highcharts scroll

gistfile1.txt

H.addEvent(chart.container, document.onmousewheel === undefined ? 'DOMMouseScroll' : 'mousewheel', function (event) {

                var delta, extr, step, newMin, newMax, axis = chart.xAxis[0];
                var dataMax = chart.xAxis[0].dataMax,
                    dataMin = chart.xAxis[0].dataMin,
                    maxCategory = (chart.xAxis[0].categories.length < 26) ? 26 : chart.xAxis[0].categories.length,
                    currentViewMin = 0,
                    newExtrMin,
                    newExtrMax;

                e = chart.pointer.normalize(event);
                // Firefox uses e.detail, WebKit and IE uses wheelDelta
                delta = e.detail || -(e.wheelDelta / 120);
                delta = delta < 0 ? -1 : 1;

                if (chart.isInsidePlot(e.chartX - chart.plotLeft, e.chartY - chart.plotTop)) {
                    extr = axis.getExtremes();
                    step = (extr.max - extr.min) / 5 * delta;                    

                    (extr.min <= 0 && step < 0) ? step = 0 : step = step;

                    /*if ((extr.min + step) <= dataMin) {
                        newExtrMin = dataMin;
                        newExtrMax = extr.max;
                    } else if ((extr.max + step) >= dataMax) {
                        newExtrMin = (extr.max === dataMax) ? extr.min : extr.min + step; //condition is if scrolling is at the end of X axis
                        newExtrMax = dataMax;
                    } else {*/
                    if(maxCategory <= 26) {
                        newExtrMin = extr.min;
                        newExtrMax = extr.max;
                    } else {
                        newExtrMin = extr.min + step;
                        newExtrMax = extr.max + step;
                    }

                    currentViewMin = Math.round(newExtrMax-newExtrMin) - 26;

                    // current min value is not 0 means current view is not having 26 cat
                    (currentViewMin !== 0) ? newExtrMin = newExtrMax - 26 : '';
                    
                    (newExtrMin < currentViewMin) ? newExtrMin = extr.min : '';
                    (newExtrMax > maxCategory) ? newExtrMax = extr.max : '';
                    // }

                    axis.setExtremes(newExtrMin, newExtrMax, true, false); //setExtremes( [newMin] [, newMax] [, redraw] [, animation] [, eventArguments])

                }

                stopEvent(event); // Issue #5011, returning false from non-jQuery event does not prevent default
                return false;
            });