Getting Labels from Metadata
New to SciChart.js v3! DataLabels allow per data-point text labels to be drawn on series, or arbitrary text labels at x,y positions on the chart.
You can see several datalabel examples on the SciChart.js demo:
Explore these for some rich examples of how to use this API.
Formatting a DataLabel using metaDataSelector
Metadata allows you to assign optional javascript objects to individual x,y datapoints. To learn more about the Metadata API, see here.
DataLabels support rendering text from metadata as standard. You just need to provide a function to the metaDataSelector option that tells SciChart how to turn your metaData into text.
Find an example below:
This results in the following output:
<div id="scichart-root" ></div>
body { margin: 0; }
#scichart-root { width: 100%; height: 100vh; }
async function dataLabelsMetadata(divElementId) {
// #region ExampleA
const {
SciChartSurface,
NumericAxis,
FastLineRenderableSeries,
EllipsePointMarker,
XyDataSeries,
NumberRange,
SciChartJsNavyTheme
} = SciChart;
// or for npm: import { SciChartSurface, ... } from "scichart"
// Create a SciChartSurface with X,Y Axis
const { sciChartSurface, wasmContext } = await SciChartSurface.create(divElementId, {
theme: new SciChartJsNavyTheme()
});
sciChartSurface.xAxes.add(new NumericAxis(wasmContext, { growBy: new NumberRange(0.1, 0.1) }));
sciChartSurface.yAxes.add(new NumericAxis(wasmContext, { growBy: new NumberRange(0.1, 0.1) }));
// Create a chart with line series with a point-marker
// optional metadata is also passed with javascript objecst into the dataSeries
sciChartSurface.renderableSeries.add(new FastLineRenderableSeries(wasmContext, {
stroke: "SteelBlue",
strokeThickness: 3,
pointMarker: new EllipsePointMarker(wasmContext, {
width: 10,
height: 10,
strokeThickness: 2,
stroke: "SteelBlue",
fill: "LightSteelBlue"}),
dataSeries: new XyDataSeries(wasmContext, {
xValues: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12],
yValues: [4.3, 5.3, 6, 6.3, 6, 5.2, 4.5, 4.6, 5, 6, 7, 8],
metadata: [
{ text: "Bananas", isSelected: false },
{ text: "Apples", isSelected: false },
{ text: "Pears", isSelected: false },
{ text: "Pineapples", isSelected: false },
{ text: "Plums", isSelected: false },
{ text: "Cherries", isSelected: false },
{ text: "Strawberries", isSelected: false },
{ text: "Blueberries", isSelected: false },
{ text: "Lemons", isSelected: false },
{ text: "Limes", isSelected: false },
{ text: "Papaya", isSelected: false },
{ text: "Guava", isSelected: false },
]
}),
// Next, add the dataLabels. Simply setting dataLabel style makes labels visible
// We also pass a metaDataSelector which is a function that can be used to format labels from metadata objects
dataLabels: {
metaDataSelector: (metaData) => metaData.text,
style: {
fontFamily: "Arial",
fontSize: 16
},
color: "#EEE"
}
}));
// #endregion
}
dataLabelsMetadata('scichart-root')
async function builderExample(divElementId) {
// #region ExampleB
// Demonstrates how to add DataLabels to a chart with SciChart.js using the Builder API
const {
chartBuilder,
ESeriesType,
EThemeProviderType,
EPointMarkerType
} = SciChart;
// or, for npm, import { chartBuilder, ... } from "scichart"
const { wasmContext, sciChartSurface } = await chartBuilder.build2DChart(divElementId, {
surface: { theme: { type: EThemeProviderType.Dark } },
series: [
{
type: ESeriesType.LineSeries,
xyData: {
xValues: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12],
yValues: [4.3, 5.3, 6, 6.3, 6, 5.2, 4.5, 4.6, 5, 6, 7, 8],
metadata: [
{ text: "Bananas", isSelected: false },
{ text: "Apples", isSelected: false },
{ text: "Pears", isSelected: false },
{ text: "Pineapples", isSelected: false },
{ text: "Plums", isSelected: false },
{ text: "Cherries", isSelected: false },
{ text: "Strawberries", isSelected: false },
{ text: "Blueberries", isSelected: false },
{ text: "Lemons", isSelected: false },
{ text: "Limes", isSelected: false },
{ text: "Papaya", isSelected: false },
{ text: "Guava", isSelected: false },
]
},
options: {
stroke: "SteelBlue",
strokeThickness: 3,
pointMarker: {
type: EPointMarkerType.Ellipse,
options: {
width: 10,
height: 10,
strokeThickness: 2,
stroke: "SteelBlue",
fill: "LightSteelBlue"
}
},
// Next, add the dataLabels. Simply setting dataLabel style makes labels visible
// We also pass a metaDataSelector which is a function that can be used to format labels from metadata objects
dataLabels: {
metaDataSelector: (metaData) => metaData.text,
style: {
fontFamily: "Arial",
fontSize: 16
},
color: "#EEE"
}
}
}
]
});
// #endregion
};
// Uncomment this to use the builder example
//builderExample("scichart-root");
Accessing Metadata from getText() and DataLabelState
The metaDataSelector option allows you to return values stored in the metadata of a dataSeries, but what if you wanted to have more complex formatting mixing index, x, y value or the metadata values?
