feat: Upstream Doughnut Chart to RC

src/components/DoughnutChart/DoughnutChart.scss

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+@import "vanilla-framework";
+
+.doughnut-chart {
+  width: 6.5rem;
+
+  .doughnut-chart__tooltip {
+    display: block;
+  }
+
+  .doughnut-chart__tooltip > :only-child {
+    // Override the tooltip wrapper.
+    display: block !important;
+  }
+
+  .doughnut-chart__chart {
+    // Restrict hover areas to the strokes.
+    pointer-events: stroke;
+  }
+
+  .doughnut-chart__segment {
+    fill: transparent;
+
+    // Animate stroke size changes on hover.
+    transition: stroke-width 0.3s ease;
+  }
+}
+
+.doughnut-chart__legend {
+  list-style-type: none;
+}

src/components/DoughnutChart/DoughnutChart.stories.tsx

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+import { Meta, StoryObj } from "@storybook/react";
+
+import DoughnutChart from "./DoughnutChart";
+
+const meta: Meta<typeof DoughnutChart> = {
+  component: DoughnutChart,
+  tags: ["autodocs"],
+};
+
+export default meta;
+
+type Story = StoryObj<typeof DoughnutChart>;
+
+/**
+ * The Doughnut Chart component visually represents data segments in a circular format, with tooltips that appear on hover, and segments that can be customized via props.
+ */
+export const Default: Story = {
+  name: "Default",
+  args: {
+    chartID: "default",
+    segmentHoverWidth: 45,
+    segmentThickness: 40,
+    segments: [
+      {
+        color: "#0E8420",
+        tooltip: "Running",
+        value: 10,
+      },
+      {
+        color: "#CC7900",
+        tooltip: "Stopped",
+        value: 15,
+      },
+      { color: "#C7162B", tooltip: "Frozen", value: 5 },
+      { color: "#000", tooltip: "Error", value: 5 },
+    ],
+    size: 150,
+  },
+};

src/components/DoughnutChart/DoughnutChart.test.tsx

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+import { fireEvent, render, screen, waitFor } from "@testing-library/react";
+import React from "react";
+import DoughnutChart, { TestIds } from "./DoughnutChart";
+
+describe("DoughnutChart", () => {
+  const defaultProps = {
+    chartID: "test",
+    segmentHoverWidth: 10,
+    segmentThickness: 8,
+    size: 100,
+    segments: [
+      {
+        color: "#3498DB",
+        tooltip: "aaa",
+        value: 12,
+      },
+      {
+        color: "#E74C3C",
+        tooltip: "bbb",
+        value: 8,
+      },
+      {
+        color: "#F1C40F",
+        tooltip: "ccc",
+        value: 18,
+      },
+      {
+        color: "#2ECC71",
+        tooltip: "ddd",
+        value: 14,
+      },
+    ],
+  };
+
+  it("renders", () => {
+    render(<DoughnutChart {...defaultProps} />);
+    expect(screen.getByTestId("chart")).toBeInTheDocument();
+  });
+
+  it("displays the correct number of segments", () => {
+    render(<DoughnutChart {...defaultProps} />);
+    const segments = screen.getAllByTestId(TestIds.Segment);
+    expect(segments).toHaveLength(defaultProps.segments.length);
+  });
+
+  it("shows tooltips on hover", async () => {
+    const { container } = render(<DoughnutChart {...defaultProps} />);
+    const segments = screen.getAllByTestId(TestIds.Segment);
+
+    fireEvent.mouseOver(segments[0]);
+    fireEvent.click(container.firstChild.firstChild);
+
+    await waitFor(() => {
+      expect(screen.getByText("aaa")).toBeInTheDocument();
+    });
+  });
+
+  it("applies custom styles to segments", () => {
+    render(<DoughnutChart {...defaultProps} />);
+    const segment = screen.getAllByTestId(TestIds.Segment)[0];
+    expect(segment).toHaveStyle(`stroke: ${defaultProps.segments[0].color}`);
+    expect(segment).toHaveStyle(
+      `stroke-width: ${defaultProps.segmentThickness}`,
+    );
+  });
+
+  it("displays the label in the center if provided", () => {
+    render(<DoughnutChart {...defaultProps} label="Test Label" />);
+    expect(screen.getByTestId(TestIds.Label)).toHaveTextContent("Test Label");
+  });
+
+  it("does not display the label if not provided", () => {
+    render(<DoughnutChart {...defaultProps} />);
+    expect(screen.queryByText("Test Label")).not.toBeInTheDocument();
+  });
+});

