/*
对原生event的包装
首先将其Native化
*/
var Event = new Native({
//族名,为$type提供精准类型判断
name: 'Event',
initialize: function(event, win){
  win = win || window;
  var doc = win.document;
  event = event || win.event;
 
  //根据私有属性判断是否已包装
  if (event.$extended) return event;
  this.$extended = true;
  var type = event.type;
  //针对不同浏览器获取的事件源对象
  var target = event.target || event.srcElement;
  //nodeType为3时为空白节点，显然不是我们需要的，所以向上获取
  while (target && target.nodeType == 3) target = target.parentNode;
 
  if (type.test(/key/)){
  //针对不同浏览器获取的键值
  var code = event.which || event.keyCode;
  var key = Event.Keys.keyOf(code);
  if (type == 'keydown'){
    //经测试，这段兼容处理貌似还存在bug，希望后续版本会修正
    var fKey = code - 111;
    if (fKey > 0 && fKey < 13) key = 'f' + fKey;
  }
  key = key || String.fromCharCode(code).toLowerCase();
  } else if (type.match(/(click|mouse|menu)/i)){
  //根据DTD的不同模式使doc指向不同节点
  doc = (!doc.compatMode || doc.compatMode == 'CSS1Compat') ? doc.html : doc.body;
  var page = {
    x: event.pageX || event.clientX + doc.scrollLeft,
    y: event.pageY || event.clientY + doc.scrollTop
  };
  var client = {
    x: (event.pageX) ? event.pageX - win.pageXOffset : event.clientX,
    y: (event.pageY) ? event.pageY - win.pageYOffset : event.clientY
  };
  //滚轮支持
  if (type.match(/DOMMouseScroll|mousewheel/)){
    var wheel = (event.wheelDelta) ? event.wheelDelta / 120 : -(event.detail || 0) / 3;
  }
  //右键判断
  var rightClick = (event.which == 3) || (event.button == 2);
  //事件相关对象
  var related = null;
  if (type.match(/over|out/)){
    switch (type){
    case 'mouseover': related = event.relatedTarget || event.fromElement; break;
    case 'mouseout': related = event.relatedTarget || event.toElement;
    }
    if (!(function(){
    while (related && related.nodeType == 3) related = related.parentNode;
    return true;
    }).create({attempt: Browser.Engine.gecko})()) related = false;
  }
  }
  return $extend(this, {
  event: event,
  type: type,
 
  page: page,
  client: client,
  rightClick: rightClick,
 
  wheel: wheel,
 
  relatedTarget: related,
  target: target,
 
  code: code,
  key: key,
 
  shift: event.shiftKey,
  control: event.ctrlKey,
  alt: event.altKey,
  meta: event.metaKey
  });
}
});
//键盘代码的可读表示
Event.Keys = new Hash({
'enter': 13,
'up': 38,
'down': 40,
'left': 37,
'right': 39,
'esc': 27,
'space': 32,
'backspace': 8,
'tab': 9,
'delete': 46
});
//对Event的扩展实现
Event.implement({
//阻止事件冒泡和事件返回
stop: function(){
  return this.stopPropagation().preventDefault();
},
//阻止事件冒泡
stopPropagation: function(){
  if (this.event.stopPropagation) this.event.stopPropagation();
  else this.event.cancelBubble = true;
  return this;
},
//阻止事件返回
preventDefault: function(){
  if (this.event.preventDefault) this.event.preventDefault();
  else this.event.returnValue = false;
  return this;
}
});