dw_scrollObj.stopScroll = function(wnId) {
  if ( dw_scrollObjs[wnId] ) dw_scrollObjs[wnId].endScroll();
}

dw_scrollObj.initScroll = function(wnId, deg, sp) {
  if ( dw_scrollObjs[wnId] ) {
    var cosine, sine;
    if (typeof deg == "string") {
      switch (deg) {
        case "up"    : deg = 90;  break;
        case "down"  : deg = 270; break;
       }
    } 
   
	  cosine=0;
	  dw_scrollObjs[wnId].fx=0; 
		  	  
	  if (deg==90) { 
	  	sine=1;
    	 dw_scrollObjs[wnId].fy = 1;
		}
	  else if (deg==270){
		sine=-1;
     	 dw_scrollObjs[wnId].fy = -1;
	  }
	  else {
		  sine=0;
	  }
    dw_scrollObjs[wnId].endX = (deg == 90 || deg == 270)? dw_scrollObjs[wnId].x:
      (deg < 90 || deg > 270)? -dw_scrollObjs[wnId].maxX: 0; 
    dw_scrollObjs[wnId].endY = (deg == 0 || deg == 180)? dw_scrollObjs[wnId].y: 
      (deg < 180)? 0: -dw_scrollObjs[wnId].maxY;
    dw_scrollObjs[wnId].startScroll(sp);
  }
}

dw_scrollObj.prototype.startScroll = function(speed) {
  if (!this.ready) return; if (this.timerId) clearInterval(this.timerId);
  this.speed = speed || dw_scrollObj.speed;
  this.lyr = document.getElementById(this.lyrId);
  this.lastTime = ( new Date() ).getTime();
  this.on_scroll_start();  
  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 + this.fx * d; var y = this.y + this.fy * d;
    if (this.fx == 0 || this.fy == 0) { 
      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(this.lyr, x, y);
        this.on_scroll(x, y);
      } else {
        clearInterval(this.timerId); this.timerId = 0;
        this.shiftTo(this.lyr, this.endX, this.endY);
        this.on_scroll_end(this.endX, this.endY);
      }
    } else {
      if ( ( this.fx < 0 && x >= -this.maxX && this.fy < 0 && y >= -this.maxY ) ||
        ( this.fx > 0 && x <= 0 && this.fy > 0 && y <= 0 ) ||
        ( this.fx < 0 && x >= -this.maxX && this.fy > 0 && y <= 0 ) ||
        ( this.fx > 0 && x <= 0 && this.fy < 0 && y >= -this.maxY ) ) {
        this.lastTime = now;
        this.shiftTo(this.lyr, x, y);
        this.on_scroll(x, y);
      } else {
        clearInterval(this.timerId); this.timerId = 0;
        this.on_scroll_end(this.x, this.y);
      }
    }
  }
}

dw_scrollObj.prototype.endScroll = function() {
  if (!this.ready) return;
  if (this.timerId) clearInterval(this.timerId);
  this.timerId = 0;  this.lyr = null;
}

dw_scrollObj.prototype.on_scroll = function() {}
dw_scrollObj.prototype.on_scroll_start = function() {}
dw_scrollObj.prototype.on_scroll_end = function() {}
dw_scrollObjs = {};
dw_scrollObj.speed = 50; 
function dw_scrollObj(wnId, lyrId, cntId) {
  this.id = wnId; dw_scrollObjs[this.id] = this;
  this.animString = "dw_scrollObjs." + this.id;
  this.load(lyrId, cntId);
}


dw_scrollObj.prototype.load = 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_scrollObj.prototype.on_load = function() {}  

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