Chart Elements and Hit-Testing

The FlexChart control is composed of elements that can be customized using its object model. The elements are:

  • PlotArea: The area within the axes.
  • ChartArea: The area within the control but outside the axes.
  • Legend: The chart legend, usually on the right of the plot area.
  • Header: The chart header, above the plot area.
  • Footer: The chart footer, below the plot area.
  • AxisX: The X-axis, usually horizontal.
  • AxisY: The Y-axis, usually vertical.
  • Series: A chart series.
  • SeriesSymbol: A symbol in a chart series.
  • DataLabel: A label attached to a data point.

You can use the hitTest method to determine what chart area is under the mouse.

Learn about FlexChart | Hit-Testing Documentation | FlexChart API Reference

import 'bootstrap.css'; import '@mescius/wijmo.styles/wijmo.css'; import './styles.css'; import { FlexChart, ChartElement, Palettes } from '@mescius/wijmo.chart'; import { isArray, format, Rect, Tooltip } from '@mescius/wijmo'; import { getData } from './data'; // document.readyState === 'complete' ? init() : window.onload = init; // function init() { // create a chart let theChart = new FlexChart('#theChart', { itemsSource: getData(), bindingX: 'country', chartType: 'LineSymbols', header: 'Header', footer: 'Footer', dataLabel: { content: '{value:n0}', position: 'Top', offset: 5 }, tooltip: { content: '' }, series: [ { binding: 'sales', name: 'Sales' }, { binding: 'expenses', name: 'Expenses' } ] }); theChart.palette = getRandomPalette(); // // use tooltip to show hit-test information let tt = new Tooltip(), tip = ''; // theChart.hostElement.addEventListener('mousemove', e => { // build tooltip text let ht = theChart.hitTest(e), elem = ht.chartElement, series = (ht.series && [1, 2, 3].indexOf(elem) < 0) ? ht.series : null, index = (ht.pointIndex != null && series) ? ht.pointIndex : null, newTip = format('chartElement: <b>{elem}</b><br/>series: <b>{series}</b><br/>pointIndex: <b>{index}</b>', { elem: ChartElement[elem], series: series ? series.name : 'none', index: index != null ? index : 'none' }); // // update tooltip if (newTip != tip) { tip = newTip; tt.show(e.target, tip, new Rect(e.clientX, e.clientY, 0, 0)); } }); // theChart.hostElement.addEventListener('mouseleave', e => { tt.hide(); tip = ''; }); } // function getRandomPalette() { let palettes = Object.keys(Palettes).filter(prop => isArray(Palettes[prop])); let rand = Math.floor(Math.random() * palettes.length); // return Palettes[palettes[rand]]; }
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <title>MESCIUS Wijmo FlexChart Chart Elements and Hit-Testing</title> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <!-- SystemJS --> <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.21.5/system.src.js" integrity="sha512-skZbMyvYdNoZfLmiGn5ii6KmklM82rYX2uWctBhzaXPxJgiv4XBwJnFGr5k8s+6tE1pcR1nuTKghozJHyzMcoA==" crossorigin="anonymous"></script> <script src="systemjs.config.js"></script> <script> System.import('./src/app'); </script> </head> <body> <div class="container-fluid"> <div id="theChart"></div> </div> </body> </html>
// create some random data export function getData() { let countries = 'US,Germany,UK,Japan,Italy,Greece'.split(','), data = []; // for (let i = 0; i < countries.length; i++) { data.push({ country: countries[i], sales: Math.random() * 10000, expenses: Math.random() * 5000, downloads: Math.round(Math.random() * 20000) }); } // return data; }
.wj-flexchart { height: 300px; } .wj-data-label { font-size: 75%; opacity: .9; } label { width: 150px; text-align: right; } .wj-control { margin-bottom: 3px; } body { margin-bottom: 24pt; }
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