in src/visual.ts [314:321]
private getXAxisHeight(chartData: TableHeatMapChartData): number {
let maxLengthText: powerbi.PrimitiveValue = _.maxBy(chartData.categoryY, "length") || "";
return TextMeasurementService.measureSvgTextHeight({
fontSize: PixelConverter.toString(this.settings.xAxisLabels.fontSize),
text: maxLengthText.toString().trim(),
fontFamily: this.settings.xAxisLabels.fontFamily
});
}