I'm afraid that HeatMap does not support Smart Labels functionality. Please have in mind that the heat map control has no notion of axes and the row and column headers are similar to the headers of a data-grid.
You can use LabelInterval
property of HeatMapColumnHeaderSettings if this works for you scenario:
I cannot see from the picture if the bottom labels represent Integers or DateTime. However, if you think in the context of the ChartView, the headers in heatmap are more like categories in a categorical axes, so you can set label interval, but you cannot have "SmartStep" (all categories are equal).
I hope this information helps. Let us know if you have any other questions.
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