/*************************************************************************
 This code is from Dynamic Web Coding at www.dyn-web.com
 Copyright 2001-4 by Sharon Paine 
 See Terms of Use at 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_hoverscroll.js version date: June 2004 
  mouseover scrolling for dw_scrollObj (in dw_scrollObj.js) */

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

// increase speed onmousedown of scroll links
dw_scrollObj.doubleSpeed = function(wnId) {
 if ( dw_scrollObjs[wnId] ) dw_scrollObjs[wnId].speed *= 2;
}

dw_scrollObj.resetSpeed = function(wnId) {
 if ( dw_scrollObjs[wnId] ) dw_scrollObjs[wnId].speed /= 2;
}

// algorithms for time-based scrolling and scrolling onmouseover at any angle adapted from youngpup.net
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;
    case "left" : deg = 180; break;
    case "right" : deg = 0;  break;
    default: 
     alert("Direction of scroll in mouseover scroll links should be 'up', 'down', 'left', 'right' or number: 0 to 360.");
    }
  } 
  deg = deg % 360;
  if (deg % 90 == 0) {
   cosine = (deg == 0)? -1: (deg == 180)? 1: 0;
   sine = (deg == 90)? 1: (deg == 270)? -1: 0;
  } else {
   var angle = deg * Math.PI/180;
   cosine = -Math.cos(angle); sine = Math.sin(angle);
  }
  dw_scrollObjs[wnId].fx = cosine / ( Math.abs(cosine) + Math.abs(sine) );
  dw_scrollObjs[wnId].fy = sine / ( Math.abs(cosine) + Math.abs(sine) );
  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);
 }
}

// speed (optional) to override default speed (set in dw_scrollObj.speed)
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) { // for horizontal or vertical scrolling
   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 { // for scrolling at an angle (stop when reach end on one axis)
   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() {}