javascript 图片滚动兑现（二）之代码实现

var common = {
	$ : function(objName) {
		if (document.getElementById) {
			return eval('document.getElementById("' + objName + '")')
		} else {
			return eval('document.all.' + objName)
		}
	},
	isIE : navigator.appVersion.indexOf("MSIE") != -1 ? true : false,
	addEvent : function(l, i, I) {
		if (l.attachEvent) {
			l.attachEvent("on" + i, I)
		} else {
			l.addEventListener(i, I, false)
		}
	},
	delEvent : function(l, i, I) {
		if (l.detachEvent) {
			l.detachEvent("on" + i, I)
		} else {
			l.removeEventListener(i, I, false)
		}
	},
	readCookie : function(O) {
		var o = "", l = O + "=";
		if (document.cookie.length > 0) {
			var i = document.cookie.indexOf(l);
			if (i != -1) {
				i += l.length;
				var I = document.cookie.indexOf(";", i);
				if (I == -1)
					I = document.cookie.length;
				o = unescape(document.cookie.substring(i, I))
			}
		};
		return o
	},
	writeCookie : function(i, l, o, c) {
		var O = "", I = "";
		if (o != null) {
			O = new Date((new Date).getTime() + o * 3600000);
			O = "; expires=" + O.toGMTString()
		};
		if (c != null) {
			I = ";domain=" + c
		};
		document.cookie = i + "=" + escape(l) + O + I
	},
	readStyle : function(I, l) {
		if (I.style[l]) {
			return I.style[l]
		} else if (I.currentStyle) {
			return I.currentStyle[l]
		} else if (document.defaultView && document.defaultView.getComputedStyle) {
			var i = document.defaultView.getComputedStyle(I, null);
			return i.getPropertyValue(l)
		} else {
			return null
		}
	}
};

function ScrollPic(scrollContId, arrLeftId, arrRightId, dotListId) {
	this.scrollContId = scrollContId;//滚动区域id
	this.arrLeftId = arrLeftId;//向左滚动按钮
	this.arrRightId = arrRightId;//向右滚动按钮
	this.dotListId = dotListId;//
	this.dotClassName = "dotItem";
	this.dotOnClassName = "dotItemOn";
	this.dotObjArr = [];//滚动对象数组
	this.pageWidth = 0;//滚动区域宽度
	this.frameWidth = 0;//
	this.speed = 10;//默认滚动速度
	this.space = 10;
	this.pageIndex = 0;//默认第一页
	this.autoPlay = true;//是否自动播放
	this.autoPlayTime = 5;//自动播放时间间隔
	var _autoTimeObj, _scrollTimeObj, _state = "ready";//，定时标志，动画是否可以开始
	this.stripDiv = document.createElement("DIV");
	this.listDiv01 = document.createElement("DIV");
	this.listDiv02 = document.createElement("DIV");
	if (!ScrollPic.childs) {
		ScrollPic.childs = []
	};
	this.ID = ScrollPic.childs.length;//滚动条目的长度
	ScrollPic.childs.push(this);
	/**
	 *初始化函数 
	 */
	this.initialize = function() {
		if (!this.scrollContId) {
			throw new Error("scrollContId.");
			return
		};
		this.scrollContDiv = common.$(this.scrollContId);//拿到滚动区域
		if (!this.scrollContDiv) {
			throw new Error("scrollContId.(scrollContId = \"" + this.scrollContId + "\")");
			return
		};
		this.scrollContDiv.style.width = this.frameWidth + "px";//设置滚动区域宽度
		this.scrollContDiv.style.overflow = "hidden";//超出区域隐藏
		this.listDiv01.innerHTML = this.listDiv02.innerHTML = this.scrollContDiv.innerHTML;//将滚动条目复制两份
		this.scrollContDiv.innerHTML = "";//清空原始区域
		this.scrollContDiv.appendChild(this.stripDiv);
		this.stripDiv.appendChild(this.listDiv01);
		this.stripDiv.appendChild(this.listDiv02);
		this.stripDiv.style.overflow = "hidden";//设置clone后的div样式
