Show values in C# Chart Points

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Hello everyone!

The question is if it's possible to show a point's value of a c# chart when i'm with the cursor line over it.

For example this:

https://www.dropbox.com/s/ruynlkah2n259id/cursor%201.png[^]

This point is on the 53% of the scale but i don't know his real value(if, for example was from 0 to 999).

Thanks beforehead.

Regards.

Posted 11-Aug-13 23:18pm

Acusu

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2 solutions

Solution 1

Well, if scale is known, then it is very easy to compute the point actual value, e.g.
53% on 0-999 scale is 529 (int((999-0)/100*53)).

Posted 11-Aug-13 23:24pm

CPallini

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Acusu 12-Aug-13 5:28am

Thanks for the response, but what i want to do is show this value in a tooltip, for example, when the mouse is over that point

CPallini 12-Aug-13 5:33am

Then you have to get mouse position, transform it into position in graph and eventually transform the latter into actual (X,Y) values. The two transformations are really simple (translation and scale).

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Acusu · Accepted Answer · 2013-08-12T01:20:00

Thanks CPallini, the solution was in the coordinates. I found this, if it's useful for anyone else.

Regards!
----------------------------------------------------------------------------------------------------

C#

Point? prevPosition = null;
ToolTip tooltip = new ToolTip();

void chart1_MouseMove(object sender, MouseEventArgs e)
{
    var pos = e.Location;
    if (prevPosition.HasValue && pos == prevPosition.Value)
        return;
    tooltip.RemoveAll();
    prevPosition = pos;
    var results = chart1.HitTest(pos.X, pos.Y, false,
                                    ChartElementType.DataPoint);
    foreach (var result in results)
    {
        if (result.ChartElementType == ChartElementType.DataPoint)
        {
            var prop = result.Object as DataPoint;
            if (prop != null)
            {
                var pointXPixel = result.ChartArea.AxisX.ValueToPixelPosition(prop.XValue);
                var pointYPixel = result.ChartArea.AxisY.ValueToPixelPosition(prop.YValues[0]);

                // check if the cursor is really close to the point (2 pixels around the point)
                if (Math.Abs(pos.X - pointXPixel) < 2 &&
                    Math.Abs(pos.Y - pointYPixel) < 2)
                {
                    tooltip.Show("X=" + prop.XValue + ", Y=" + prop.YValues[0], this.chart1,
                                    pos.X, pos.Y - 15);
                }
            }
        }
    }
}