Charts - Custom Legend Markers

Legend markers are SVG elements. To customize a legend marker, declare the SVG markup in the markerTemplate. You can access the legend item data object inside the template and use it to identify the series and read its parameters.

In this demo, the markers' appearance changes when you click the markers to show or hide the corresponding series.

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Backend API

@(Html.DevExtreme().Chart() .ID("chart") .CommonSeriesSettings(s => s .ArgumentField("Argument") .Point(p => p.Visible(false)) ) .Title(t => t.Text("Noisy and Original Signals")) .Series(s => { s.Add().ValueField("OriginalValue").Name("Original Signal"); s.Add().ValueField("Value").Name("Noisy Signal"); }) .OnLegendClick( @<text> function(e){ e.target.isVisible()?e.target.hide():e.target.show(); } </text>) .Legend(l => l .VerticalAlignment(VerticalEdge.Bottom) .HorizontalAlignment(HorizontalAlignment.Center) .MarkerTemplate( @<text> <% var color = series.isVisible() ? marker.fill : "#888" %> <svg> <rect x="0" y="0" width="18px" height="18px" fill="<%- color %>" opacity="0.3"></rect> <path d="<%- getMarkerPath(series.name)%>" fill="<%- color %>"></path> </svg> </text>)) .DataSource(Model) ) <script> var markerPath = { "Original Signal": "M 0 8 C 2 4 7 4 9.5 8 C 11 12 16 12 18 8 L 18 10 C 16 14 11 14 8.5 10 C 7 6 2 6 0 10 Z", "Noisy Signal": "M 18 8 L 12 12 L 7 3 L 0 7.4 L 0 10 L 6 6 L 11 15 L 18 10.6 Z" }; function getMarkerPath(seriesName) { return markerPath[seriesName]; } </script>

using DevExtreme.AspNet.Data; using DevExtreme.AspNet.Mvc; using DevExtreme.MVC.Demos.Models.SampleData; using System; using System.Collections.Generic; using System.Linq; using System.Text.Json; using System.Web.Mvc; namespace DevExtreme.MVC.Demos.Controllers { public class ChartsController : Controller { public ActionResult CustomLegendMarkers() { return View(SampleData.GetCustomLegendMarkersSampleData()); } } }

using System; using System.Collections.Generic; using System.Linq; using DevExpress.Data.Utils; namespace DevExtreme.MVC.Demos.Models.SampleData { public partial class SampleData { public static IEnumerable<object> GetCustomLegendMarkersSampleData() { var random = NonCryptographicRandom.System; return Enumerable.Range(25, 120).Select(x => { var argument = (Double)x / 10; var originalValue = Math.Sin(argument) / argument; return new { Argument = argument, OriginalValue = originalValue, Value = originalValue + (0.5 - random.NextDouble()) / 10 }; }); } } }

#chart { height: 440px; }