Fixing scriptaculous’ slider

I needed a working slider component for my web application, and scriptaculous provides a component which “almost” works in my application.

Of course, you could say it doesn’t work. My application is built using equanda, and this allows client-side switching between display and edit mode of records. Unfortunately, the slider does not initialise correctly when hidden.
I have fixed this by passing the size of the crucial parts as parameters to the component instead (and then setting it on the objects) instead of querying the objects for their size.

Another (very minor) problem is that the component did not update my displayed value when just clicking. It works fine when dragging the control, but not when just clicking. Though this was actually because I listened only to the “onSlide” and not the “onChange” event, I personally believe it should still work.

Patched version :

// script.aculo.us slider.js v1.8.2, Tue Nov 18 18:30:58 +0100 2008

// Copyright (c) 2005-2008 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/

// slightly modified from original to assure the increment is used and to allow the slider to be initially hidden
// for this, two extra parameters "trackLength" and "handleLength" are introduced, which set the style of the elements.

if (!Control) var Control = { };

// options:
//  axis: 'vertical', or 'horizontal' (default)
//
// callbacks:
//  onChange(value)
//  onSlide(value)
Control.ckSlider = Class.create({
  initialize: function(handle, track, options) {
    var slider = this;

    if (Object.isArray(handle)) {
      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.trackLength = parseInt(this.options.trackLength || '200');
    this.handleLength = parseInt(this.options.handleLength || '5');

    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');

    if ( this.isVertical() )  {
        this.track.style.height=""+this.trackLength+"px";
        this.handles[0].style.height=""+this.handleLength+"px";
    } else {
        this.track.style.width=""+this.trackLength+"px"
        this.handles[0].style.width=""+this.handleLength+"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(
        (Object.isArray(slider.options.sliderValue) ?
          slider.options.sliderValue[i] : slider.options.sliderValue) ||
         slider.range.start), i);
      h.makePositioned().observe("mousedown", slider.eventMouseDown);
    });

    this.track.observe("mousedown", this.eventMouseDown);
    document.observe("mouseup", this.eventMouseUp);
    document.observe("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){
    value=Math.round(value/this.increment)*this.increment;
    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]);
  },
  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);
      if (Prototype.Browser.WebKit) 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.onSlide)
      this.options.onSlide(this.values.length>1 ? this.values : this.value, this);
    if (this.initialized && this.options.onChange)
      this.options.onChange(this.values.length>1 ? this.values : this.value, this);
    this.event = null;
  }
});

3 Comments

  1. Xinxua says:

    Awesome stuff! What I wanted exactly!

  2. I’ve had to modifying the slider.js file several times myself as it couldn’t correctly find the high and low values passed to it.

    I also used your modifications but then noticed that the current version of slider.js looks for width/height attributes on the slider and handle elements – so much for simply applying a class, now we have to add extra attributes individually. Still the result is quite impressive.

  3. IncludE says:

    Hi there !

    Any way to resize the height|width) of a instancied slider ?

    In my case, I’ve built a scrollbar who works with the resize window event 😉
    So, I call the dispose method, and build again a new instance.

    Some other ways to do this ?

    Thanks

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