Asp.net + chart.customizelegend not having impact

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Hi everyone,

I was asked to put a number of graphics together for the office, and the "client" has a problem with the rectangles used within the chart's legend.

After doing some "research", I came across this MS document:
Chart.CustomizeLegend Event (System.Web.UI.DataVisualization.Charting)[^]

Which supposedly tells us how to "customize the chart legend items".

Despite my attempts, I cannot seem to affect said items at all.

What I have tried:

Markup:

<asp:Chart ID="PieChart" runat="server" Width="365px" OnCustomizeLegend="PieChart_CustomizeLegend">...

Code Behind:

protected void PieChart_CustomizeLegend(object sender, CustomizeLegendEventArgs e)
{
    foreach (LegendItem lgItem in e.LegendItems)
    {
        lgItem.MarkerStyle = MarkerStyle.Diamond;
    }
}

Would you happen to know what is it that I am missing?

Thanks for your input.

Posted 7-May-18 7:04am

alexvw

Updated 10-May-18 10:44am

v2

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alexvw · Accepted Answer · 2018-05-10T10:46:00

Hi there,

Please forgive me for not giving you all more time to come up with some ideas; here after, I'll explain what I did to get what I needed and leave all a question I was not able to find anything about.

All in all, customizing legend items was not as straight forward as I expected. I had to take the following steps:

1) Chart's legend has to be set to : LegendItemOrder="SameAsSeriesOrder", otherwise the result is all unorganized.

2) Modified the CustomizeLegend event as follows:

protected void PieChart_CustomizeLegend(object sender, CustomizeLegendEventArgs e)
        {
            foreach (LegendItem lgItem in e.LegendItems)
            {
                if (!string.IsNullOrEmpty(lgItem.Name))
                {
                    LegendItem cstItem = new LegendItem();
                    cstItem.ImageStyle = LegendImageStyle.Marker;
                    cstItem.MarkerColor = lgItem.Color;
                    cstItem.Name = lgItem.Name;
                    cstItem.MarkerStyle = MarkerStyle.Diamond;
                    cstItem.MarkerSize = 15;
                    ((Chart)sender).Legends[0].CustomItems.Add(cstItem);
                }
            }
           
            ((Chart)sender).Series[0].IsVisibleInLegend = false;

            ((Chart)sender).CustomizeLegend -= PieChart_CustomizeLegend;
        }

Note that set the series IsVisibleInLegend property inside the event and not in the markup. If done in there, nothing will be drawn in the legend.

Moreover, I noticed that, somehow I cannot explain, the CustomizeLegend event was begin fired three times, giving undesired results, thus the un-subscription.