		this.stripDiv.style.zoom = "1";//网页为原始大小
		this.stripDiv.style.width = "32766px";
		this.listDiv01.style.cssFloat = "left";//所有元素向左浮动
		this.listDiv02.style.cssFloat = "left";
		common.addEvent(this.scrollContDiv, "mouseover", Function("ScrollPic.childs[" + this.ID + "].stop()"));//鼠标经过的话停止动画
		common.addEvent(this.scrollContDiv, "mouseout", Function("ScrollPic.childs[" + this.ID + "].play()"));//鼠标离开的话开始动画
		if (this.arrLeftId) {
			this.arrLeftObj = common.$(this.arrLeftId);//向左箭头
			if (this.arrLeftObj) {
				/**
				 *注册向左的动画事件 
				 */
				common.addEvent(this.arrLeftObj, "mousedown", Function("ScrollPic.childs[" + this.ID + "].rightMouseDown()"));
				common.addEvent(this.arrLeftObj, "mouseup", Function("ScrollPic.childs[" + this.ID + "].rightEnd()"));
				common.addEvent(this.arrLeftObj, "mouseout", Function("ScrollPic.childs[" + this.ID + "].rightEnd()"))
			}
		};
		if (this.arrRightId) {
			this.arrRightObj = common.$(this.arrRightId);
			if (this.arrRightObj) {
				/**
				 *注册向右的动画事件 
				 */
				common.addEvent(this.arrRightObj, "mousedown", Function("ScrollPic.childs[" + this.ID + "].leftMouseDown()"));
				common.addEvent(this.arrRightObj, "mouseup", Function("ScrollPic.childs[" + this.ID + "].leftEnd()"));
				common.addEvent(this.arrRightObj, "mouseout", Function("ScrollPic.childs[" + this.ID + "].leftEnd()"))
			}
		};
		/**
		 * 分页处理
		 */
		if (this.dotListId) {
			this.dotListObj = common.$(this.dotListId);
			if (this.dotListObj) {
				var pages = Math.round(this.listDiv01.offsetWidth / this.frameWidth + 0.4), i, tempObj;//分页参数
				for ( i = 0; i < pages; i++) {
					tempObj = document.createElement("span");
					this.dotListObj.appendChild(tempObj);
					this.dotObjArr.push(tempObj);
					if (i == this.pageIndex) {
						tempObj.className = this.dotClassName
					} else {
						tempObj.className = this.dotOnClassName
					};
					tempObj.title = "" + (i + 1) + "";
					common.addEvent(tempObj, "click", Function("ScrollPic.childs[" + this.ID + "].pageTo(" + i + ")"))
				}
			}
		};
		/**
		 *如果是自动滚动的话直接触发play()事件
		 */
		if (this.autoPlay) {
			this.play()
		}
	};
	/**
	 *向左滚动事件 
	 */
	this.leftMouseDown = function() {
		if (_state != "ready") {
			return//如果动画内容没有准备好则return
		};
		_state = "floating";//滚动中
		_scrollTimeObj = setInterval("ScrollPic.childs[" + this.ID + "].moveLeft()", this.speed)
	};
	/**
	 *向右滚动事件 
	 */
	this.rightMouseDown = function() {
		if (_state != "ready") {
			return
		};
		_state = "floating";
		_scrollTimeObj = setInterval("ScrollPic.childs[" + this.ID + "].moveRight()", this.speed)
	};
	/**
	 *向左具体滚动逻辑 
	 */
	this.moveLeft = function() {
		//如果原始div滚动后隐藏在滚动条左侧的宽度+滚动的像素>=克隆后div的滚动宽度，则重新开始从头滚动，否则以space个滚动单位继续滚动
		if (this.scrollContDiv.scrollLeft + this.space >= this.listDiv01.scrollWidth) {
			this.scrollContDiv.scrollLeft = this.scrollContDiv.scrollLeft + this.space - this.listDiv01.scrollWidth
		} else {
			this.scrollContDiv.scrollLeft += this.space
		};
		this.accountPageIndex()//滚动后重新计算当且页值
	};
	/**
	 *向右具体滚动逻辑（同上） 
	 */
	this.moveRight = function() {
		if (this.scrollContDiv.scrollLeft - this.space <= 0) {
			this.scrollContDiv.scrollLeft = this.listDiv01.scrollWidth + this.scrollContDiv.scrollLeft - this.space
