text: // script.aculo.us slider.js v1.7.0_beta2, Mon Dec 18 23:38:56 CET 2006
  
  // Copyright (c) 2005, 2006 Marty Haught, Thomas Fuchs 
  //
  // script.aculo.us is freely distributable under the terms of an MIT-style license.
  // For details, see the script.aculo.us web site: http://script.aculo.us/
  
  if(!Control) var Control = {};
  Control.Slider = Class.create();
  
  // options:
  //  axis: 'vertical', or 'horizontal' (default)
  //
  // callbacks:
  //  onChange(value)
  //  onSlide(value)
  Control.Slider.prototype = {
    initialize: function(handle, track, options) {
      var slider = this;
      
      if(handle instanceof Array) {
        this.handles = handle.collect( function(e) { return $(e) });
      } else {
        this.handles = [$(handle)];
      }
      
      this.track   = $(track);
      this.options = options || {};
  
      this.axis      = this.options.axis || 'horizontal';
      this.increment = this.options.increment || 1;
      this.step      = parseInt(this.options.step || '1');
      this.range     = this.options.range || $R(0,1);
      
      this.value     = 0; // assure backwards compat
      this.values    = this.handles.map( function() { return 0 });
      this.spans     = this.options.spans ? this.options.spans.map(function(s){ return $(s) }) : false;
      this.options.startSpan = $(this.options.startSpan || null);
      this.options.endSpan   = $(this.options.endSpan || null);
  
      this.restricted = this.options.restricted || false;
  
      this.maximum   = this.options.maximum || this.range.end;
      this.minimum   = this.options.minimum || this.range.start;
  
      // Will be used to align the handle onto the track, if necessary
      this.alignX = parseInt(this.options.alignX || '0');
      this.alignY = parseInt(this.options.alignY || '0');
      
      this.trackLength = this.maximumOffset() - this.minimumOffset();
  
      this.handleLength = this.isVertical() ? 
        (this.handles[0].offsetHeight != 0 ? 
          this.handles[0].offsetHeight : this.handles[0].style.height.replace(/px$/,"")) : 
        (this.handles[0].offsetWidth != 0 ? this.handles[0].offsetWidth : 
          this.handles[0].style.width.replace(/px$/,""));
  
      this.active   = false;
      this.dragging = false;
      this.disabled = false;
  
      if(this.options.disabled) this.setDisabled();
  
      // Allowed values array
      this.allowedValues = this.options.values ? this.options.values.sortBy(Prototype.K) : false;
      if(this.allowedValues) {
        this.minimum = this.allowedValues.min();
        this.maximum = this.allowedValues.max();
      }
  
      this.eventMouseDown = this.startDrag.bindAsEventListener(this);
      this.eventMouseUp   = this.endDrag.bindAsEventListener(this);
      this.eventMouseMove = this.update.bindAsEventListener(this);
  
      // Initialize handles in reverse (make sure first handle is active)
      this.handles.each( function(h,i) {
        i = slider.handles.length-1-i;
        slider.setValue(parseFloat(
          (slider.options.sliderValue instanceof Array ? 
            slider.options.sliderValue[i] : slider.options.sliderValue) || 
           slider.range.start), i);
        Element.makePositioned(h); // fix IE
        Event.observe(h, "mousedown", slider.eventMouseDown);
      });
      
      Event.observe(this.track, "mousedown", this.eventMouseDown);
      Event.observe(document, "mouseup", this.eventMouseUp);
      Event.observe(document, "mousemove", this.eventMouseMove);
      
      this.initialized = true;
    },
    dispose: function() {
      var slider = this;    
      Event.stopObserving(this.track, "mousedown", this.eventMouseDown);
      Event.stopObserving(document, "mouseup", this.eventMouseUp);
      Event.stopObserving(document, "mousemove", this.eventMouseMove);
      this.handles.each( function(h) {
        Event.stopObserving(h, "mousedown", slider.eventMouseDown);
      });
    },
    setDisabled: function(){
      this.disabled = true;
    },
    setEnabled: function(){
      this.disabled = false;
    },  
    getNearestValue: function(value){
      if(this.allowedValues){
        if(value >= this.allowedValues.max()) return(this.allowedValues.max());
        if(value <= this.allowedValues.min()) return(this.allowedValues.min());
        
        var offset = Math.abs(this.allowedValues[0] - value);
        var newValue = this.allowedValues[0];
        this.allowedValues.each( function(v) {
          var currentOffset = Math.abs(v - value);
          if(currentOffset <= offset){
            newValue = v;
            offset = currentOffset;
          } 
        });
        return newValue;
      }
      if(value > this.range.end) return this.range.end;
      if(value < this.range.start) return this.range.start;
      return value;
    },
    setValue: function(sliderValue, handleIdx){
      if(!this.active) {
        this.activeHandleIdx = handleIdx || 0;
        this.activeHandle    = this.handles[this.activeHandleIdx];
        this.updateStyles();
      }
      handleIdx = handleIdx || this.activeHandleIdx || 0;
      if(this.initialized && this.restricted) {
        if((handleIdx>0) && (sliderValue<this.values[handleIdx-1]))
          sliderValue = this.values[handleIdx-1];
        if((handleIdx < (this.handles.length-1)) && (sliderValue>this.values[handleIdx+1]))
          sliderValue = this.values[handleIdx+1];
      }
      sliderValue = this.getNearestValue(sliderValue);
      this.values[handleIdx] = sliderValue;
      this.value = this.values[0]; // assure backwards compat
      
