User:Emma/common.js: Difference between revisions

Revision as of 01:56, February 3, 2012

/*
Class: Scroller
    Adds a scrollbar to a specific div. The scrollbar is implemented using a Script.aculo.us slider.
    The class reparents the original div, creates a slider and ties the reparented div to the slider,
    setting any properties necessary on the divs to make it all work. The scrollbar can be styled using
    CSS. The track of the scrollbar has class 'scroll-track', 'scroll-track-top' and 'scroll-track-bot',
    the thumb has class 'scroll-handle', 'scroll-handle-top' and 'scroll-handle-bot'.
    
properties:
    myIndex - an integer used to generate a unique ID for use in, for example, div ids.
    outerBox - the div that holds the scrollpane + scrollbar
    innerBox - the div that holds the scrollpane
    innerHeight - the height of the inner box.
    viewportHeight - the height of the view onto the scrolled div.
    track - a div that holds the script.aculo.us slider (the scrollbar)
    trackHeight - the height of the slider
    handle - the div for the 'thumb' of the scrollbar
    handleHeight - the height of the thumb
    slider - the script.aculo.us slider itself
    ieDecreaseBy - a fudge factor used when calculating the width of innerBox
    
*/
var Scroller = Class.create();

/*
property: Scroller.ids
    A cache of Scrollers indexed by the ID of the original div.
 */
Scroller.ids = new Object();

/*
property: Scroller.i
    A unique ID generator.
 */
Scroller.i = 0;

Scroller.prototype = {
    /*
    constructor: initialize 
        Wrap the passed div in a scrollpane.
    
    parameters: 
        el - the div to add a scrollbar to.
     */
  initialize: function(el) {
    this.outerBox = el;
    this.decorate();
  },
  
  /*
  function: decorate  
    create the necessary elements to implement the scrollbar and wire up events.
   */
  decorate: function() {
    $(this.outerBox).makePositioned(); // Fix IE
    
    // Seed a unique ID
    Scroller.i = Scroller.i + 1;
    this.myIndex = Scroller.i;
    
    //wrap the existing content in an intermediate inner box
    this.innerBox = document.createElement("DIV");
    this.innerBox.className="scroll-innerBox";
    $(this.innerBox).makePositioned();  // Fix IE
    this.innerBox.style.cssFloat=this.innerBox.style.styleFloat='left'; // Need the scrollbar to appear next to the scrollpane
    this.innerBox.id="scroll-innerBox-"+Scroller.i;
    this.innerBox.style.top = "0px";
    
    //Transfer the contents of Outer Box to Inner Box
    while (this.outerBox.hasChildNodes()) {
        this.innerBox.appendChild(this.outerBox.firstChild);
    }
    this.innerBox.style.overflow="hidden";
    //turn off scrolling on the outer div
    this.outerBox.style.overflow="hidden";

    // create a track
    this.track=document.createElement('div');
    this.track.className="scroll-track";
    $(this.track).makePositioned();
    this.track.style.cssFloat=this.track.style.styleFloat='left';
    this.track.id="scroll-track-"+Scroller.i;
    // Fix IE line-height bug. Sigh.
    this.track.appendChild(document.createComment(''));

    // Create the top button
    this.tracktop=document.createElement('div');
    this.tracktop.className="scroll-track-top";
    $(this.tracktop).makePositioned();
    this.tracktop.style.cssFloat=this.tracktop.style.styleFloat='left';
    this.tracktop.id="scroll-track-top-"+Scroller.i;
    // Fix IE line-height bug. Sigh.
    this.tracktop.appendChild(document.createComment(''));
    
    // Create the bottom button
    this.trackbot=document.createElement('div');
    this.trackbot.className="scroll-track-bot";
    $(this.trackbot).makePositioned();
    this.trackbot.style.cssFloat=this.trackbot.style.styleFloat='left';
    this.trackbot.id="scroll-track-bot-"+Scroller.i;
    // Fix IE line-height bug. Sigh.
    this.trackbot.appendChild(document.createComment(''));

