// 一个简单的测试是否IE浏览器的表达式
isIE = (document.all ? true : false);

// 得到IE中各元素真正的位移量，即使这个元素在一个表格中
function getIEPosX(elt)
{
	return getIEPos(elt,"Left"); 
}

function getIEPosY(elt)
{
	return getIEPos(elt,"Top"); 
}

function getIEPos(elt,which) 
{
	iPos = 0
	while (elt!=null) 
	{
		iPos += elt["offset" + which]
		elt = elt.offsetParent
	}
	return iPos
}

function getXBrowserRef(eltname) 
{
	return (isIE ? document.all[eltname].style : document.layers[eltname]);
}

function hideElement(eltname)
{
	getXBrowserRef(eltname).visibility = 'hidden'; 
}

// 按不同的浏览器进行处理元件的位置
function moveBy(elt,deltaX,deltaY) 
{
	if (isIE) 
	{
		elt.left = elt.pixelLeft + deltaX;
		elt.top = elt.pixelTop + deltaY;
	}
	else 
	{
		elt.left += deltaX;
		elt.top += deltaY;
	}
}

function toggleVisible(eltname) 
{
	elt = getXBrowserRef(eltname);
	if (elt.visibility == 'visible' || elt.visibility == 'show') 
	{
		elt.visibility = 'hidden';
	} 
	else 
	{
		fixPosition(eltname);
		elt.visibility = 'visible';
	}
}

function setPosition(elt,positionername,isPlacedUnder) 
{
	positioner = null;
	if (isIE) 
	{
		positioner = document.all[positionername];
		elt.left = getIEPosX(positioner);
		elt.top = getIEPosY(positioner);
	}
	else 
	{
		positioner = document.images[positionername];
		elt.left = positioner.x;
		elt.top = positioner.y;
	}
	if (isPlacedUnder) 
	{
		moveBy(elt,0,positioner.height); 
	}
}



//——————————————————————————————————————

	// 判断浏览器
	isIE = (document.all ? true : false);

	// 初始月份及各月份天数数组
	var months = new Array("一　月", "二　月", "三　月", "四　月", "五　月", "六　月", "七　月",
							"八　月", "九　月", "十　月", "十一月", "十二月");
	var daysInMonth = new Array(31, 28, 31, 30, 31, 30, 31, 31,	30, 31, 30, 31);
	var displayMonth = new Date().getMonth();
	var displayYear = new Date().getFullYear();
	var displayDivName;
	var displayElement;

	function getDays(month, year) 
	{
		//测试选择的年份是否是润年？
		if (1 == month)
		{
			return ((0 == year % 4) && (0 != (year % 100))) ||
					(0 == year % 400) ? 29 : 28;
		}
		else
		{
			return daysInMonth[month];
		}
	}

	function getToday() 
	{
		// 得到今天的日期
		this.now = new Date();
		this.year = this.now.getFullYear();
		this.month = this.now.getMonth();
		this.day = this.now.getDate();
	}

	// 并显示今天这个月份的日历
	today = new getToday();

	function newCalendar(eltName,attachedElement) 
	{
		if (attachedElement)
		{
			if (displayDivName && displayDivName != eltName)
			{
				hideElement(displayDivName);
			}
			displayElement = attachedElement;
		}
		displayDivName = eltName;
		today = new getToday();
		var parseYear = parseInt(displayYear + '');
		var newCal = new Date(parseYear,displayMonth,1);
		var day = -1;
		var startDayOfWeek = newCal.getDay();
		if ((today.year == newCal.getFullYear()) &&
			  (today.month == newCal.getMonth()))
		{
		   day = today.day;
		}
		var intDaysInMonth = getDays(newCal.getMonth(), newCal.getFullYear());
		var daysGrid = makeDaysGrid(startDayOfWeek,day,intDaysInMonth,newCal,eltName)
		if (isIE) 
		{
			var elt = document.all[eltName];
			elt.innerHTML = daysGrid;
		}
		else 
		{
			var elt = document.layers[eltName].document;
			elt.open();
			elt.write(daysGrid);
			elt.close();
		}
	}

	function incMonth(delta,eltName) 
	{
		displayMonth += delta;
		if (displayMonth >= 12) 
		{
			displayMonth = 0;
			incYear(1,eltName);
		}
		else
		{
			if (displayMonth <= -1) 
			{
				displayMonth = 11;
				incYear(-1,eltName);
			}
			else 
			{
				newCalendar(eltName);
			}
		}
	}

