * accessed shorthanded as Ext.onReady().
         * @param {Function} fn The method the event invokes
         * @param {Object} scope (optional) An object that becomes the scope of the handler
         * @param {boolean} options (optional) An object containing standard {@link #addListener} options
         */
        onDocumentReady : function(fn, scope, options){
           //document已经load,为docReadyEvent 进行addListener、fire(),clearListeners();
        	if(docReadyState){ // if it already fired
                docReadyEvent.addListener(fn, scope, options);
                docReadyEvent.fire();
                docReadyEvent.clearListeners();
                return;
            }
            //初始化Document Ready.
            if(!docReadyEvent){
                initDocReady();
            }
            //初始化之后再addListener
            docReadyEvent.addListener(fn, scope, options);
        },

        /**
         * Fires when the window is resized and provides resize event buffering (50 milliseconds), passes new viewport width and height to handlers.
         * @param {Function} fn        The method the event invokes
         * @param {Object}   scope    An object that becomes the scope of the handler
         * @param {boolean}  options
         */
        onWindowResize : function(fn, scope, options){
            if(!resizeEvent){
                resizeEvent = new Ext.util.Event();
                resizeTask = new Ext.util.DelayedTask(function(){
                    resizeEvent.fire(D.getViewWidth(), D.getViewHeight());
                });
                E.on(window, "resize", this.fireWindowResize, this);
            }
            resizeEvent.addListener(fn, scope, options);
        },

        // exposed only to allow manual firing
        fireWindowResize : function(){
            if(resizeEvent){
                if((Ext.isIE||Ext.isAir) && resizeTask){
                    resizeTask.delay(50);
                }else{
                    resizeEvent.fire(D.getViewWidth(), D.getViewHeight());
                }
            }
        },

        /**
         * Fires when the user changes the active text size. Handler gets called with 2 params, the old size and the new size.
         * @param {Function} fn        The method the event invokes
         * @param {Object}   scope    An object that becomes the scope of the handler
         * @param {boolean}  options
         */
        onTextResize : function(fn, scope, options){
            if(!textEvent){
                textEvent = new Ext.util.Event();
                var textEl = new Ext.Element(document.createElement('div'));
                textEl.dom.className = 'x-text-resize';
                textEl.dom.innerHTML = 'X';
                textEl.appendTo(document.body);
                textSize = textEl.dom.offsetHeight;
                setInterval(function(){
                    if(textEl.dom.offsetHeight != textSize){
                        textEvent.fire(textSize, textSize = textEl.dom.offsetHeight);
                    }
                }, this.textResizeInterval);
            }
            textEvent.addListener(fn, scope, options);
        },

        /**
         * Removes the passed window resize listener.
         * @param {Function} fn        The method the event invokes
         * @param {Object}   scope    The scope of handler
         */
        removeResizeListener : function(fn, scope){
            if(resizeEvent){
                resizeEvent.removeListener(fn, scope);
            }
        },

        // private
        fireResize : function(){
            if(resizeEvent){
                resizeEvent.fire(D.getViewWidth(), D.getViewHeight());
            }
        },
        /**
         * Url used for onDocumentReady with using SSL (defaults to Ext.SSL_SECURE_URL)
         */
        ieDeferSrc : false,
        /**
         * The frequency, in milliseconds, to check for text resize events (defaults to 50)
         */
        textResizeInterval : 50
    };
     /**
     * Appends an event handler to an element.  Shorthand for {@link #addListener}.
     * @param {String/HTMLElement} el The html element or id to assign the event handler to
     * @param {String} eventName The type of event to listen for
     * @param {Function} handler The handler function the event invokes
     * @param {Object} scope (optional) The scope in which to execute the handler
     * function (the handler function's "this" context)
     * @param {Object} options (optional) An object containing standard {@link #addListener} options
     * @member Ext.EventManager
     * @method on
     */
    pub.on = pub.addListener;
    /**
     * Removes an event handler from an element.  Shorthand for {@link #removeListener}.
     * @param {String/HTMLElement} el The id or html element from which to remove the event
     * @param {String} eventName The type of event
     * @param {Function} fn The handler function to remove
     * @return {Boolean} True if a listener was actually removed, else false
     * @member Ext.EventManager
     * @method un
     */
    pub.un = pub.removeListener;

    pub.stoppedMouseDownEvent = new Ext.util.Event();
    return pub;
}();
/**
  * Fires when the document is ready (before onload and before images are loaded).  Shorthand of {@link Ext.EventManager#onDocumentReady}.
  * @param {Function} fn        The method the event invokes
  * @param {Object}   scope    An  object that becomes the scope of the handler
  * @param {boolean}  override If true, the obj passed in becomes
  *                             the execution scope of the listener
  * @member Ext
  * @method onReady
 */
Ext.onReady = Ext.EventManager.onDocumentReady;