src/components/DoughnutChart/DoughnutChart.tsx

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+import React, { FC, useRef, useState } from "react";
+import classNames from "classnames";
+import Tooltip from "components/Tooltip";
+import "./DoughnutChart.scss";
+
+export type Segment = {
+  /**
+   * The colour of the segment.
+   */
+  color: string;
+  /**
+   * The segment tooltip.
+   */
+  tooltip?: string;
+  /**
+   * The segment length.
+   */
+  value: number;
+};
+
+export type Props = {
+  /**
+   * The label in the centre of the doughnut.
+   */
+  label?: string;
+  /**
+   * An optional class name applied to the label.
+   */
+  labelClassname?: string;
+  /**
+   * An optional class name applied to the wrapping element.
+   */
+  className?: string;
+  /**
+   * The width of the segments when hovered.
+   */
+  segmentHoverWidth: number;
+  /**
+   * The width of the segments.
+   */
+  segmentThickness: number;
+  /**
+   * The doughnut segments.
+   */
+  segments: Segment[];
+  /**
+   * The size of the doughnut.
+   */
+  size: number;
+  /**
+   *  ID associated to the specific instance of a Chart.
+   */
+  chartID: string;
+};
+
+export enum TestIds {
+  Label = "label",
+  Segment = "segment",
+  Chart = "chart",
+  Section = "Section",
+}
+
+const DoughnutChart: FC<Props> = ({
+  className,
+  label,
+  labelClassname,
+  segmentHoverWidth,
+  segmentThickness,
+  segments,
+  size,
+  chartID,
+}): JSX.Element => {
+  const [tooltipMessage, setTooltipMessage] = useState<
+    Segment["tooltip"] | null
+  >(null);
+
+  const id = useRef(`doughnut-chart-${chartID}`);
+  const hoverIncrease = segmentHoverWidth - segmentThickness;
+  const adjustedHoverWidth = segmentHoverWidth + hoverIncrease;
+  // The canvas needs enough space so that the hover state does not get cut off.
+  const canvasSize = size + adjustedHoverWidth - segmentThickness;
+  const diameter = size - segmentThickness;
+  const radius = diameter / 2;
+  const circumference = Math.round(diameter * Math.PI);
+  // Calculate the total value of all segments.
+  const total = segments.reduce(
+    (totalValue, segment) => (totalValue += segment.value),
+    0,
+  );
+  let accumulatedLength = 0;
+  const segmentNodes = segments.map(({ color, tooltip, value }, i) => {
+    // The start position is the value of all previous segments.
+    const startPosition = accumulatedLength;
+    // The length of the segment (as a portion of the doughnut circumference)
+    const segmentLength = (value / total) * circumference;
+    // The space left until the end of the circle.
+    const remainingSpace = circumference - (segmentLength + startPosition);
+    // Add this segment length to the running tally.
+    accumulatedLength += segmentLength;
+
+    return (
+      <circle
+        className="doughnut-chart__segment"
+        cx={radius - segmentThickness / 2 - hoverIncrease}
+        cy={radius + segmentThickness / 2 + hoverIncrease}
+        data-testid={TestIds.Segment}
+        key={i}
+        tabIndex={0}
+        aria-label={tooltip ? `${tooltip}: ${value}` : `${value}`}
+        onMouseOut={
+          tooltip
+            ? () => {
+                // Hide the tooltip.
+                setTooltipMessage(null);
+              }
+            : undefined
+        }
+        onMouseOver={
+          tooltip
+            ? () => {
+                setTooltipMessage(tooltip);
+              }
+            : undefined
+        }
+        r={radius}
+        style={{
+          stroke: color,
+          strokeWidth: segmentThickness,
+          // The dash array used is:
+          // 1 - We want there to be a space before the first visible dash so
+          //     by setting this to 0 we can use the next dash for the space.
