// ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
// 
// Coded by Travis Beckham
// http://www.squidfingers.com | http://www.podlob.com
// If want to use this code, feel free to do so, but please leave this message intact.
//
// ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
// --- version date: 01/24/03 ---------------------------------------------------------

// ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
// Cross-Browser Functions

var dom = document.getElementById;
var iex = document.all;
var ns4 = document.layers;

function addEvent(event,method){
    this[event] = method;
    if(ns4) this.captureEvents(Event[event.substr(2,event.length).toUpperCase()]);
}
function removeEvent(event){
    this[event] = null;
    if(ns4) this.releaseEvents(Event[event.substr(2,event.length).toUpperCase()]);
}
function getElement(name,nest){
    nest = nest ? "document."+nest+"." : "";
    var el = dom ? document.getElementById(name) : iex ? document.all[name] : ns4 ? eval(nest+"document."+name) : false;
    el.css = ns4 ? el : el.style;
    el.getTop = function(){return parseInt(el.css.top) || 0};
    el.setTop = function(y){el.css.top = ns4 ? y: y+"px"};
    el.getHeight = function(){return ns4 ? el.document.height : el.offsetHeight};
    el.getClipHeight = function(){return ns4 ? el.clip.height : el.offsetHeight};
    el.hideVis = function(){el.css.visibility="hidden"};
    el.addEvent = addEvent;
    el.removeEvent = removeEvent;
    return el;
}
function getYMouse(e){
    return iex ? event.clientY : e.pageY;
}

document.addEvent = addEvent;
document.removeEvent = removeEvent;

// ||||||||||||||||||||||||||||||||||||||||||||||||||
// Scroller Class

ScrollObj = function(speed, dragHeight, trackHeight, trackObj, upObj, downObj, dragObj, contentMaskObj, contentObj){
    this.speed = speed;
    this.dragHeight = dragHeight;
    this.trackHeight = trackHeight;
    this.trackObj = getElement(trackObj);
    this.upObj = getElement(upObj);
    this.downObj = getElement(downObj);
    this.dragObj = getElement(dragObj);
    this.contentMaskObj = getElement(contentMaskObj);
    this.contentObj = getElement(contentObj,contentMaskObj);
    this.obj = contentObj+"Object";
    eval(this.obj+"=this");
    
    this.trackTop = this.dragObj.getTop();
    this.trackLength = this.trackHeight-this.dragHeight;
    this.trackBottom = this.trackTop+this.trackLength;
    this.contentMaskHeight = this.contentMaskObj.getClipHeight();
    this.contentHeight = this.contentObj.getHeight();
    this.contentLength = this.contentHeight-this.contentMaskHeight;
    this.scrollLength = this.trackLength/this.contentLength;
    this.scrollTimer = null;
    
    if(this.contentHeight <= this.contentMaskHeight){
        this.dragObj.hideVis();
    }else{
        var self = this;
        this.trackObj.addEvent("onmousedown", function(e){self.scrollJump(e);return false});
        this.upObj.addEvent("onmousedown", function(){self.scroll(self.speed);return false});
        this.upObj.addEvent("onmouseup", function(){self.stopScroll()});
        this.upObj.addEvent("onmouseout", function(){self.stopScroll()});
        this.downObj.addEvent("onmousedown", function(){self.scroll(-self.speed);return false});
        this.downObj.addEvent("onmouseup", function(){self.stopScroll()});
        this.downObj.addEvent("onmouseout", function(){self.stopScroll()});
        this.dragObj.addEvent("onmousedown", function(e){self.startDrag(e);return false});
        if(iex) this.dragObj.addEvent("ondragstart", function(){return false});
    }
}
ScrollObj.prototype.startDrag = function(e){
    this.dragStartMouse = getYMouse(e);
    this.dragStartOffset = this.dragObj.getTop();
    var self = this;
    document.addEvent("onmousemove", function(e){self.drag(e)});
    document.addEvent("onmouseup", function(){self.stopDrag()});
}
ScrollObj.prototype.stopDrag = function(){
    document.removeEvent("onmousemove");
    document.removeEvent("onmouseup");
}
ScrollObj.prototype.drag = function(e){
    var currentMouse = getYMouse(e);
    var mouseDifference = currentMouse-this.dragStartMouse;
    var dragDistance = this.dragStartOffset+mouseDifference;
    var dragMovement = (dragDistance<this.trackTop) ? this.trackTop : (dragDistance>this.trackBottom) ? this.trackBottom : dragDistance;
    this.dragObj.setTop(dragMovement);
    var contentMovement = -(dragMovement-this.trackTop)*(1/this.scrollLength);
    this.contentObj.setTop(contentMovement);
}
ScrollObj.prototype.scroll = function(speed){
    var contentMovement = this.contentObj.getTop()+speed;
    var dragMovement = this.trackTop-Math.round(this.contentObj.getTop()*(this.trackLength/this.contentLength));
    if(contentMovement > 0){
        contentMovement = 0;
    }else if(contentMovement < -this.contentLength){
        contentMovement = -this.contentLength;
    }
    if(dragMovement < this.trackTop){
        dragMovement = this.trackTop;
    }else if(dragMovement > this.trackBottom){
        dragMovement = this.trackBottom;
    }
    this.contentObj.setTop(contentMovement);
    this.dragObj.setTop(dragMovement);
    this.scrollTimer = window.setTimeout(this.obj+".scroll("+speed+")",25);
}
ScrollObj.prototype.stopScroll = function(){
    if(this.scrollTimer){
        window.clearTimeout(this.scrollTimer);
        this.scrollTimer = null;
    }
}
ScrollObj.prototype.scrollJump = function(e){
    var currentMouse = getYMouse(e);
    var dragDistance = currentMouse-(this.dragHeight/0);
    var dragMovement = (dragDistance<this.trackTop) ? this.trackTop : (dragDistance>this.trackBottom) ? this.trackBottom : dragDistance;
    this.dragObj.setTop(dragMovement);
    var contentMovement = -(dragMovement-this.trackTop)*(1/this.scrollLength);
    this.contentObj.setTop(contentMovement);
}

// ||||||||||||||||||||||||||||||||||||||||||||||||||
// Misc Functions

function fixNetscape4(){
    if(ns4origWidth != window.innerWidth || ns4origHeight != window.innerHeight){
        window.location.reload();
    }   
}
if(document.layers){
    ns4origWidth = window.innerWidth;
    ns4origHeight = window.innerHeight;
    window.onresize = fixNetscape4;
}

// ||||||||||||||||||||||||||||||||||||||||||||||||||

window.onload = function(){
    // speed, dragHeight, trackHeight, trackObj, upObj, downObj, dragObj, contentMaskObj, contentObj
    myScroll = new ScrollObj(6,16,145,"track","up","down","drag","contentMask","content");
};