      this.handles[handleIdx].style[this.isVertical() ? 'top' : 'left'] = 
        this.translateToPx(sliderValue);
      
      this.drawSpans();
      if(!this.dragging || !this.event) this.updateFinished();
    },
    setValueBy: function(delta, handleIdx) {
      this.setValue(this.values[handleIdx || this.activeHandleIdx || 0] + delta, 
        handleIdx || this.activeHandleIdx || 0);
    },
    translateToPx: function(value) {
      return Math.round(
        ((this.trackLength-this.handleLength)/(this.range.end-this.range.start)) * 
        (value - this.range.start)) + "px";
    },
    translateToValue: function(offset) {
      return ((offset/(this.trackLength-this.handleLength) * 
        (this.range.end-this.range.start)) + this.range.start);
    },
    getRange: function(range) {
      var v = this.values.sortBy(Prototype.K); 
      range = range || 0;
      return $R(v[range],v[range+1]);
    },
    minimumOffset: function(){
      return(this.isVertical() ? this.alignY : this.alignX);
    },
    maximumOffset: function(){
      return(this.isVertical() ? 
        (this.track.offsetHeight != 0 ? this.track.offsetHeight :
          this.track.style.height.replace(/px$/,"")) - this.alignY : 
        (this.track.offsetWidth != 0 ? this.track.offsetWidth : 
          this.track.style.width.replace(/px$/,"")) - this.alignY);
    },  
    isVertical:  function(){
      return (this.axis == 'vertical');
    },
    drawSpans: function() {
      var slider = this;
      if(this.spans)
        $R(0, this.spans.length-1).each(function(r) { slider.setSpan(slider.spans[r], slider.getRange(r)) });
      if(this.options.startSpan)
        this.setSpan(this.options.startSpan,
          $R(0, this.values.length>1 ? this.getRange(0).min() : this.value ));
      if(this.options.endSpan)
        this.setSpan(this.options.endSpan, 
          $R(this.values.length>1 ? this.getRange(this.spans.length-1).max() : this.value, this.maximum));
    },
    setSpan: function(span, range) {
      if(this.isVertical()) {
        span.style.top = this.translateToPx(range.start);
        span.style.height = this.translateToPx(range.end - range.start + this.range.start);
      } else {
        span.style.left = this.translateToPx(range.start);
        span.style.width = this.translateToPx(range.end - range.start + this.range.start);
      }
    },
    updateStyles: function() {
      this.handles.each( function(h){ Element.removeClassName(h, 'selected') });
      Element.addClassName(this.activeHandle, 'selected');
    },
    startDrag: function(event) {
      if(Event.isLeftClick(event)) {
        if(!this.disabled){
          this.active = true;
          
          var handle = Event.element(event);
          var pointer  = [Event.pointerX(event), Event.pointerY(event)];
          var track = handle;
          if(track==this.track) {
            var offsets  = Position.cumulativeOffset(this.track); 
            this.event = event;
            this.setValue(this.translateToValue( 
             (this.isVertical() ? pointer[1]-offsets[1] : pointer[0]-offsets[0])-(this.handleLength/2)
            ));
            var offsets  = Position.cumulativeOffset(this.activeHandle);
            this.offsetX = (pointer[0] - offsets[0]);
            this.offsetY = (pointer[1] - offsets[1]);
          } else {
            // find the handle (prevents issues with Safari)
            while((this.handles.indexOf(handle) == -1) && handle.parentNode) 
              handle = handle.parentNode;
              
            if(this.handles.indexOf(handle)!=-1) {
              this.activeHandle    = handle;
              this.activeHandleIdx = this.handles.indexOf(this.activeHandle);
              this.updateStyles();
              
              var offsets  = Position.cumulativeOffset(this.activeHandle);
              this.offsetX = (pointer[0] - offsets[0]);
              this.offsetY = (pointer[1] - offsets[1]);
            }
          }
        }
        Event.stop(event);
      }
    },
    update: function(event) {
     if(this.active) {
        if(!this.dragging) this.dragging = true;
        this.draw(event);
        // fix AppleWebKit rendering
        if(navigator.appVersion.indexOf('AppleWebKit')>0) window.scrollBy(0,0);
        Event.stop(event);
     }
    },
    draw: function(event) {
      var pointer = [Event.pointerX(event), Event.pointerY(event)];
      var offsets = Position.cumulativeOffset(this.track);
      pointer[0] -= this.offsetX + offsets[0];
      pointer[1] -= this.offsetY + offsets[1];
      this.event = event;
      this.setValue(this.translateToValue( this.isVertical() ? pointer[1] : pointer[0] ));
      if(this.initialized && this.options.onSlide)
        this.options.onSlide(this.values.length>1 ? this.values : this.value, this);
    },
    endDrag: function(event) {
      if(this.active && this.dragging) {
        this.finishDrag(event, true);
        Event.stop(event);
      }
      this.active = false;
      this.dragging = false;
    },  
    finishDrag: function(event, success) {
      this.active = false;
      this.dragging = false;
      this.updateFinished();
    },
    updateFinished: function() {
      if(this.initialized && this.options.onChange) 
        this.options.onChange(this.values.length>1 ? this.values : this.value, this);
      this.event = null;
    }
  }