Ext.onReady(function(){
    var bd = Ext.getBody();
    if(!bd){ return; }

    var cls = [
            Ext.isIE ? "ext-ie " + (Ext.isIE6 ? 'ext-ie6' : 'ext-ie7')
            : Ext.isGecko ? "ext-gecko"
            : Ext.isOpera ? "ext-opera"
            : Ext.isSafari ? "ext-safari" : ""];

    if(Ext.isMac){
        cls.push("ext-mac");
    }
    if(Ext.isLinux){
        cls.push("ext-linux");
    }
    if(Ext.isBorderBox){
        cls.push('ext-border-box');
    }
    if(Ext.isStrict){ // add to the parent to allow for selectors like ".ext-strict .ext-ie"
        var p = bd.dom.parentNode;
        if(p){
            p.className += ' ext-strict';
        }
    }
    bd.addClass(cls.join(' '));
});

/**
 * @class Ext.EventObject
 * EventObject exposes the Yahoo! UI Event functionality directly on the object
 * passed to your event handler. It exists mostly for convenience. It also fixes the annoying null checks automatically to cleanup your code
 * Example:
 * <pre><code>
 function handleClick(e){ // e is not a standard event object, it is a Ext.EventObject
    e.preventDefault();
    var target = e.getTarget();
    ...
 }
 var myDiv = Ext.get("myDiv");
 myDiv.on("click", handleClick);
 //or
 Ext.EventManager.on("myDiv", 'click', handleClick);
 Ext.EventManager.addListener("myDiv", 'click', handleClick);
 </code></pre>
 * @singleton
 */
Ext.EventObject = function(){

    var E = Ext.lib.Event;

    // safari keypress events for special keys return bad keycodes
    var safariKeys = {
        63234 : 37, // left
        63235 : 39, // right
        63232 : 38, // up
        63233 : 40, // down
        63276 : 33, // page up
        63277 : 34, // page down
        63272 : 46, // delete
        63273 : 36, // home
        63275 : 35  // end
    };

    // normalize button clicks
    //表示鼠标的左，中，右键，每种浏览器不一同，统一为0,1,2.
    var btnMap = Ext.isIE ? {1:0,4:1,2:2} :
                (Ext.isSafari ? {1:0,2:1,3:2} : {0:0,1:1,2:2});

    Ext.EventObjectImpl = function(e){
        if(e){
            this.setEvent(e.browserEvent || e);
        }
    };
    Ext.EventObjectImpl.prototype = {
        /** The normal browser event */
        browserEvent : null,
        /** The button pressed in a mouse event */
        button : -1,
        /** True if the shift key was down during the event */
        shiftKey : false,
        /** True if the control key was down during the event */
        ctrlKey : false,
        /** True if the alt key was down during the event */
        altKey : false,
         
        //一些常用的按键。
        /** Key constant @type Number */
        BACKSPACE : 8,
        /** Key constant @type Number */
        TAB : 9,
        /** Key constant @type Number */
        RETURN : 13,
        /** Key constant @type Number */
        ENTER : 13,
        /** Key constant @type Number */
        SHIFT : 16,
        /** Key constant @type Number */
        CONTROL : 17,
        /** Key constant @type Number */
        ESC : 27,
        /** Key constant @type Number */
        SPACE : 32,
        /** Key constant @type Number */
        PAGEUP : 33,
        /** Key constant @type Number */
        PAGEDOWN : 34,
        /** Key constant @type Number */
        END : 35,
        /** Key constant @type Number */
        HOME : 36,
        /** Key constant @type Number */
        LEFT : 37,
        /** Key constant @type Number */
        UP : 38,
        /** Key constant @type Number */
        RIGHT : 39,
        /** Key constant @type Number */
        DOWN : 40,
        /** Key constant @type Number */
        DELETE : 46,
        /** Key constant @type Number */
        F5 : 116,

           /** @private */
        //包装事件。
        setEvent : function(e){
            if(e == this || (e && e.browserEvent)){ // already wrapped
                return e;
            }
            //设定 this.browserEvent=传入的浏览器的event,做为是否包装的标识。
            this.browserEvent = e;
            if(e){
                // normalize buttons，比prototype实现简单多了。表示鼠标按键。
                this.button = e.button ? btnMap[e.button] : (e.which ? e.which-1 : -1);
                if(e.type == 'click' && this.button == -1){
                    this.button = 0;
                }
                //事件名
                this.type = e.type;
                
                //三个功能组合键
                this.shiftKey = e.shiftKey;
                // mac metaKey behaves like ctrlKey
                this.ctrlKey = e.ctrlKey || e.metaKey;
                this.altKey = e.altKey;
               
                //键盘事件的keywode,and charcode
                // in getKey these will be normalized for the mac
                this.keyCode = e.keyCode;
                this.charCode = e.charCode;
                
                //我倒是觉得这里的不好，不应该采用 Ext.lib.Event，组合在一起很方便啊
                //可能是出于版本兼容等问题的考虑吧。
                // cache the target for the delayed and or buffered events
                this.target = E.getTarget(e);
                // same for XY
                this.xy = E.getXY(e);
            }else{
                this.button = -1;
                this.shiftKey = false;
                this.ctrlKey = false;
                this.altKey = false;
                this.keyCode = 0;
                this.charCode =0;
                this.target = null;
                this.xy = [0, 0];
            }
            return this;
        },

