Custom Components

Every element that a Victory component renders may be altered or completely replaced. Most components expose dataComponent, labelComponent, groupComponent, and containerComponent props. The primitive components that Victory components render by default are simple, stateless components with a consistent set of props whenever possible. These primitive components are exported for users to alter, wrap, extend and reference when creating custom components.

Altering default components

Victory components set props on their primitive components, but these may be overridden or augmented by setting props directly on the primitive component instances.

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  <VictoryBar
    data={[
      {x: 1, y: 3, label: "Alpha"},
      {x: 2, y: 4, label: "Bravo"},
      {x: 3, y: 6, label: "Charlie"},
      {x: 4, y: 3, label: "Delta"},
      {x: 5, y: 7, label: "Echo"},
    ]}
    labelComponent={
      <VictoryLabel angle={45} verticalAnchor="middle" textAnchor="end"/>
    }
    theme={VictoryTheme.clean}
  />

Wrapping components

Victory components may be wrapped to customize or change behavior. Wrapper components should apply any props they receive from other Victory components to the components they render.

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function WrapperComponent(props) {
  function renderChildren() {
    const children = React.Children.toArray(props.children);
    return children.map((child) => {
      // children should be rendered with props from their parent Victory components assigned
      // Components like `VictoryChart` expect to control props like `domain` for their children
      // Some props should be merged rather than overridden
      const style = _.merge(child.props.style, props.style);
      return React.cloneElement(child, Object.assign({}, child.props, props, { style }));
    });
  }

  return (
    <g transform="translate(20, 40)">
      <VictoryLabel text={"add labels"} x={110} y={30}/>
      <VictoryLabel text={"offset data from axes"} x={70} y={150}/>
      <VictoryLabel text={"alter props"} x={280} y={150}/>
      { renderChildren() }
    </g>
  );
}

function App() {
  return (
    <VictoryChart theme={VictoryTheme.clean}>
      <WrapperComponent>
        <VictoryScatter
          y={(d) => Math.sin(2 * Math.PI * d.x)}
          samples={15}
          symbol="square"
          size={6}
          style={{ data: { stroke: "lightblue", strokeWidth: 3 }}}
        />
      </WrapperComponent>
    </VictoryChart>
  );
}

render(<App/>);

Creating new components

Any component that renders valid svg elements (or elements wrapped in <foreignObject>) may be used as a dataComponent or labelComponent in Victory components. Custom components will be provided with the same props as default components. In the following example, a custom CatPoint component is used in place of Point in VictoryScatter.

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function CatPoint(props) {
  const {x, y, datum} = props;
  const cat = datum._y >= 0 ? "😻" : "😹";

  return (
    <text x={x} y={y} fontSize={30}>
      {cat}
    </text>
  );
}

function App() {
  return (
    <VictoryChart>
      <VictoryScatter
        y={(d) =>
          Math.sin(2 * Math.PI * d.x)
        }
        samples={25}
        dataComponent={<CatPoint/>}
      />
    </VictoryChart>
  );
}
render(<App/>);

More complex components may be supplied as direct children of VictoryChart. These components will have access to shared chart props such as scale. In the example below, the custom Polygon components draws a polygon based on a collection of points. The scale provided by VictoryChart is used to correctly position the points within the chart.

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const SAMPLE_DATA = [
	{x: 2, y: 1},
	{x: 3, y: 5},
	{x: 6, y: 3}
];

function getPoints(data, scale) {
  return data.reduce((pointStr, {x, y}) =>
    `${pointStr} ${scale.x(x)},${scale.y(y)}`
  , '');
}

function Polygon(props) {
  // data and style are explicitly supplied to the Polygon component
  // scale is provided by VictoryChart
  const { data, style, scale } = props;
  const points = getPoints(data, scale);
  return <polygon points={points} style={style}/>;
}

function App() {
  return (
    <VictoryChart domain={[-10, 10]} theme={VictoryTheme.clean}>
      <Polygon
        data={SAMPLE_DATA}
        style={{ fill: "lightblue", opacity: 0.5 }}
      />
      <VictoryScatter
        data={SAMPLE_DATA}
      />
    </VictoryChart>
  );
}

render(<App/>);

Other Victory components may even be used in creating custom components, as in the example below.

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function CustomPie(props) {
  const {datum, x, y} = props;
  const pieWidth = 120;

  return (
    <g transform={
      `translate(${x - pieWidth / 2}, ${y - pieWidth / 2})`
      }
    >
      <VictoryPie
        standalone={false}
        height={pieWidth}
        width={pieWidth}
        data={datum.pie}
        style={{labels: {fontSize: 0}}}
        colorScale={["#f77", "#55e", "#8af"]}
      />
    </g>
  );
}

function CustomDataComponent() {
  const data = [
    {x: "Jan", y: 30},
    {x: "Feb", y: 32},
    {x: "Mar", y: 65},
    {x: "Apr", y: 38},
    {x: "May", y: 50},
    {x: "Jun", y: 47},
    {x: "Jul", y: 38},
    {x: "Aug", y: 48},
    {x: "Sep", y: 80},
    {x: "Oct", y: 73},
    {x: "Nov", y: 76},
    {x: "Dec", y: 100}
  ];

  const pieData = data.map((datum) => {
    datum.pie = [
      {x: "Lions", y: Math.round(Math.random() * 10)},
      {x: "Tigers", y: Math.round(Math.random() * 10)},
      {x: "Bears", y: Math.round(Math.random() * 10)}
    ];
    return datum;
  });

  return (
    <VictoryChart domain={{y: [0, 100]}} theme={VictoryTheme.clean}>
      <VictoryAxis/>
      <VictoryGroup data={pieData}>
        <VictoryLine/>
        <VictoryScatter
          dataComponent={<CustomPie />}
        />
      </VictoryGroup>
    </VictoryChart>
  );
}

render(<CustomDataComponent/>);

Since any custom SVG element can be used as a Victory component, any styling system can be used to style custom components, including styled components, CSS modules, or inline styles.

Here's an example using SVG + styled components.

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const colors = ["#A8E6CE", "#DCEDC2", "#FFD3B5", "#FFAAA6", "#FF8C94"];

const ScatterPoint = ({ x, y, datum, min, max }) => {
  const i = React.useMemo(() => {
    return Math.floor(((datum.y - min) / (max - min)) * (colors.length - 1));
  }, [datum, min, max]);

  return <circle fill={colors[i]} cx={x} cy={y} r={6} />;
};

const App = () => {
  const data = [
    { x: "Jan", y: 43 },
    { x: "Feb", y: 44 },
    { x: "Mar", y: 47 },
    { x: "Apr", y: 51 },
    { x: "May", y: 57 },
    { x: "Jun", y: 62 },
    { x: "Jul", y: 67 },
    { x: "Aug", y: 68 },
    { x: "Sep", y: 63 },
    { x: "Oct", y: 54 },
    { x: "Nov", y: 47 },
    { x: "Dec", y: 42 }
  ];

  const temperatures = data.map(({ y }) => y);
  const min = Math.min(...temperatures);
  const max = Math.max(...temperatures);

  return (
    <VictoryChart theme={VictoryTheme.clean}>
      <VictoryLine data={data} />
      <VictoryScatter
        data={data}
        dataComponent={<ScatterPoint min={min} max={max} />}
      />
    </VictoryChart>
  );
}

render(<App/>);