		} else {
			this.scrollContDiv.scrollLeft -= this.space
		};
		this.accountPageIndex()
	};
	/**
	 *如果向左滚动到结尾时 
	 */
	this.leftEnd = function() {
		if (_state != "floating") {
			return
		};
		_state = "stoping";
		clearInterval(_scrollTimeObj);
		var fill = this.pageWidth - this.scrollContDiv.scrollLeft % this.pageWidth;
		this.move(fill)
	};
	/**
	 *如果向右滚动到结尾时 
	 */
	this.rightEnd = function() {
		if (_state != "floating") {
			return//如果不在动画中
		};
		_state = "stoping";//设置动画为停止状态
		clearInterval(_scrollTimeObj);//清空定时标志
		var fill = -this.scrollContDiv.scrollLeft % this.pageWidth;
		this.move(fill)
	};
	/**
	 * 具体动画逻辑都在此
	 */
	this.move = function(num, quick) {
		var thisMove = num / 5;//移动单位
		if (!quick) {
			/**
			 *移动单位不能超过每次移动像素 
			 */
			if (thisMove > this.space) {
				thisMove = this.space
			};
			if (thisMove < -this.space) {
				thisMove = -this.space
			}
		};
		if (Math.abs(thisMove) < 1 && thisMove != 0) {
			thisMove = thisMove >= 0 ? 1 : -1
		} else {
			thisMove = Math.round(thisMove)
		};
		var temp = this.scrollContDiv.scrollLeft + thisMove;
		/**
		 *滚动逻辑同上，只是滚动单位变为 thisMove
		 */
		if (thisMove > 0) {
			if (this.scrollContDiv.scrollLeft + thisMove >= this.listDiv01.scrollWidth) {
				this.scrollContDiv.scrollLeft = this.scrollContDiv.scrollLeft + thisMove - this.listDiv01.scrollWidth
			} else {
				this.scrollContDiv.scrollLeft += thisMove
			}
		} else {
			if (this.scrollContDiv.scrollLeft - thisMove <= 0) {
				this.scrollContDiv.scrollLeft = this.listDiv01.scrollWidth + this.scrollContDiv.scrollLeft - thisMove
			} else {
				this.scrollContDiv.scrollLeft += thisMove
			}
		};
		num -= thisMove;
		if (Math.abs(num) == 0) {
			_state = "ready";
			if (this.autoPlay) {
				this.play()
			};
			this.accountPageIndex();//重新计算页码
			return
		} else {
			this.accountPageIndex();//先计算页码
			setTimeout("ScrollPic.childs[" + this.ID + "].move(" + num + "," + quick + ")", this.speed)//递归调用直到无法移动
		}
	};
	/**
	 *下一个 
	 */
	this.next = function() {
		if (_state != "ready") {
			return
		};
		_state = "stoping";
		this.move(this.pageWidth, true)
	};
	/**
	 * 触发动画的方法
	 */
	this.play = function() {
		if (!this.autoPlay) {
			return
		};
		clearInterval(_autoTimeObj);//先清除定时标志（以免冲突）
		_autoTimeObj = setInterval("ScrollPic.childs[" + this.ID + "].next()", this.autoPlayTime * 1000)//定时动画
	};
	/**
	 *清除定时标志，停止动画 
	 */
	this.stop = function() {
		clearInterval(_autoTimeObj)
	};
	/**
	 *直接跳到第几页 
	 */
	this.pageTo = function(num) {
		if (_state != "ready") {
			return
		};
		_state = "stoping";
		var fill = num * this.frameWidth - this.scrollContDiv.scrollLeft;
		this.move(fill, true)
	};
	/**
	 *计算动画参数 
	 */
	this.accountPageIndex = function() {
		this.pageIndex = Math.round(this.scrollContDiv.scrollLeft / this.frameWidth);
		if (this.pageIndex > Math.round(this.listDiv01.offsetWidth / this.frameWidth + 0.4) - 1) {
			this.pageIndex = 0
		};
		var i;
		for ( i = 0; i < this.dotObjArr.length; i++) {
			if (i == this.pageIndex) {
				this.dotObjArr[i].className = this.dotClassName
			} else {
				this.dotObjArr[i].className = this.dotOnClassName
			}
		}
	}
};