	function incYear(delta,eltName) 
	{
		displayYear = parseInt(displayYear + '') + delta;
		newCalendar(eltName);
	}

	function makeDaysGrid(startDay,day,intDaysInMonth,newCal,eltName) 
	{
		var daysGrid;
		var month = newCal.getMonth();
		var year = newCal.getFullYear();
		var isThisYear = (year == new Date().getFullYear());
		var isThisMonth = (day > -1)

		daysGrid = '<table border=1 cellspacing=0 cellpadding=2><tr><td bgcolor=#ffffff nowrap>';
		daysGrid += '<font face="courier new, courier" size=2>';
		daysGrid += '<a href="javascript:hideElement(\'' + eltName + '\')">x</a>';
		daysGrid += '&nbsp;&nbsp;';
		daysGrid += '<a href="javascript:incMonth(-1,\'' + eltName + '\')">&laquo; </a>';

		daysGrid += '<b>';
		if (isThisMonth) 
		{
			daysGrid += '<font color=red>' + months[month] + '</font>'; 
		}
		else
		{
			daysGrid += months[month]; 
		}
		daysGrid += '</b>';

		daysGrid += '<a href="javascript:incMonth(1,\'' + eltName + '\')"> &raquo;</a>';
		daysGrid += '&nbsp;&nbsp;&nbsp;';
		daysGrid += '<a href="javascript:incYear(-1,\'' + eltName + '\')">&laquo; </a>';

		daysGrid += '<b>';
		if (isThisYear)
		{
			daysGrid += '<font color=red>' + year + '</font>'; 
		}
		else
		{
			daysGrid += ''+year; 
		}
		daysGrid += '</b>';

		daysGrid += '<a href="javascript:incYear(1,\'' + eltName + '\')"> &raquo;</a><br>';
		daysGrid += '&nbsp;Su Mo Tu We Th Fr Sa&nbsp;<br>&nbsp;';
		var dayOfMonthOfFirstSunday = (7 - startDay + 1);
		for (var intWeek = 0; intWeek < 6; intWeek++) 
		{
			var dayOfMonth;
			for (var intDay = 0; intDay < 7; intDay++) 
			{
				dayOfMonth = (intWeek * 7) + intDay + dayOfMonthOfFirstSunday - 7;
				if (dayOfMonth <= 0) 
				{
					daysGrid += "&nbsp;&nbsp; ";
				}
				else
				{
					if (dayOfMonth <= intDaysInMonth) 
					{
						var color = "blue";
						if (day > 0 && day == dayOfMonth)
						{
							color="red";
						}
						daysGrid += '<a href="javascript:setDay(';
						daysGrid += dayOfMonth + ',\'' + eltName + '\')" '
						daysGrid += 'style="color:' + color + '">';
						var dayString = dayOfMonth + "</a> ";
						if (dayString.length == 6) 
						{
							dayString = '0' + dayString;
						}
						daysGrid += dayString;
					}
				}
			}
			if (dayOfMonth < intDaysInMonth)
			{
				daysGrid += "<br>&nbsp;";
			}
		}
		return daysGrid + "</td></tr></table>";
	}

	function setDay(day,eltName) 
	{
		displayDay = day;
		if (day < 10)
		{
			displayDay = "0" + day;
		}
		dispMonth = displayMonth + 1
		if (dispMonth < 10)
		{
			dispMonth = "0" + dispMonth;
		}
		displayElement.value = displayYear + "-" + dispMonth + "-" + displayDay;
		hideElement(eltName);
	}


//——————————————————————————————————————

// fixPosition() 这个函数和前面所讲的那个函数一样
//
function fixPosition(eltname) 
{
	elt = getXBrowserRef(eltname);
	positionerImgName = eltname + 'Pos';
	// hint: try setting isPlacedUnder to false
	isPlacedUnder = false;
	if (isPlacedUnder) 
	{
		setPosition(elt,positionerImgName,true);
	}
	else 	
	{
		setPosition(elt,positionerImgName)
	}
}

function toggleDatePicker(eltName,formElt) 
{
	var x = formElt.indexOf('.');
	var formName = formElt.substring(0,x);
	var formEltName = formElt.substring(x+1);
	newCalendar(eltName,document.forms[formName].elements[formEltName]);
	toggleVisible(eltName);
}

// fixPositions() 这个函数前面也讲过
function fixPositions()
{
	fixPosition('daysOfMonth');
	fixPosition('daysOfMonth2');
}