Thanks for writing and for the provided screenshot.
With a custom label renderer you will have to calculate this behavior by yourself. For example, you could make the following estimation:
1. If the neighbouring data points of the current data point have a bigger Y axis value of the current data point - draw the label below the data point.
2. If the neighbouring data points of the current data point have a smaller Y axis value of the current data point - draw the label above the data point.
3. If the left/right data point's value is bigger/smaller draw the current data point's label floating to the right/left of the data point itself.
I hope this is helpful.
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