time - (dimensions.width * chartOptions.millisPerPixel),
        valueToYPixel = function(value) {
          var offset = value - this.currentVisMinValue;
          return this.currentValueRange === 0
            ? dimensions.height
            : dimensions.height - (Math.round((offset / this.currentValueRange) * dimensions.height));
        }.bind(this),
        timeToXPixel = function(t) {
          if(chartOptions.scrollBackwards) {
            return Math.round((time - t) / chartOptions.millisPerPixel);