ysy00115 - 1 year ago 166
C# Question

How to pick up Mschart legend item on MouseClick?

When I click on an item in the legend,
I want to be output to Text (The legend of the items)
Click on the "Projected" Legend Items,
I want it to be put as "Projected" in the textbox.

Is there a way to do that?

Here is the crude calculation I mentioned in the comment:

First we use a function that converts the `Legend.Position` from percent to pixels:

``````RectangleF LegendClientRectangle(Chart chart, Legend L)
{
RectangleF LAR = L.Position.ToRectangleF();
float pw = chart.ClientSize.Width / 100f;
float ph = chart.ClientSize.Height / 100f;
return new RectangleF(pw * LAR.X, ph * LAR.Y, pw * LAR.Width, ph * LAR.Height);
}
``````

Next we code the `MouseClick` to get at the `Series` that belongs to the clicked position:

``````private void chart1_MouseClick(object sender, MouseEventArgs e)
{
Point mp = e.Location;
Legend L = chart1.Legends[0];
RectangleF LCR = LegendClientRectangle(chart1, L);

if ( LCR.Contains(mp) )
{
int yh = (int) (LCR.Height / chart1.Series.Count);
int myRel = (int)(mp.Y - LCR.Y);
int ser = myRel / yh;             // <--- this is the series index
Series S = chart1.Series[ser];    // add check here!
// decide which you have set and want to use..:
string text = S.LegendText != "" ?  S.LegendText : S.Name;
Console.WriteLine("Series # " + ser + " ->  " + text);
}
}
``````

Note that this code assumes that there is only one column of legenditems without extras like a Legend title.. If the layout has more columns or is a row-based layout you will have to adapt the code, which may not be so simple..

Also note that the text in a `LegendItem` may be set separately or be the default, i.e. the `Series.Name`. You should either know or test if the `LegendText` is set!

Update

I wonder why I didn't simply use `HitTest` for my answer:

``````private void chart1_MouseClick(object sender, MouseEventArgs e)
{
HitTestResult hit = chart1.HitTest(e.X, e.Y);
Series s = null;
if (hit != null) s = hit.Series;
if (s != null)
{
string text = s.LegendText != "" ?  s.LegendText : s.Name;
Console.WriteLine("Series # " + chart1.Series.IndexOf(s) + " ->  " + text);
}
}
``````
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