/*************************************************************************
	This code is from Dynamic Web Coding at dyn-web.com
	Copyright 2001-2008 by Sharon Paine 
	See Terms of Use at www.dyn-web.com/business/terms.php
	regarding conditions under which you may use this code.
	This notice must be retained in the code as is!
	
	version date: Aug 2008
*************************************************************************/

// horizId only needed for horizontal scrolling
function dw_scrollObj(wndoId, lyrId, horizId) {
	var wn = document.getElementById(wndoId);
	this.id = wndoId; dw_scrollObj.col[this.id] = this;
	this.animString = "dw_scrollObj.col." + this.id;
	this.load(lyrId, horizId);
	
	if (wn.addEventListener) {
		wn.addEventListener('DOMMouseScroll', dw_scrollObj.doOnMouseWheel, false);
	} 
	wn.onmousewheel = dw_scrollObj.doOnMouseWheel;
}

dw_scrollObj.isSupported = function () {
	if ( document.getElementById && document.getElementsByTagName 
		 && document.addEventListener || document.attachEvent ) {
		return true;
	}
	return false;
}

dw_scrollObj.col = {}; // collect instances
dw_scrollObj.defaultSpeed = dw_scrollObj.prototype.speed = 300; // default for mouseover or mousedown scrolling, was 100
dw_scrollObj.defaultSlideDur = dw_scrollObj.prototype.slideDur = 300; // default duration of glide onclick

// pseudo events 
dw_scrollObj.prototype.on_load = function() {} // when dw_scrollObj initialized or new layer loaded
dw_scrollObj.prototype.on_scroll = function() {}
dw_scrollObj.prototype.on_scroll_start = function() {}
dw_scrollObj.prototype.on_scroll_stop = function() {} // when scrolling has ceased (mouseout/up)
dw_scrollObj.prototype.on_scroll_end = function() {} // reached end
dw_scrollObj.prototype.on_update = function() {} // called in updateDims

dw_scrollObj.prototype.on_glidescroll = function() {}
dw_scrollObj.prototype.on_glidescroll_start = function() {}
dw_scrollObj.prototype.on_glidescroll_stop = function() {} // destination (to/by) reached
dw_scrollObj.prototype.on_glidescroll_end = function() {} // reached end

dw_scrollObj.prototype.load = function(lyrId, horizId) {
	var wndo, lyr;
	if (this.lyrId) { // layer currently loaded?
		lyr = document.getElementById(this.lyrId);
		lyr.style.visibility = "hidden";
	}
	this.lyr = lyr = document.getElementById(lyrId); // hold this.lyr?
	this.lyr.style.position = 'absolute'; 
	this.lyrId = lyrId; // hold id of currently visible layer
	this.horizId = horizId || null; // hold horizId for update fn
	wndo = document.getElementById(this.id);
	this.y = 0; this.x = 0; this.shiftTo(0,0);
	this.getDims(wndo, lyr); 
	lyr.style.visibility = "visible";
	this.ready = true; this.on_load(); 
}

dw_scrollObj.prototype.shiftTo = function(x, y) {
	if (this.lyr) {
		this.lyr.style.left = (this.x = x) + "px"; 
		this.lyr.style.top = (this.y = y) + "px";
	}
}

dw_scrollObj.prototype.getX = function() { return this.x; }
dw_scrollObj.prototype.getY = function() { return this.y; }

dw_scrollObj.prototype.getDims = function(wndo, lyr) { 
	this.wd = this.horizId? document.getElementById( this.horizId ).offsetWidth: lyr.offsetWidth;
	this.maxX = (this.wd - wndo.offsetWidth > 0)? this.wd - wndo.offsetWidth: 0;
	this.maxY = (lyr.offsetHeight - wndo.offsetHeight > 0)? lyr.offsetHeight - wndo.offsetHeight: 0;
}

dw_scrollObj.prototype.updateDims = function() {
	var wndo = document.getElementById(this.id);
	var lyr = document.getElementById( this.lyrId );
	this.getDims(wndo, lyr);
	this.on_update();
}

// for mouseover/mousedown scrolling
dw_scrollObj.prototype.initScrollVals = function(deg, speed) {
	if (!this.ready) return; 
	if (this.timerId) {
		clearInterval(this.timerId); this.timerId = 0;
	}
	this.speed = speed || dw_scrollObj.defaultSpeed;
	this.fx = (deg == 0)? -1: (deg == 180)? 1: 0;
	this.fy = (deg == 90)? 1: (deg == 270)? -1: 0;
	this.endX = (deg == 90 || deg == 270)? this.x: (deg == 0)? -this.maxX: 0; 
	this.endY = (deg == 0 || deg == 180)? this.y: (deg == 90)? 0: -this.maxY;
	this.lyr = document.getElementById(this.lyrId);
	this.lastTime = new Date().getTime();
	this.on_scroll_start(this.x, this.y);  
	this.timerId = setInterval(this.animString + ".scroll()", 10);    
}

dw_scrollObj.prototype.scroll = function() {
	var now = new Date().getTime();
	var d = (now - this.lastTime)/1000 * this.speed;
	if (d > 0) { 
		var x = this.x + Math.round(this.fx * d); var y = this.y + Math.round(this.fy * d);
		if ( ( this.fx == -1 && x > -this.maxX ) || ( this.fx == 1 && x < 0 ) || 
				( this.fy == -1 && y > -this.maxY ) || ( this.fy == 1 && y < 0 ) ) 
	   {
			this.lastTime = now;
			this.shiftTo(x, y);
			this.on_scroll(x, y);
		} else {
			clearInterval(this.timerId); this.timerId = 0;
			this.shiftTo(this.endX, this.endY);
			this.on_scroll(this.endX, this.endY);
			this.on_scroll_end(this.endX, this.endY);
		}
	}
}

