void Chart1_MouseMove(object sender, MouseEventArgs e) { ChartGroup grp = Chart1.ChartGroups.Group0; ps = grp.ChartData.PointStylesList[0]; // if both are changed to valid values, then something needs to be highlighted int seriesIndex = -1, pointIndex = -1; // check if the mouse is in the PlotArea. if (Chart1.ChartRegionFromCoord(e.X, e.Y) == ChartRegionEnum.PlotArea) { int dist = 0; // find the closest XCoord. if (grp.CoordToDataIndex(e.X, e.Y, CoordinateFocusEnum.XCoord, ref seriesIndex, ref pointIndex, ref dist)) { // if there are multiple series in the chart, then find the closest series. if (grp.CoordToSeriesIndex(e.X, e.Y, PlotElementEnum.Series, ref seriesIndex, ref dist)) { ps.PointIndex = pointIndex; ps.SeriesIndex = seriesIndex; label3.Text = tlist[pointIndex].ToString(); label4.Text = ylist[pointIndex].ToString(); } } if (seriesIndex == -1 || pointIndex == -1) { ps.PointIndex = -1; ps.SeriesIndex = -1; } } }