        /**
         * Stop the event (preventDefault and stopPropagation)
         */
        //觉得stopEvent，preventDefault,stopPropagation完全可以独立实现。
        stopEvent : function(){
            if(this.browserEvent){
                if(this.browserEvent.type == 'mousedown'){
                    Ext.EventManager.stoppedMouseDownEvent.fire(this);
                }
                E.stopEvent(this.browserEvent);
            }
        },

        /**
         * Prevents the browsers default handling of the event.
         */
        // this.browserEven.returnValue = false;        
        preventDefault : function(){
            if(this.browserEvent){
                E.preventDefault(this.browserEvent);
            }
        },

        /** @private */
        //判断键是不是字符按键，除去了一些功能键
        isNavKeyPress : function(){
            var k = this.keyCode;
            k = Ext.isSafari ? (safariKeys[k] || k) : k;
            return (k >= 33 && k <= 40) || k == this.RETURN || k == this.TAB || k == this.ESC;
        },
        
        //判断是不是特殊键。
        isSpecialKey : function(){
            var k = this.keyCode;
            return (this.type == 'keypress' && this.ctrlKey) || k == 9 || k == 13  || k == 40 || k == 27 ||
            (k == 16) || (k == 17) ||
            (k >= 18 && k <= 20) ||
            (k >= 33 && k <= 35) ||
            (k >= 36 && k <= 39) ||
            (k >= 44 && k <= 45);
        },
        /**
         * Cancels bubbling of the event.
         */
        //this.browserEvent.cancelBubble=false
        stopPropagation : function(){
            if(this.browserEvent){
                if(this.browserEvent.type == 'mousedown'){
                    Ext.EventManager.stoppedMouseDownEvent.fire(this);
                }
                E.stopPropagation(this.browserEvent);
            }
        },
        
       //取得键值和其代码
        /**
         * Gets the key code for the event.
         * @return {Number}
         */
        getCharCode : function(){
            return this.charCode || this.keyCode;
        },

        /**
         * Returns a normalized keyCode for the event.
         * @return {Number} The key code
         */
        getKey : function(){
            var k = this.keyCode || this.charCode;
            return Ext.isSafari ? (safariKeys[k] || k) : k;
        },
        
        //取得事件页面的位置
        /**
         * Gets the x coordinate of the event.
         * @return {Number}
         */
        getPageX : function(){
            return this.xy[0];
        },

        /**
         * Gets the y coordinate of the event.
         * @return {Number}
         */
        getPageY : function(){
            return this.xy[1];
        },

        /**
         * Gets the time of the event.
         * @return {Number}
         */
        getTime : function(){
            if(this.browserEvent){
                return E.getTime(this.browserEvent);
            }
            return null;
        },

        /**
         * Gets the page coordinates of the event.
         * @return {Array} The xy values like [x, y]
         */
        getXY : function(){
            return this.xy;
        },

        /**
         * Gets the target for the event.
         * @param {String} selector (optional) A simple selector to filter the target or look for an ancestor of the target
         * @param {Number/Mixed} maxDepth (optional) The max depth to
                search as a number or element (defaults to 10 || document.body)
         * @param {Boolean} returnEl (optional) True to return a Ext.Element object instead of DOM node
         * @return {HTMLelement}
         */
        //和prototype中findElement差不多，找到事件源元素附近的元素。
        getTarget : function(selector, maxDepth, returnEl){
        	var t = Ext.get(this.target);
            return selector ? t.findParent(selector, maxDepth, returnEl) : (returnEl ? t : this.target);
        },
        
        /**
         * Gets the related target.
         * @return {HTMLElement}
         */
        getRelatedTarget : function(){
            if(this.browserEvent){
                return E.getRelatedTarget(this.browserEvent);
            }
            return null;
        },

        /**
         * Normalizes mouse wheel delta across browsers
         * @return {Number} The delta
         */
        getWheelDelta : function(){
            var e = this.browserEvent;
            var delta = 0;
            if(e.wheelDelta){ /* IE/Opera. */
                delta = e.wheelDelta/120;
            }else if(e.detail){ /* Mozilla case. */
                delta = -e.detail/3;
            }
            return delta;
        },

        /**
         * Returns true if the control, meta, shift or alt key was pressed during this event.
         * @return {Boolean}
         */
        hasModifier : function(){
            return ((this.ctrlKey || this.altKey) || this.shiftKey) ? true : false;
        },

        /**
         * Returns true if the target of this event equals el or is a child of el
         * @param {Mixed} el
         * @param {Boolean} related (optional) true to test if the related target is within el instead of the target
         * @return {Boolean}
         */
        within : function(el, related){
            var t = this[related ? "getRelatedTarget" : "getTarget"]();
            return t && Ext.fly(el).contains(t);
        },

        getPoint : function(){
            return new Ext.lib.Point(this.xy[0], this.xy[1]);
        }
    };

    return new Ext.EventObjectImpl();
}();