/*   dw_scroll.js    version date: Feb 2004    */

/*************************************************************************
  This code is from Dynamic Web Coding at http://www.dyn-web.com/
  Copyright 2001-4 by Sharon Paine 
  See Terms of Use at http://www.dyn-web.com/bus/terms.html
  regarding conditions under which you may use this code.
  This notice must be retained in the code as is!
*************************************************************************/

dw_scrollLayers = {};
dw_scrollLayer.speed = 100; // default speed for mouseover scrolling
//  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.shiftTo = function(lyr, x, y) {
  lyr.style.left = (this.x = x) + "px"; 
  lyr.style.top = (this.y = y) + "px";
}

// functions for onmouseover scrolling 
// algorithm for time-based scrolling from youngpup.net

// called onmouseover. arguments: direction (possible values: 'up', 'down', 'left', 'right')
// speed (optional) to override default speed (set in dw_scrollLayer.speed)
dw_scrollLayer.prototype.startScroll = function(dir, speed) {
  if (!this.ready) return; if (this.timerId) clearInterval(this.timerId);
  this.speed = speed || dw_scrollLayer.speed;
  this.lyr = document.getElementById(this.lyrId);
  if (dir == "up" || dir == "down") {
    this.xdir = 0; this.endX = parseInt(this.lyr.style.left);
    this.ydir = (dir == "down")? -1: 1; this.endY = (dir == "down")? -this.maxY: 0;
  } else if (dir == "right" || dir == "left") {
    this.ydir = 0; this.endY = parseInt(this.lyr.style.top);
    this.xdir = (dir == "right")? -1: 1; this.endX = (dir == "right")? -this.maxX: 0;
  } else {
    alert("Up, down, left, and right are the only scroll directions currently supported.");
    return; 
  }
  this.lastTime = ( new Date() ).getTime();
  this.on_scroll_start();  
  this.timerId = setInterval(this.animString + ".scroll()", 10); 
}

dw_scrollLayer.prototype.scroll = function() {
  var now = ( new Date() ).getTime();
  var x = this.x + this.xdir * (now - this.lastTime)/1000 * this.speed;
  var y = this.y + this.ydir * (now - this.lastTime)/1000 * this.speed;
  if ( ( this.xdir == -1 && x > -this.maxX ) || ( this.xdir == 1 && x < 0 ) || 
    ( this.ydir == -1 && y > -this.maxY ) || ( this.ydir == 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);
  }
}

dw_scrollLayer.prototype.stopScroll = function() {
  if (!this.ready) return;
  if (this.timerId) clearInterval(this.timerId);
  this.timerId = 0;  this.lyr = null;
}
  
dw_scrollLayer.prototype.on_scroll = function() {}
dw_scrollLayer.prototype.on_scroll_start = function() {}
dw_scrollLayer.prototype.on_scroll_end = function() {}
  
// 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 ) {
    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, holder, x, y;
  if (dw_scrollLayer.hold) {
    for (i=0; dw_scrollLayer.hold[i]; i++) {
      wndo = document.getElementById( dw_scrollLayer.hold[i][0] );
      holder = document.getElementById( dw_scrollLayer.hold[i][1] );
      x = holder.offsetLeft; y = holder.offsetTop;
      wndo.style.left = x + "px"; wndo.style.top = y + "px";
    }
  }
}