    // Create the handle
    this.handle=document.createElement('div');
    this.handle.className="scroll-handle-container";
    this.handle.id="scroll-handle-container"+Scroller.i;

    // Create the handle middle
    this.handle_middle=document.createElement('div');
    this.handle_middle.className="scroll-handle";
    $(this.handle_middle).makePositioned();
    this.handle_middle.id="scroll-handle-"+Scroller.i;
    // Fix IE line-height bug. Sigh.
    this.handle_middle.appendChild(document.createComment(''));

    // Create the handle top cap
    this.handletop=document.createElement('div');
    this.handletop.className="scroll-handle-top";
    $(this.handletop).makePositioned();
    this.handletop.id="scroll-handle-top-"+Scroller.i;
    // Fix IE line-height bug. Sigh.
    this.handletop.appendChild(document.createComment(''));

    // Create the handle bottom cap
    this.handlebot=document.createElement('div');
    this.handlebot.className="scroll-handle-bot";
    $(this.handlebot).makePositioned();
    this.handlebot.id="scroll-handle-bot-"+Scroller.i;
    // Fix IE line-height bug. Sigh.
    this.handlebot.appendChild(document.createComment(''));

    this.track.hide();
    this.tracktop.hide();
    this.trackbot.hide();

    this.outerBox.appendChild(this.innerBox);
    this.outerBox.appendChild(this.tracktop);
    this.handle.appendChild(this.handletop);
    this.handle.appendChild(this.handle_middle);
    this.handle.appendChild(this.handlebot);
    this.track.appendChild(this.handle);
    this.outerBox.appendChild(this.track);
    this.outerBox.appendChild(this.trackbot);

    this.slider = new Control.Slider($(this.handle).id, $(this.track).id, {axis:'vertical',
                                     minimum: 0,
                                     maximum: $(this.outerBox).clientHeight});
    this.slider.options.onSlide = this.slider.options.onChange = this.onChange.bind(this);
    setTimeout(this.resetScrollbar.bind(this, false), 10);

    this.domMouseCB = this.MouseWheelEvent.bindAsEventListener(this, this.slider);
    this.mouseWheelCB = this.MouseWheelEvent.bindAsEventListener(this, this.slider);
    this.trackTopCB = this.tracktopEvent.bindAsEventListener(this, this.slider);
    this.trackBotCB = this.trackbotEvent.bindAsEventListener(this, this.slider);
    
    //Events control
    $(this.outerBox).observe('DOMMouseScroll', this.domMouseCB); // Mozilla
    $(this.outerBox).observe('mousewheel', this.mouseWheelCB);// IE/Opera
    $(this.tracktop).observe('mousedown', this.trackTopCB);
    $(this.trackbot).observe('mousedown', this.trackBotCB);
  },
  
  release: function() {
    $(this.outerBox).stopObserving('DOMMouseScroll', this.domMouseCB);
    $(this.outerBox).stopObserving('mousewheel', this.mouseWheelCB);// IE/Opera
    $(this.tracktop).stopObserving('mousedown', this.trackTopCB);
    $(this.trackbot).stopObserving('mousedown', this.trackBotCB);
  },
  
  /*
  function: resetScrollbar  
    Re-calculate the geometry of the scrollbar. Typically called from an event handler.
    
    args:   
        repeat - if true, set timer to re-calculate to fix IE bug on resize window.
   */
  resetScrollbar: function(repeat) {
        this.track.hide();
        this.tracktop.hide();
        this.trackbot.hide();
        this.enableScroll = false;
        this.innerHeight = $(this.outerBox).clientHeight;
        this.innerBox.style.height = this.innerHeight + "px";
        var newWidth = $(this.outerBox).clientWidth;

        var tth = Element.getStyle(this.tracktop,"height");
        if (tth)
           tth = tth.replace("px","");
        else
           tth = 0;
    
        var hth = Element.getStyle(this.handletop,"height");
        if (hth)
           hth = hth.replace("px","");
        else
           hth = 0;
    
