//dw_glidescroll.js   version date: March 2004   */

dw_scrollLayers = {};
dw_scrollLayer.slideDur = 500; // duration of glide
//  constructor arguments: id of layer containing scrolling layers (clipped layer), id of layer to scroll, 
//	id of table or other element that scrolling content is nested in 
//	ns6+/moz need that extra container to get width for horizontal scrolling.
//	(not needed for vertical scrolling)
function dw_scrollLayer(wnId, lyrId, cntId) {
  this.id = wnId; dw_scrollLayers[this.id] = this;
  this.animString = "dw_scrollLayers." + this.id;
  this.loadLayer(lyrId, cntId);
}

dw_scrollLayer.prototype.loadLayer = function(lyrId, cntId) {
  if (!document.getElementById) return;
  var wndo, lyr;
  if (this.lyrId) {
    lyr = document.getElementById(this.lyrId);
    lyr.style.visibility = "hidden";
  }
  lyr = document.getElementById(lyrId);
  wndo = document.getElementById(this.id);
  lyr.style.top = this.y = 0; lyr.style.left = this.x = 0;
  this.maxY = (lyr.offsetHeight - wndo.offsetHeight > 0)? lyr.offsetHeight - wndo.offsetHeight: 0;
  this.wd = cntId? document.getElementById(cntId).offsetWidth: lyr.offsetWidth;
  this.maxX = (this.wd - wndo.offsetWidth > 0)? this.wd - wndo.offsetWidth: 0;
  this.lyrId = lyrId; // hold id of currently visible layer
  lyr.style.visibility = "visible";
  this.on_load(); this.ready = true;
}

dw_scrollLayer.prototype.on_load = function() {}
dw_scrollLayer.prototype.on_slide_start = function() {}
dw_scrollLayer.prototype.on_slide = function() {}
dw_scrollLayer.prototype.on_slide_end = function() {}

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

// functions for glide-scroll onclick 

// Resources for time-based slide algorithm: 
//  DHTML chaser tutorial at DHTML Lab - www.webreference.com/dhtml	
//  and cbe_slide.js from	www.cross-browser.com by Mike Foster
dw_scrollLayer.prototype.glideScrollBy = function(dx, dy, dur) {
  if ( !document.getElementById || this.sliding ) return;
  this.slideDur = dur || dw_scrollLayer.slideDur;
  this.destX = this.destY = this.distX = this.distY = 0;
  this.lyr = document.getElementById(this.lyrId);
  this.startX = this.x; this.startY = this.y;
  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.slideTo(this.destX, this.destY);
}


dw_scrollLayer.prototype.glideScrollTo = function(destX, destY, dur) {
  if ( !document.getElementById || this.sliding ) return;
  this.slideDur = dur || dw_scrollLayer.slideDur;
  this.lyr = document.getElementById(this.lyrId); 
  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.slideTo(this.destX, this.destY);
}

dw_scrollLayer.prototype.slideTo = function(destX, destY) {
  this.per = Math.PI/(2 * this.slideDur); this.sliding = true;
	this.slideStart = (new Date()).getTime();
	this.aniTimer = setInterval(this.animString + ".doSlide()",10);
  this.on_slide_start(this.startX, this.startY);
}

dw_scrollLayer.prototype.doSlide = function() {
	var elapsed = (new Date()).getTime() - this.slideStart;
	if (elapsed < this.slideDur) {
		var x = this.startX + this.distX * Math.sin(this.per*elapsed);
		var y = this.startY + this.distY * Math.sin(this.per*elapsed);
    this.shiftTo(this.lyr, x, y); this.on_slide(x, y);
	} else {	// if time's up
    clearInterval(this.aniTimer); this.sliding = false;
		this.shiftTo(this.lyr, this.destX, this.destY);
    this.lyr = null; this.on_slide_end(this.destX, this.destY);
	}
}

// remove layers from table for ns6+/mozilla (needed for scrolling inside tables)
function GeckoTableBugFix() {
  var i, wndo, holderId, holder, x, y;
	if ( navigator.userAgent.indexOf("Gecko") > -1 && navigator.userAgent.indexOf("Firefox") == -1 ) {
    dw_scrollLayer.hold = []; // holds id's of wndo and its container
    for (i=0; arguments[i]; i++) {
      if ( dw_scrollLayers[arguments[i]] ) {
        wndo = document.getElementById(arguments[i]);
        holderId = wndo.parentNode.id;
        holder = document.getElementById(holderId);
        document.body.appendChild( holder.removeChild(wndo) );
        wndo.style.zIndex = 1000;
        x = holder.offsetLeft; y = holder.offsetTop;
        wndo.style.left = x + "px"; wndo.style.top = y + "px";
        dw_scrollLayer.hold[i] = [arguments[i], holderId];
      }
    }
   window.addEventListener("resize", rePositionGecko, true);
  }
}

// ns6+/mozilla need to reposition layers onresize when scrolling inside tables.
function rePositionGecko() {
  var i, wndo, pt, x, y;
  if (dw_scrollLayer.hold) {
    for (i=0; dw_scrollLayer.hold[i]; i++) {
      wndo = document.getElementById( dw_scrollLayer.hold[i][0] );
      pt = document.getElementById( dw_scrollLayer.hold[i][1] );
      x = pt.offsetLeft; y = pt.offsetTop;
      wndo.style.left = x + "px"; wndo.style.top = y + "px";
    }
  }
}