Drawing PointMarkers on Series (Scatter markers)
Every data point of a Scatter, Line, Bubble, Mountain, Spline, Error or Column Series may be marked with a PointMarker. So, not just limited to scatter series, you can apply a pointmarker to line series, or error bars to display a repeated marker at the X,Y point.
Simply set BaseRenderableSeries.pointMarker = new EllipsePointMarker() to apply a scatter point to most series types.
Several different types of PointMarker are available in SciChart.js:
- EllipsePointMarker - Renders a circle at each point
- SquarePointMarker - Renders a square at each point
- TrianglePointMarker - Renders a triangle at each point
- CrossPointMarker - Renders a plus sign '+' at each point
- XPointMarker - Renders an 'x' at each point
- SpritePointMarker - Allows an image to be used at each point to create custom pointmarkers
Below we're going to show some options how to use different types of PointMarker in SciChart.
This results in the following output:
<div id="scichart-root" ></div>
body { margin: 0; }
#scichart-root { width: 100%; height: 100vh; }
async function createScatterChartWithManyPointMarkers(divElementId) {
// Demonstrates how to create a line chart with pointmarkers using SciChart.js
const {
SciChartSurface,
NumericAxis,
NumberRange,
XyDataSeries,
XyScatterRenderableSeries,
EllipsePointMarker,
SquarePointMarker,
CrossPointMarker,
SpritePointMarker,
TrianglePointMarker,
SciChartJsNavyTheme,
createImageAsync
} = SciChart;
// or, for npm, import { SciChartSurface, ... } from "scichart"
const createData = (wasmContext) => {
// Create some dataseries
const xValues = [];
const yValues1 = [];
const yValues2 = [];
const yValues3 = [];
const yValues4 = [];
const yValues5 = [];
// Append values
const dataSize = 30;
for (let i = 0; i < dataSize; i++) {
xValues.push(i);
yValues1.push(Math.random() + 0.5);
yValues2.push(Math.random() + 2);
yValues3.push(Math.random() + 4);
yValues4.push(Math.random() + 6);
yValues5.push(Math.random() + 8);
}
return { xValues, yValues1, yValues2, yValues3, yValues4, yValues5 };
};
// #region ExampleA
// Create a chart with X,Y axis
const { sciChartSurface, wasmContext } = await SciChartSurface.create(divElementId, {
theme: new SciChartJsNavyTheme()
});
sciChartSurface.xAxes.add(new NumericAxis(wasmContext));
sciChartSurface.yAxes.add(new NumericAxis(wasmContext, { growBy: new NumberRange(0.0, 0.4) }));
// Create some data
const { xValues, yValues1, yValues2, yValues3, yValues4, yValues5 } = createData();
const commonOptions = { width: 11, height: 11, strokeThickness: 2 };
// Add a line series with EllipsePointMarker
sciChartSurface.renderableSeries.add(
new XyScatterRenderableSeries(wasmContext, {
pointMarker: new EllipsePointMarker(wasmContext, {
...commonOptions,
fill: "#0077FF99",
stroke: "LightSteelBlue"
}),
dataSeries: new XyDataSeries(wasmContext, { xValues, yValues: yValues1 })
})
);
// Add a scatter series with SquarePointMarker
sciChartSurface.renderableSeries.add(
new XyScatterRenderableSeries(wasmContext, {
pointMarker: new SquarePointMarker(wasmContext, {
...commonOptions,
fill: "#FF000099",
stroke: "Red"
}),
dataSeries: new XyDataSeries(wasmContext, { xValues, yValues: yValues2 })
})
);
// Add a scatter series with TrianglePointMarker
sciChartSurface.renderableSeries.add(
new XyScatterRenderableSeries(wasmContext, {
pointMarker: new TrianglePointMarker(wasmContext, {
...commonOptions,
fill: "#FFDD00",
stroke: "#FF6600"
}),
dataSeries: new XyDataSeries(wasmContext, { xValues, yValues: yValues3 })
})
);
// Add a scatter series with CrossPointMarker
sciChartSurface.renderableSeries.add(
new XyScatterRenderableSeries(wasmContext, {
pointMarker: new CrossPointMarker(wasmContext, {