        if (this.innerHeight < this.innerBox.scrollHeight) {
            this.viewportHeight = this.innerHeight - tth*2;
            this.slider.trackLength = this.viewportHeight;
            this.track.style.height = this.viewportHeight + "px";       
            this.handleHeight = Math.round(this.viewportHeight * this.innerHeight / this.innerBox.scrollHeight);    
            if(this.handleHeight < (hth*2))
                this.handleHeight = (hth*2);
            if (this.handleHeight < 10)
                 this.handleHeight = 10;
            this.handle.style.height = this.handleHeight + "px";
            this.handle_middle.style.height = this.handleHeight - hth*2 + "px";
            this.handletop.style.height = hth + "px";
            this.slider.handleLength = this.handleHeight;
            this.track.style.display = 'inline';
            this.tracktop.style.display = 'inline';
            this.trackbot.style.display = 'inline';
            this.ieDecreaseBy = 1;   // Firefox seems to have an off-by one error, so allow for it.
            if (this.outerBox.currentStyle) {
                var borderWidth = this.outerBox.currentStyle["borderWidth"].replace("px","");
                if(!isNaN(borderWidth)) {
                    this.ieDecreaseBy = (borderWidth) * 2;
                }
            }
            newWidth = ($(this.outerBox).clientWidth - $(this.track).clientWidth - this.ieDecreaseBy);
            this.enableScroll = true;
        }
        //Set the width of of the scrollpane (aka innerBox).
        this.innerBox.style.width = newWidth + "px";
        //Fix IE resize event Bug 
        if(repeat) {
            setTimeout(this.resetScrollbar.bind(this, false), 10);
        }
  },
  
    //Mouse wheel code from http://adomas.org/javascript-mouse-wheel/
    MouseWheelEvent: function(event, slider) {
        var delta = 0;
        if (!event) //For IE.
            event = window.event;
        if (event.wheelDelta) { //IE/Opera.
            delta = event.wheelDelta / 120;
            /*if (window.opera) //In Opera 9, delta differs in sign as compared to IE
                delta = -delta;   But it isn't necessary with Opera v9.51*/
        } else if (event.detail) { //Mozilla case
            delta = -event.detail / 3;
        }
        if (delta)
            slider.setValueBy(-delta / 10);
        Event.stop(event);
    },

    trackbotEvent: function(event, slider) {
        if (Event.isLeftClick(event)) { 
            slider.setValueBy(0.2);
            Event.stop(event);
        }
    },

    tracktopEvent: function(event, slider) {
        if (Event.isLeftClick(event)) {
            slider.setValueBy(-0.2);
            Event.stop(event);
        }
    },

  /*
  function: onChange  
    Called when the script.aculo.us slider has changed (i.e. when it has been dragged). Scroll the inner box.
    
    args:   
        val - not used.
   */
    onChange: function(val) {
        if(this.enableScroll)
            this.innerBox.scrollTop = Math.round (val * (this.innerBox.scrollHeight-this.innerBox.offsetHeight));
    }
}

/*
function: Scroller.setAll
    Search for divs of the class 'makeScroll' and wrap them in a Scroller.
 */
Scroller.setAll = function () {
    $$('.makeScroll').each(function(item) {
        Scroller.ids[item.id] = new Scroller(item);
    });
}

/*
function: Scroller.reset
    If the passed element has class 'makeScroll', wrap it in a Scroller.
 */
Scroller.reset = function (body_id) {
    if ($(body_id).className.match(new RegExp("(^|\\s)makeScroll(\\s|$)"))) {
       if (Scroller.ids[body_id])
           Scroller.ids[body_id].release();
           
        Scroller.ids[body_id] = new Scroller($(body_id));
    }
}

/*
property: Scroller.updateAll
    Reset all of the scrollbars.
 */
Scroller.updateAll = function () {
    $H(Scroller.ids).each(function(pair) {
        Scroller.ids[pair.key].resetScrollbar(true);
    });
}

/*
    Hook up some global event handlers.
 */
Event.observe(window, "load", Scroller.setAll);
Event.observe(window, "resize", Scroller.updateAll);