BCGControlBar Pro for MFC
virtual double CBCGPChartAxis::ValueFromPoint ( const CBCGPPoint pt,
CBCGPChartAxis::RoundType  roundType = CBCGPChartAxis::RT_EXACT 

Given a point in client coordinates calculates corresponding axis value.

Call this function to calculate an axis value from point in client coordinates.

ptSpecifies a point in client coordinates.
roundTypeTells whether the value should be rounded to nearest major unit.