chadicus / test-helpers

(function (factory) {

        // AMD. Register as an anonymous module.

        define(['jquery'], factory);

    } else if (typeof exports === 'object') {

        // Node/CommonJS style for Browserify

        module.exports = factory;

    } else {

        // Browser globals

        factory(jQuery);

    }

}(function ($) {

    var toFix  = ['wheel', 'mousewheel', 'DOMMouseScroll', 'MozMousePixelScroll'],

        toBind = ( 'onwheel' in document || document.documentMode >= 9 ) ?

                    ['wheel'] : ['mousewheel', 'DomMouseScroll', 'MozMousePixelScroll'],

        slice  = Array.prototype.slice,

        nullLowestDeltaTimeout, lowestDelta;

    if ( $.event.fixHooks ) {

        for ( var i = toFix.length; i; ) {

            $.event.fixHooks[ toFix[--i] ] = $.event.mouseHooks;

        }

    }

    var special = $.event.special.mousewheel = {

        version: '3.1.9',

        setup: function() {

            if ( this.addEventListener ) {

                for ( var i = toBind.length; i; ) {

                    this.addEventListener( toBind[--i], handler, false );

                }

            } else {

                this.onmousewheel = handler;

            }

            // Store the line height and page height for this particular element

            $.data(this, 'mousewheel-line-height', special.getLineHeight(this));

            $.data(this, 'mousewheel-page-height', special.getPageHeight(this));

        },

        teardown: function() {

            if ( this.removeEventListener ) {

                for ( var i = toBind.length; i; ) {

                    this.removeEventListener( toBind[--i], handler, false );

                }

            } else {

                this.onmousewheel = null;

            }

        },

        getLineHeight: function(elem) {

            return parseInt($(elem)['offsetParent' in $.fn ? 'offsetParent' : 'parent']().css('fontSize'), 10);

        },

        getPageHeight: function(elem) {

            return $(elem).height();

        },

        settings: {

            adjustOldDeltas: true

        }

    };

    $.fn.extend({

        mousewheel: function(fn) {

            return fn ? this.bind('mousewheel', fn) : this.trigger('mousewheel');

        },

        unmousewheel: function(fn) {

            return this.unbind('mousewheel', fn);

        }

    });

    function handler(event) {

        var orgEvent   = event || window.event,

            args       = slice.call(arguments, 1),

            delta      = 0,

            deltaX     = 0,

            deltaY     = 0,

            absDelta   = 0;

        event = $.event.fix(orgEvent);

        event.type = 'mousewheel';

        // Old school scrollwheel delta

        if ( 'detail'      in orgEvent ) { deltaY = orgEvent.detail * -1;      }

        if ( 'wheelDelta'  in orgEvent ) { deltaY = orgEvent.wheelDelta;       }

        if ( 'wheelDeltaY' in orgEvent ) { deltaY = orgEvent.wheelDeltaY;      }

        if ( 'wheelDeltaX' in orgEvent ) { deltaX = orgEvent.wheelDeltaX * -1; }

        // Firefox < 17 horizontal scrolling related to DOMMouseScroll event

        if ( 'axis' in orgEvent && orgEvent.axis === orgEvent.HORIZONTAL_AXIS ) {

            deltaX = deltaY * -1;

            deltaY = 0;

        }

        // Set delta to be deltaY or deltaX if deltaY is 0 for backwards compatabilitiy

        delta = deltaY === 0 ? deltaX : deltaY;

        // New school wheel delta (wheel event)

        if ( 'deltaY' in orgEvent ) {

            deltaY = orgEvent.deltaY * -1;

            delta  = deltaY;

        }

        if ( 'deltaX' in orgEvent ) {

            deltaX = orgEvent.deltaX;

            if ( deltaY === 0 ) { delta  = deltaX * -1; }

        }

        // No change actually happened, no reason to go any further

        // Need to convert lines and pages to pixels if we aren't already in pixels

        // There are three delta modes:

        //   * deltaMode 0 is by pixels, nothing to do

        //   * deltaMode 1 is by lines

        //   * deltaMode 2 is by pages

        if ( orgEvent.deltaMode === 1 ) {

            var lineHeight = $.data(this, 'mousewheel-line-height');

            delta  *= lineHeight;

            deltaY *= lineHeight;

            deltaX *= lineHeight;

        } else if ( orgEvent.deltaMode === 2 ) {

            var pageHeight = $.data(this, 'mousewheel-page-height');

            delta  *= pageHeight;

            deltaY *= pageHeight;

            deltaX *= pageHeight;

        }

        // Store lowest absolute delta to normalize the delta values

        absDelta = Math.max( Math.abs(deltaY), Math.abs(deltaX) );

        if ( !lowestDelta || absDelta < lowestDelta ) {

            lowestDelta = absDelta;

            // Adjust older deltas if necessary

            if ( shouldAdjustOldDeltas(orgEvent, absDelta) ) {

                lowestDelta /= 40;

            }

        }

        // Adjust older deltas if necessary

        if ( shouldAdjustOldDeltas(orgEvent, absDelta) ) {

            // Divide all the things by 40!

            delta  /= 40;

            deltaX /= 40;

            deltaY /= 40;

        }

        // Get a whole, normalized value for the deltas

        delta  = Math[ delta  >= 1 ? 'floor' : 'ceil' ](delta  / lowestDelta);

        deltaX = Math[ deltaX >= 1 ? 'floor' : 'ceil' ](deltaX / lowestDelta);

        deltaY = Math[ deltaY >= 1 ? 'floor' : 'ceil' ](deltaY / lowestDelta);

        // Add information to the event object

        event.deltaX = deltaX;

        event.deltaY = deltaY;

        event.deltaFactor = lowestDelta;

        // Go ahead and set deltaMode to 0 since we converted to pixels

        // Although this is a little odd since we overwrite the deltaX/Y

        // properties with normalized deltas.

        event.deltaMode = 0;

        // Add event and delta to the front of the arguments

        args.unshift(event, delta, deltaX, deltaY);

        // Clearout lowestDelta after sometime to better

        // handle multiple device types that give different

        // a different lowestDelta

        // Ex: trackpad = 3 and mouse wheel = 120

        if (nullLowestDeltaTimeout) { clearTimeout(nullLowestDeltaTimeout); }

        nullLowestDeltaTimeout = setTimeout(nullLowestDelta, 200);

        return ($.event.dispatch || $.event.handle).apply(this, args);

    }

    function nullLowestDelta() {

        lowestDelta = null;

    }

    function shouldAdjustOldDeltas(orgEvent, absDelta) {

        // If this is an older event and the delta is divisable by 120,

        // then we are assuming that the browser is treating this as an

        // older mouse wheel event and that we should divide the deltas

        // by 40 to try and get a more usable deltaFactor.

        // Side note, this actually impacts the reported scroll distance

        // in older browsers and can cause scrolling to be slower than native.

        // Turn this off by setting $.event.special.mousewheel.settings.adjustOldDeltas to false.

        return special.settings.adjustOldDeltas && orgEvent.type === 'mousewheel' && absDelta % 120 === 0;

    }

}));