Showing Mouse Axis Coordinates on Chart Control

Question

Is there a simple way to retrieve the X/Y coordinates of ANY point in the chart Area (relative to that chart Axis of course)?

As of now, I just managed to retrieve coordinates when the mouse is on a Series (not outside)

private void chart_GetToolTipText(object sender, ToolTipEventArgs e)
{
    if (e.HitTestResult.Series != null)
    {
        e.Text = e.HitTestResult.Series.Points[e.HitTestResult.PointIndex].YValues[0] + " \n " + DateTime.FromOADate(e.HitTestResult.Series.Points[e.HitTestResult.PointIndex].XValue);
    }
}

Answer 1

This works for my purposes and doesn't side effect the cursor.

private Tuple<double,double> GetAxisValuesFromMouse(int x, int y)
{
    var chartArea = _chart.ChartAreas[0];
    var xValue = chartArea.AxisX.PixelPositionToValue(x);
    var yValue = chartArea.AxisY.PixelPositionToValue(y);
    return new Tuple<double, double>(xValue, yValue);
}

Answer 2

Anyway, as always with MS Chart Controls, there is no easy way to do things,
but a funky workaround to get things done. I am sadly getting used to it...

private void chart1_MouseWhatever(object sender, MouseEventArgs e)
{
    chartArea1.CursorX.SetCursorPixelPosition(new Point(e.X, e.Y), true);
    chartArea1.CursorY.SetCursorPixelPosition(new Point(e.X, e.Y), true);

    double pX = chartArea1.CursorX.Position; //X Axis Coordinate of your mouse cursor
    double pY = chartArea1.CursorY.Position; //Y Axis Coordinate of your mouse cursor
}

Answer 3

I tried your answer, but it didn't work for me. It ended up putting the cursor in one spot and never moving. I believe this is because I use decimal/double values along both axes, and the cursor is being rounded to the nearest integer.

After several attempts, I was able to work out a method for determining where the cursor is inside the chart. The hard part was figuring out that all the "positions" for the chart elements are actually percentage values (from 0 to 100).

As per
http://msdn.microsoft.com/en-us/library/system.windows.forms.datavisualization.charting.elementposition.aspx:
"Defines the position of the chart element in relative coordinates, which range from (0,0) to (100,100)."

I hope you don't mind, I am posting this answer here just for posterity, in case anyone else comes across this problem, and your method also does not work for them. Its not pretty or elegant in any way, but so far it works for me.

private struct PointD
{
  public double X;
  public double Y;
  public PointD(double X, double Y)
  {
    this.X = X;
    this.Y = Y;
  }
}

private void chart1_MouseMove(object sender, MouseEventArgs e)
{
  var pos = LocationInChart(e.X, e.Y);
  lblCoords.Text = string.Format("({0}, {1}) ... ({2}, {3})", e.X, e.Y, pos.X, pos.Y);
}

private PointD LocationInChart(double xMouse, double yMouse)
{
  var ca = chart1.ChartAreas[0];

  //Position inside the control, from 0 to 100
  var relPosInControl = new PointD
  (
    ((double)xMouse / (double)execDetailsChart.Width) * 100,
    ((double)yMouse / (double)execDetailsChart.Height) * 100
  );

  //Verify we are inside the Chart Area
  if (relPosInControl.X < ca.Position.X || relPosInControl.X > ca.Position.Right
  || relPosInControl.Y < ca.Position.Y || relPosInControl.Y > ca.Position.Bottom) return new PointD(double.NaN, double.NaN);

  //Position inside the Chart Area, from 0 to 100
  var relPosInChartArea = new PointD
  (
    ((relPosInControl.X - ca.Position.X) / ca.Position.Width) * 100,
    ((relPosInControl.Y - ca.Position.Y) / ca.Position.Height) * 100
  );

  //Verify we are inside the Plot Area
  if (relPosInChartArea.X < ca.InnerPlotPosition.X || relPosInChartArea.X > ca.InnerPlotPosition.Right
  || relPosInChartArea.Y < ca.InnerPlotPosition.Y || relPosInChartArea.Y > ca.InnerPlotPosition.Bottom) return new PointD(double.NaN, double.NaN);

  //Position inside the Plot Area, 0 to 1
  var relPosInPlotArea = new PointD
  (
    ((relPosInChartArea.X - ca.InnerPlotPosition.X) / ca.InnerPlotPosition.Width),
    ((relPosInChartArea.Y - ca.InnerPlotPosition.Y) / ca.InnerPlotPosition.Height)
  );

  var X = relPosInPlotArea.X * (ca.AxisX.Maximum - ca.AxisX.Minimum) + ca.AxisX.Minimum;
  var Y = (1 - relPosInPlotArea.Y) * (ca.AxisY.Maximum - ca.AxisY.Minimum) + ca.AxisY.Minimum;

  return new PointD(X, Y);
}