...commonOptions,
stroke: "#FF00FF"
}),
dataSeries: new XyDataSeries(wasmContext, { xValues, yValues: yValues4 })
})
);
// Add a scatter series with Custom Image using SpritePointMarker
const imageBitmap = await createImageAsync("https://demo.scichart.com/images/CustomMarkerImage.png");
sciChartSurface.renderableSeries.add(
new XyScatterRenderableSeries(wasmContext, {
pointMarker: new SpritePointMarker(wasmContext, {
image: imageBitmap
}),
dataSeries: new XyDataSeries(wasmContext, { xValues, yValues: yValues5 })
})
);
// #endregion
};
createScatterChartWithManyPointMarkers("scichart-root");
// Demonstrates the alternative Builder-API to create a line chart with gaps
async function builderExample(divElementId) {
const {
chartBuilder,
NumberRange,
EAxisType,
ESeriesType,
EPointMarkerType,
EThemeProviderType,
createImageAsync
} = SciChart;
// or, for npm, import { SciChartSurface, ... } from "scichart"
const createData = (wasmContext) => {
// Create some dataseries
const xValues = [];
const yValues1 = [];
const yValues2 = [];
const yValues3 = [];
const yValues4 = [];
const yValues5 = [];
// Append values
const dataSize = 30;
for (let i = 0; i < dataSize; i++) {
xValues.push(i);
yValues1.push(Math.random() + 0.5);
yValues2.push(Math.random() + 2);
yValues3.push(Math.random() + 4);
yValues4.push(Math.random() + 6);
yValues5.push(Math.random() + 8);
}
return { xValues, yValues1, yValues2, yValues3, yValues4, yValues5 };
};
const { xValues, yValues1, yValues2, yValues3, yValues4, yValues5 } = createData();
// #region ExampleB
const { wasmContext, sciChartSurface } = await chartBuilder.build2DChart(divElementId, {
surface: { theme: { type: EThemeProviderType.Dark } },
xAxes: { type: EAxisType.NumericAxis },
yAxes: { type: EAxisType.NumericAxis, options: { growBy: new NumberRange(0, 0.15) }},
series: [
{
type: ESeriesType.ScatterSeries,
xyData: {
xValues,
yValues: yValues1
},
options: {
pointMarker: {
type: EPointMarkerType.Ellipse,
options: {
width: 11,
height: 11,
strokeThickness: 2,
fill: "#0077FF99",
stroke: "LightSteelBlue"
}
}
}
},
{
type: ESeriesType.ScatterSeries,
xyData: {
xValues,
yValues: yValues2
},
options: {
pointMarker: {
type: EPointMarkerType.Square,
options: {
width: 11,
height: 11,
strokeThickness: 2,
fill: "#FF000099",
stroke: "Red"
}
}
}
},
{
type: ESeriesType.ScatterSeries,
xyData: {
xValues,
yValues: yValues3,
},
options: {
pointMarker: {
type: EPointMarkerType.Triangle,
options: {
width: 11,
height: 11,
strokeThickness: 2,
fill: "#FFDD00",
stroke: "#FF6600"
}
}
}
},
{
type: ESeriesType.ScatterSeries,
xyData: {
xValues,
yValues: yValues4
},
options: {
pointMarker: {
type: EPointMarkerType.Cross,
options: {
width: 11,
height: 11,
strokeThickness: 2,
stroke: "#FF00FF"
}
}
}
},
{
type: ESeriesType.ScatterSeries,
xyData: {
xValues,
yValues: yValues5
},
options: {
pointMarker: {
type: EPointMarkerType.Sprite,
options: {
image: await createImageAsync("https://demo.scichart.com/images/CustomMarkerImage.png")
}
}
}
}
]
});
// #endregion
};
// Uncomment this to use the builder example
//builderExample("scichart-root");
IsLastPointOnly mode for Pointmarkers
New to SciChart.js v3.2! The PointMarker type has a property isLastPointOnly. When true, only the last point of a scatter series is drawn. This can be useful to highlight a point in say a sweeping ECG chart.
Additional Tips for PointMarkers
Custom markers can be created using the SpritePointMarker type, which allows loading a custom image as a marker. This uses the helper function createImageAsync which allows loading of a PNG file either from URL, or locally hosted / imported image.
For a TypeScript / npm & webpack example you can see the JavaScript Custom PointMarkers Chart example in the SciChart.js demo.