//** jQuery Scroll to Top Control script- (c) Dynamic Drive DHTML code library: http://www.dynamicdrive.com.
//** Available/ usage terms at http://www.dynamicdrive.com (March 30th, 09')
//** v1.1 (April 7th, 09'):
//** 1) Adds ability to scroll to an absolute position (from top of page) or specific element on the page instead.
//** 2) Fixes scroll animation not working in Opera. 
//** 2014/3/27 modified for Magic3 by naoki.
var scrolltotop={
	//startline: Integer. Number of pixels from top of doc scrollbar is scrolled before showing control
	//scrollto: Keyword (Integer, or "Scroll_to_Element_ID"). How far to scroll document up when control is clicked on (0=top).
	setting: {startline:100, scrollto: 0, scrollduration:1000, fadeduration:[500, 100]},
	controlHTML: '<img src="up.png" style="width:48px; height:48px" />', //HTML for control, which is auto wrapped in DIV w/ ID="topcontrol"
	controlattrs: {offsetx:5, offsety:5}, //offset of control relative to right/ bottom of window corner
	anchorkeyword: '#top', //Enter href value of HTML anchors on the page that should also act as "Scroll Up" links

	state: { isvisible:false, shouldvisible:false },

	scrollup:function(){
		if (!this.cssfixedsupport){	//if control is positioned using JavaScript
			this.$control.css({opacity:0}); //hide control immediately after clicking it
		}
		var dest=isNaN(this.setting.scrollto)? this.setting.scrollto : parseInt(this.setting.scrollto);
		if (typeof dest=="string" && $('#'+dest).length==1){	 //check element set by string exists
			dest=$('#'+dest).offset().top;
		} else {
			dest=0;
		}
		this.$body.animate({scrollTop: dest}, this.setting.scrollduration);
	},

	keepfixed:function(){
		var $window=$(window);
		var controlx=$window.scrollLeft() + $window.width() - this.$control.width() - this.controlattrs.offsetx;
		var controly=$window.scrollTop() + $window.height() - this.$control.height() - this.controlattrs.offsety;
		this.$control.css({left:controlx+'px', top:controly+'px'});
	},

	togglecontrol:function(){
		var scrolltop=$(window).scrollTop();
		if (!this.cssfixedsupport) this.keepfixed();
		this.state.shouldvisible=(scrolltop>=this.setting.startline) ? true : false;
		if (this.state.shouldvisible && !this.state.isvisible){
			this.$control.stop().animate({opacity:1}, this.setting.fadeduration[0]);
			this.state.isvisible=true;
		} else if (this.state.shouldvisible==false && this.state.isvisible){
			this.$control.stop().animate({opacity:0}, this.setting.fadeduration[1]);
			this.state.isvisible=false;
		}
	},

	init:function(options){
		// パラメータ初期化
		if (options.setting) this.setting = options.setting;
		if (options.controlHTML) this.controlHTML = options.controlHTML;
		if (options.controlattrs) this.controlattrs = options.controlattrs;
		if (options.anchorkeyword) this.anchorkeyword = options.anchorkeyword;
		
		//var mainobj=scrolltotop;
		var mainobj=this;
		var iebrws=document.all;
		mainobj.cssfixedsupport=!iebrws || iebrws && document.compatMode=="CSS1Compat" && window.XMLHttpRequest;	//not IE or IE7+ browsers in standards mode
		mainobj.$body=(window.opera)? (document.compatMode=="CSS1Compat"? $('html') : $('body')) : $('html,body');
		mainobj.$control=$('<div id="topcontrol">'+mainobj.controlHTML+'</div>')
			.css({position:mainobj.cssfixedsupport? 'fixed' : 'absolute', bottom:mainobj.controlattrs.offsety, right:mainobj.controlattrs.offsetx, opacity:0, cursor:'pointer'})
			.attr({title:'Scroll Back to Top'})
			.click(function(){ mainobj.scrollup(); return false; })
			.appendTo('body');
		if (document.all && !window.XMLHttpRequest && mainobj.$control.text()!=''){	//loose check for IE6 and below, plus whether control contains any text
			mainobj.$control.css({width:mainobj.$control.width()});		//IE6- seems to require an explicit width on a DIV containing text
		}
		mainobj.togglecontrol();
		$('a[href="' + mainobj.anchorkeyword +'"]').click(function(){
			mainobj.scrollup();
			return false;
		});
		$(window).bind('scroll resize', function(e){
			mainobj.togglecontrol();
		});
	}
}
