Pie.Chart (Component)
The Pie.Chart component is a child component of the PolarChart component and is responsible for rendering the Pie or Donut chart.
The example app inside this repo has a lot of examples of how to use the Pie.Chart and its associated components!
Example
The example below shows the most basic use of the Pie.Chart.
import { View } from "react-native";
import { Pie, PolarChart } from "victory-native";
function MyChart() {
return (
<View style={{ height: 300 }}>
<PolarChart
data={DATA} // 👈 specify your data
labelKey={"label"} // 👈 specify data key for labels
valueKey={"value"} // 👈 specify data key for values
colorKey={"color"} // 👈 specify data key for color
>
<Pie.Chart />
</PolarChart>
</View>
);
}
function randomNumber() {
return Math.floor(Math.random() * 26) + 125;
}
function generateRandomColor(): string {
// Generating a random number between 0 and 0xFFFFFF
const randomColor = Math.floor(Math.random() * 0xffffff);
// Converting the number to a hexadecimal string and padding with zeros
return `#${randomColor.toString(16).padStart(6, "0")}`;
}
const DATA = (numberPoints = 5) =>
Array.from({ length: numberPoints }, (_, index) => ({
value: randomNumber(),
color: generateRandomColor(),
label: `Label ${index + 1}`,
}));
Props
innerRadius
A number or string (as a percentage) which turns the Pie chart into a Donut chart. The innerRadius prop is the radius of the inner circle of the donut chart. If not provided, the chart will remain a Pie chart.
The innerRadius prop must be a number or a string like 50%.
circleSweepDegrees
A number which defines how many degrees of the chart should be drawn. The default is 360 which will draw a full circle. If you want to draw a partial circle, you can set this prop to a value between 0 and 360.
startAngle
A number which defines the starting angle of the chart. Changing this prop will rotate the chart.
size
A number which defines the size of the chart. This defaults to the canvas' width and height. This can be overriden with this prop (in case you want to position labels outside the chart, for example)
children
The children prop is a render function which maps through the data and whose sole argument is each individual slice of the pie, allowing you to customize each slice as needed. E.g. this slice will have all the data needed to render a Pie.Slice />.
If you do not provide any children, the Pie.Chart will just render a simple Pie.Slice /> for each slice.
However, you can provide children in order to add things like Pie.Label, Pie.SliceAngularInsets and LinearGradients amongst other things to each slice, or to wholly customize your own rendering.
See the Render Function Fields section for an outline of all of the available fields on the render function argument.
The example below shows a more complex use of the Pie.Chart:
Customizing Children Example
import { View } from "react-native";
import { Pie } from "victory-native";
function MyChart() {
return (
<View style={{ height: 300 }}>
<Pie.Chart
data={DATA} // 👈 specify your data
labelKey={"label"} // 👈 specify data key for labels
valueKey={"value"} // 👈 specify data key for values
colorKey={"color"} // 👈 specify data key for color
>
{/* 👇 each individual slice */}
{({ slice }) => {
const { startX, startY, endX, endY } = calculateGradientPoints(
slice.radius,
slice.startAngle,
slice.endAngle,
slice.center.x,
slice.center.y,
); // 👈 create your own custom fn to calculate the gradient details (see example app)
return (
<>
{/* 👇 return customized slice here */}
<Pie.Slice>
{/* 👇 configure slice label within Pie.Slice
<Pie.Label font={font} color={"white"} />
*/}
<LinearGradient
start={vec(startX, startY)}
end={vec(endX, endY)}
colors={[slice.color, `${slice.color}50`]}
positions={[0, 1]}
/>
</Pie.Slice>
<Pie.SliceAngularInset
angularInset={{
angularStrokeWidth: 5,
angularStrokeColor: "white",
}}
/>
</>
);
}}
</Pie.Chart>
</View>
);
}
function calculateGradientPoints(
radius: number,
startAngle: number,
endAngle: number,
centerX: number,
centerY: number,
) {
// Calculate the midpoint angle of the slice for a central gradient effect
const midAngle = (startAngle + endAngle) / 2;
// Convert angles from degrees to radians
const startRad = (Math.PI / 180) * startAngle;
const midRad = (Math.PI / 180) * midAngle;
// Calculate start point (inner edge near the pie's center)
const startX = centerX + radius * 0.5 * Math.cos(startRad);
const startY = centerY + radius * 0.5 * Math.sin(startRad);
// Calculate end point (outer edge of the slice)
const endX = centerX + radius * Math.cos(midRad);
const endY = centerY + radius * Math.sin(midRad);
return { startX, startY, endX, endY };
}
function randomNumber() {
return Math.floor(Math.random() * 26) + 125;
}
function generateRandomColor(): string {
// Generating a random number between 0 and 0xFFFFFF
const randomColor = Math.floor(Math.random() * 0xffffff);
// Converting the number to a hexadecimal string and padding with zeros
return `#${randomColor.toString(16).padStart(6, "0")}`;
}
const DATA = (numberPoints = 5) =>
Array.from({ length: numberPoints }, (_, index) => ({
value: randomNumber(),
color: generateRandomColor(),
label: `Label ${index + 1}`,
}));
Render Function Fields
The Pie.Chart children render function has a single argument that is an object with the following fields.
slice
An object of the form of PieSliceData which is the transformed data for each slice of the pie. The slice object has the following fields:
type PieSliceData = {
center: SkPoint;
color: Color;
endAngle: number;
innerRadius: number;
label: string;
radius: number;
sliceIsEntireCircle: boolean;
startAngle: number;
sweepAngle: number;
value: number;
};
Generally, you would not need to use the slice object directly, but it is available to you if you need to do something custom with each slice. Please refer to the example app repo for more information on how to use the slice object e.g the LinearGradient examples.
Pie Slice Labels
The <Pie.Slice /> accepts a <Pie.Label /> child element that allows for slice label customization.
The <Pie.Label /> accepts render props, and a custom render function.
font?: SkFont | null - Used for calculating the labels position and to be used with the Skia <Text /> element.
radiusOffset?: number - Used to move the slice label closer or further away from the pie chart center.
color?: Color - Set the labels color.
text?: String - Specify the text to use for the label. Defaults to slice.label.
children?: (position: LabelPosition) => ReactNode - Render function to allow custom slice labels. The <Pie.Label /> will do some calculations for you and pass the position based on radiusOffset you provide.
...
<>
<Pie.Slice>
{/* 👇 configure slice label with render props */}
<Pie.Label font={font} color={"white"} />
<LinearGradient
start={vec(startX, startY)}
end={vec(endX, endY)}
colors={[slice.color, `${slice.color}50`]}
positions={[0, 1]}
/>
</Pie.Slice>
</>
...
...
<>
<Pie.Slice>
{/* 👇 configure custom slice label with render function */}
<Pie.Label font={font} radiusOffset={0.5}>
{(position) => <CustomSliceLabel font={font} position={position} />}
</Pie.Label>
<LinearGradient
start={vec(startX, startY)}
end={vec(endX, endY)}
colors={[slice.color, `${slice.color}50`]}
positions={[0, 1]}
/>
</Pie.Slice>
</>
...
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