// when scrolling has ceased (mouseout/up)
dw_scrollObj.prototype.ceaseScroll = function() {
	if (!this.ready) return;
	if (this.timerId) {
		clearInterval(this.timerId); this.timerId = 0; 
	}
	this.on_scroll_stop(this.x, this.y); 
}

// glide onclick scrolling
dw_scrollObj.prototype.initScrollByVals = function(dx, dy, dur) {
	if ( !this.ready || this.sliding ) return;
	this.startX = this.x; this.startY = this.y;
	this.destX = this.destY = this.distX = this.distY = 0;
	if (dy < 0) {
		this.distY = (this.startY + dy >= -this.maxY)? dy: -(this.startY  + this.maxY);
	} else if (dy > 0) {
		this.distY = (this.startY + dy <= 0)? dy: -this.startY;
	}
	if (dx < 0) {
		this.distX = (this.startX + dx >= -this.maxX)? dx: -(this.startX + this.maxX);
	} else if (dx > 0) {
		this.distX = (this.startX + dx <= 0)? dx: -this.startX;
	}
	this.destX = this.startX + this.distX; this.destY = this.startY + this.distY;
	this.glideScrollPrep(this.destX, this.destY, dur);
}

dw_scrollObj.prototype.initScrollToVals = function(destX, destY, dur) {
	if ( !this.ready || this.sliding ) return;
	this.startX = this.x; this.startY = this.y;
	this.destX = -Math.max( Math.min(destX, this.maxX), 0);
	this.destY = -Math.max( Math.min(destY, this.maxY), 0);
	this.distY = this.destY - this.startY;
	this.distX = this.destX - this.startX;
	this.glideScrollPrep(this.destX, this.destY, dur);
}

dw_scrollObj.prototype.glideScrollPrep = function(destX, destY, dur) {
	this.slideDur = (typeof dur == 'number')? dur: dw_scrollObj.defaultSlideDur;
	this.per = Math.PI/(2 * this.slideDur); this.sliding = true;
	this.lyr = document.getElementById(this.lyrId); 
	this.startTime = new Date().getTime();
	this.timerId = setInterval(this.animString + ".doGlideScroll()",10);
	this.on_glidescroll_start(this.startX, this.startY);
}

dw_scrollObj.prototype.doGlideScroll = function() {
	var elapsed = new Date().getTime() - this.startTime;
	if (elapsed < this.slideDur) {
		var x = this.startX + Math.round( this.distX * Math.sin(this.per*elapsed) );
		var y = this.startY + Math.round( this.distY * Math.sin(this.per*elapsed) );
		this.shiftTo(x, y); 
		this.on_glidescroll(x, y);
	} else {	// if time's up
		clearInterval(this.timerId); this.timerId = 0; this.sliding = false;
		this.shiftTo(this.destX, this.destY);
		this.on_glidescroll(this.destX, this.destY);
		this.on_glidescroll_stop(this.destX, this.destY);
		// end of axis reached ? 
		if ( this.distX && (this.destX == 0 || this.destX == -this.maxX) 
		  || this.distY && (this.destY == 0 || this.destY == -this.maxY) ) { 
			this.on_glidescroll_end(this.destX, this.destY);
		} 
	}
}

//  resource: http://adomas.org/javascript-mouse-wheel/
dw_scrollObj.handleMouseWheel = function(id, delta) {
	var wndo = dw_scrollObj.col[id];
	var x = wndo.x;
	var y = wndo.y;
	wndo.on_scroll_start(x,y);
	var ny;
	ny = 12  * delta + y
	ny = (ny < 0 && ny >= -wndo.maxY)? ny: (ny < -wndo.maxY)? -wndo.maxY: 0;
	wndo.shiftTo(x, ny);
	wndo.on_scroll(x, ny);
}

dw_scrollObj.doOnMouseWheel = function(e) {
	var delta = 0;
	if (!e) e = window.event;
	if (e.wheelDelta) { /* IE/Opera. */
		delta = e.wheelDelta/120;
		if (window.opera) delta = -delta;
	} else if (e.detail) { // Mozilla 
		delta = -e.detail/3;
	}
	if (delta) { // > 0 up, < 0 down
		dw_scrollObj.handleMouseWheel(this.id, delta);
	}
	if (e.preventDefault) e.preventDefault();
	e.returnValue = false;
}

dw_scrollObj.GeckoTableBugFix = function() {} // no longer need old bug fix


// Get position of el within layer (oCont) sOff: 'left' or 'top'
// Assumes el is within oCont
function dw_getLayerOffset(el, oCont, sOff) {
	var off = "offset" + sOff.charAt(0).toUpperCase() + sOff.slice(1);
	var val = el[off];
	while ( (el = el.offsetParent) != oCont ) 
		val += el[off];
	var clientOff = off.replace("offset", "client");
	if ( el[clientOff] ) val += el[clientOff];
	return val;
}