DevExtreme v23.2 is now available.

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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.

Backend API
$(() => { const 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', }; $('#chart').dxChart({ dataSource, title: 'Noisy and Original Signals', commonSeriesSettings: { argumentField: 'argument', point: { visible: false, }, }, series: [{ valueField: 'originalValue', name: 'Original Signal', }, { valueField: 'value', name: 'Noisy Signal', }], legend: { verticalAlignment: 'bottom', horizontalAlignment: 'center', markerTemplate(item, group) { const marker = document.createElementNS('http://www.w3.org/2000/svg', 'path'); const background = document.createElementNS('http://www.w3.org/2000/svg', 'rect'); const color = item.series.isVisible() ? item.marker.fill : '#888'; background.setAttribute('fill', color); background.setAttribute('opacity', 0.3); background.setAttribute('width', 18); background.setAttribute('height', 18); background.setAttribute('x', 0); background.setAttribute('y', 0); marker.setAttribute('fill', color); marker.setAttribute('d', markerPath[item.series.name]); group.appendChild(marker); group.appendChild(background); }, }, onLegendClick(e) { if (e.target.isVisible()) { e.target.hide(); } else { e.target.show(); } }, }); });
<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>DevExtreme Demo</title> <meta http-equiv="X-UA-Compatible" content="IE=edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0" /> <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script> <script>window.jQuery || document.write(decodeURIComponent('%3Cscript src="js/jquery.min.js"%3E%3C/script%3E'))</script> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/23.2.5/css/dx.light.css" /> <script src="js/dx.all.js"></script> <script src="data.js"></script> <link rel="stylesheet" type="text/css" href="styles.css" /> <script src="index.js"></script> </head> <body class="dx-viewport"> <div class="demo-container"> <div id="chart"></div> </div> </body> </html>
#chart { height: 440px; }
function generateData(start, end, step) { const data = []; for (let i = start; i < end; i += step) { const originalValue = Math.sin(i) / i; data.push({ value: originalValue + ((0.5 - Math.random()) / 10), originalValue, argument: i }); } return data; } const dataSource = generateData(2.5, 12, 0.1);