/*************************************************************************
  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 = 100; // default for mouseover or mousedown scrolling
dw_scrollObj.defaultSlideDur = dw_scrollObj.prototype.slideDur = 500; // 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;
  }