You can also access metadata via a custom DataLabelProvider.getText() function. This technique is covered in the article Custom DataLabel Formatting.
Once you've setup a custom formatting function, you can then use dataLabelState.getMetaData() to get the metaData for the current point.
Here's an example:
This results in the following output.
<div id="scichart-root" ></div>
body { margin: 0; }
#scichart-root { width: 100%; height: 100vh; }
async function dataLabelsMetadataFromGetText(divElementId) {
const {
SciChartSurface,
NumericAxis,
FastLineRenderableSeries,
EllipsePointMarker,
XyDataSeries,
NumberRange,
SciChartJsNavyTheme,
EDataLabelSkipMode
} = SciChart;
// or for npm: import { SciChartSurface, ... } from "scichart"
// Create a SciChartSurface with X,Y Axis
const { sciChartSurface, wasmContext } = await SciChartSurface.create(divElementId, {
theme: new SciChartJsNavyTheme()
});
sciChartSurface.xAxes.add(new NumericAxis(wasmContext, { growBy: new NumberRange(0.2, 0.2) }));
sciChartSurface.yAxes.add(new NumericAxis(wasmContext, { growBy: new NumberRange(0.1, 0.2) }));
// Create a chart with line series with a point-marker
// optional metadata is also passed with javascript objecst into the dataSeries
sciChartSurface.renderableSeries.add(new FastLineRenderableSeries(wasmContext, {
stroke: "SteelBlue",
strokeThickness: 3,
pointMarker: new EllipsePointMarker(wasmContext, {
width: 10,
height: 10,
strokeThickness: 2,
stroke: "SteelBlue",
fill: "LightSteelBlue"}),
dataSeries: new XyDataSeries(wasmContext, {
xValues: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12],
yValues: [4.3, 5.3, 6, 6.3, 6, 5.2, 4.5, 4.6, 5, 6, 7, 8],
metadata: [
{ text: "Bananas", isSelected: false },
{ text: "Apples", isSelected: false },
{ text: "Pears", isSelected: false },
{ text: "Pineapples", isSelected: false },
{ text: "Plums", isSelected: false },
{ text: "Cherries", isSelected: false },
{ text: "Strawberries", isSelected: false },
{ text: "Blueberries", isSelected: false },
{ text: "Lemons", isSelected: false },
{ text: "Limes", isSelected: false },
{ text: "Papaya", isSelected: false },
{ text: "Guava", isSelected: false },
]
}),
// Next, add the dataLabels. Simply setting dataLabel style makes labels visible
dataLabels: {
style: {
fontFamily: "Arial",
fontSize: 13
},
skipMode: EDataLabelSkipMode.ShowAll,
color: "#EEE"
}
}));
// #region ExampleA
// Assuming metadata has been constructed in the dataseries and dataLabels enabled,
// you can format labels with metadata using dataLabelProvider.getText(dataLabelState)
sciChartSurface.renderableSeries.get(0).dataLabelProvider.getText = (dataLabelState) => {
return `index=${dataLabelState.index},
x,y=[${dataLabelState.xVal()}, ${dataLabelState.yVal()}],
metadata="${dataLabelState.getMetaData()?.text}"`;
};
// #endregion
}
dataLabelsMetadataFromGetText('scichart-root')