Zoom and Pan a Realtime JavaScript Chart

1import {
2    EExecuteOn,
3    EllipsePointMarker,
4    EZoomState,
5    FastLineRenderableSeries,
6    NumberRange,
7    NumericAxis,
8    RubberBandXyZoomModifier,
9    SciChartSurface,
10    XyDataSeries,
11    XyScatterRenderableSeries,
12    ZoomExtentsModifier,
13    ZoomPanModifier,
14} from "scichart";
15
16import { appTheme } from "../../../theme";
17
18export const drawExample = async (rootElement: string | HTMLDivElement) => {
19    // Create the SciChartSurface in the div 'scichart-root'
20    // The SciChartSurface, and webassembly context 'wasmContext' are paired. This wasmContext
21    // instance must be passed to other types that exist on the same surface.
22    const { sciChartSurface, wasmContext } = await SciChartSurface.create(rootElement, {
23        theme: appTheme.SciChartJsTheme,
24    });
25
26    // Create an X,Y Axis and add to the chart
27    const xAxis = new NumericAxis(wasmContext, { labelPrecision: 0 });
28    const yAxis = new NumericAxis(wasmContext);
29
30    sciChartSurface.xAxes.add(xAxis);
31    sciChartSurface.yAxes.add(yAxis);
32
33    // Create a Scatter series, and Line series and add to chart
34    const scatterSeries = new XyScatterRenderableSeries(wasmContext, {
35        pointMarker: new EllipsePointMarker(wasmContext, { width: 7, height: 7, fill: "White", stroke: "SteelBlue" }),
36    });
37    const lineSeries = new FastLineRenderableSeries(wasmContext, { stroke: "#4083B7", strokeThickness: 2 });
38    sciChartSurface.renderableSeries.add(lineSeries, scatterSeries);
39
40    const initialDataPointsCount = 1000;
41
42    // if a required size of data series is known or it is expected to grow,
43    // setting a capacity value may give some efficiency boost
44    const initialCapacity = 2000;
45
46    // Create and populate some XyDataSeries with static data
47    // Note: you can pass xValues, yValues arrays to constructors, and you can use appendRange for bigger datasets
48    const scatterData = new XyDataSeries(wasmContext, { dataSeriesName: "Cos(x)", capacity: initialCapacity });
49    const lineData = new XyDataSeries(wasmContext, { dataSeriesName: "Sin(x)", capacity: initialCapacity });
50
51    for (let i = 0; i < initialDataPointsCount; i++) {
52        lineData.append(i, Math.sin(i * 0.05));
53        scatterData.append(i, Math.cos(i * 0.05));
54    }
55
56    // Assign these dataseries to the line/scatter renderableseries
57    scatterSeries.dataSeries = scatterData;
58    lineSeries.dataSeries = lineData;
59
60    //  We disable ZoomExtends animation
61    sciChartSurface.chartModifiers.add(new ZoomExtentsModifier({ isAnimated: false }));
62    // Realtime zooming example
63    sciChartSurface.chartModifiers.add(new RubberBandXyZoomModifier());
64    // Realtime panning example
65    sciChartSurface.chartModifiers.add(
66        new ZoomPanModifier({ executeCondition: { button: EExecuteOn.MouseRightButton } })
67    );
68
69    // Part 2: Appending data in realtime
70    //
71    let timerId: NodeJS.Timeout;
72
73    const updateDataFunc = () => {
74        // Append another data-point to the chart. We use dataSeries.count()
75        // to determine the current length before appending
76        // NOTE: sometimes appending data points in bulk with appendRange can be more efficient
77        const i = lineData.count();
78        lineData.append(i, Math.sin(i * 0.05));
79        scatterData.append(i, Math.cos(i * 0.05));
80
81        // If the zoomState is not UserZooming, then we are viewing the extents of the data
82        // In this case, we want to scroll the chart by setting visibleRange = NumberRange(i-1000, i)
83        if (sciChartSurface.zoomState !== EZoomState.UserZooming) {
84            xAxis.visibleRange = new NumberRange(i - 1000, i);
85        }
86    };
87
88    const startUpdate = () => {
89        // Repeat at 60Hz
90        timerId = setInterval(updateDataFunc, 16);
91        // Warning, this will repeat forever, it's not best practice!
92    };
93
94    const stopUpdate = () => {
95        clearTimeout(timerId);
96    };
97
98    return { sciChartSurface, controls: { startUpdate, stopUpdate } };
99};
100