+          // 2 - This gap is the distance of all previous segments
+          //     so that the segment starts in the correct spot.
+          // 3 - A dash that is the length of the segment.
+          // 4 - A gap from the end of the segment to the start of the circle
+          //     so that the dash array doesn't repeat and be visible.
+          strokeDasharray: `0 ${startPosition.toFixed(
+            2,
+          )} ${segmentLength.toFixed(2)} ${remainingSpace.toFixed(2)}`,
+        }}
+        // Rotate the segment so that the segments start at the top of
+        // the chart.
+        transform={`rotate(-90 ${radius},${radius})`}
+      />
+    );
+  });
+
+  return (
+    <div
+      className={classNames("doughnut-chart", className)}
+      style={{ maxWidth: `${canvasSize}px` }}
+      data-testid={TestIds.Chart}
+    >
+      <Tooltip
+        className="doughnut-chart__tooltip"
+        followMouse={true}
+        message={tooltipMessage}
+        position="right"
+      >
+        <style>
+          {/* Set the hover width of the segments. */}
+          {`#${id.current} .doughnut-chart__segment:hover {
+          stroke-width: ${adjustedHoverWidth} !important;
+        }`}
+        </style>
+        <svg
+          className="doughnut-chart__chart"
+          id={id.current}
+          viewBox={`0 0 ${canvasSize} ${canvasSize}`}
+          data-testid={TestIds.Section}
+          aria-labelledby={`${id.current}-chart-title ${id.current}-chart-desc`}
+        >
+          {label && <title id={`${id.current}-chart-title`}>{label}</title>}
+          <desc id={`${id.current}-chart-desc`}>
+            {segments
+              .map((segment) => {
+                let description = "";
+                if (segment.tooltip) description += `${segment.tooltip}: `;
+                description += segment.value;
+                return description;
+              })
+              .join(",")}
+          </desc>
+
+          <mask id="canvasMask">
+            {/* Cover the canvas, this will be the visible area. */}
+            <rect
+              fill="white"
+              height={canvasSize}
+              width={canvasSize}
+              x="0"
+              y="0"
+            />
+            {/* Cut out the center circle so that the hover state doesn't grow inwards. */}
+            <circle
+              cx={canvasSize / 2}
+              cy={canvasSize / 2}
+              fill="black"
+              r={radius - segmentThickness / 2}
+            />
+          </mask>
+          <g mask="url(#canvasMask)">
+            {/* Force the group to cover the full size of the canvas, otherwise it will only mask the children (in their non-hovered state) */}
+            <rect
+              fill="transparent"
+              height={canvasSize}
+              width={canvasSize}
+              x="0"
+              y="0"
+            />
+            <g>{segmentNodes}</g>
+          </g>
+          {label ? (
+            <text
+              x={radius + adjustedHoverWidth / 2}
+              y={radius + adjustedHoverWidth / 2}
+            >
+              <tspan
+                className={classNames("doughnut-chart__label", labelClassname)}
+                data-testid={TestIds.Label}
+              >
+                {label}
+              </tspan>
+            </text>
+          ) : null}
+        </svg>
+      </Tooltip>
+    </div>
+  );
+};
+
+export default DoughnutChart;

src/components/DoughnutChart/index.ts

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+export { default } from "./DoughnutChart";
+export type { Props as DoughnutChartProps } from "./DoughnutChart";
+export type { Segment } from "./DoughnutChart";