zoom = function(scaleVal) {

            var $image = _this.core.$outer.find('.lg-current .lg-image');
            var _x;
            var _y;

            // Find offset manually to avoid issue after zoom
            var offsetX = ($(window).width() - $image.width()) / 2;
            var offsetY = (($(window).height() - $image.height()) / 2) + $(window).scrollTop();

            _x = _this.pageX - offsetX;
            _y = _this.pageY - offsetY;

            var x = (scaleVal - 1) * (_x);
            var y = (scaleVal - 1) * (_y);

            $image.css('transform', 'scale3d(' + scaleVal + ', ' + scaleVal + ', 1)').attr('data-scale', scaleVal);

            $image.parent().css({
                left: -x + 'px',
                top: -y + 'px'
            }).attr('data-x', x).attr('data-y', y);
        }
@desc Image zoom
Translate the wrap and scale the image to get better user experience

@param {String} scaleVal - Zoom decrement/increment value