var imgGetID = function (id) {
	return "string" == typeof id ? document.getElementById(id) : id;
}

var Class = {
	create: function() {
		return function() {
		   this.initialize.apply(this, arguments);
		}
	}
}
Object.extend = function(destination, source) {
	for (var property in source) {
	   destination[property] = source[property];
	}
	return destination;
}
var TransformView = Class.create();

TransformView.prototype = {
	//容器对象,滑动对象,切换参数,切换数量
	initialize: function(container, slider, parameter, count, options) {
		if(parameter <= 0 || count <= 0) return;
		var oContainer = imgGetID(container), oSlider = imgGetID(slider), oThis = this;this.Index = 0;//当前索引
		
		this._timer = null;//定时器
		this._slider = oSlider;//滑动对象
		this._parameter = parameter;//切换参数
		this._count = count || 0;//切换数量
		this._target = 0;//目标参数
		
		this.SetOptions(options);
		
		this.Up = !!this.options.Up;
		this.Step = Math.abs(this.options.Step);
		this.Time = Math.abs(this.options.Time);
		this.Auto = !!this.options.Auto;
		this.Pause = Math.abs(this.options.Pause);
		this.onStart = this.options.onStart;
		this.onFinish = this.options.onFinish;
		
		oContainer.style.overflow = "hidden";
		oContainer.style.position = "relative";
		
		oSlider.style.position = "absolute";
		oSlider.style.top = oSlider.style.left = 0;
	},
	//设置默认属性
	SetOptions: function(options) {
		this.options = {//默认值
		   Up:    true,//是否向上(否则向左)
		   Step:   5,//滑动变化率
		   Time:   10,//滑动延时
		   Auto:   true,//是否自动转换
		   Pause:   2000,//停顿时间(Auto为true时有效)
		   onStart: function(){},//开始转换时执行
		   onFinish: function(){}//完成转换时执行
		};
		Object.extend(this.options, options || {});
	},
	//开始切换设置
	Start: function() {
		if(this.Index < 0){this.Index = this._count - 1;}
		else if (this.Index >= this._count){this.Index = 0; }
		
		this._target = -1 * this._parameter * this.Index;
		this.onStart();
		this.Move();
	},
	//移动
	Move: function() {
		clearTimeout(this._timer);
		var oThis = this, style = this.Up ? "top" : "left", iNow = parseInt(this._slider.style[style]) || 0, iStep = this.GetStep(this._target, iNow);
		
		if (iStep != 0) {
		   this._slider.style[style] = (iNow + iStep) + "px";
		   this._timer = setTimeout(function(){ oThis.Move(); }, this.Time);
		}
		else {
		   this._slider.style[style] = this._target + "px";
		   this.onFinish();
		   if (this.Auto) { this._timer = setTimeout(function(){ oThis.Index++; oThis.Start(); }, this.Pause); }
		}
	},
	//获取步长
	GetStep: function(iTarget, iNow) {
		var iStep = (iTarget - iNow) / this.Step;
		if (iStep == 0) return 0;
		if (Math.abs(iStep) < 1) return (iStep > 0 ? 1 : -1);
		return iStep;
	},
	//停止
	Stop: function(iTarget, iNow) {
		clearTimeout(this._timer);
		this._slider.style[this.Up ? "top" : "left"] = this._target + "px";
	}
};