feat(d3): Add text for center in donut charts

src/plugins/d3/__stories__/pie/Basic.stories.tsx

@@ -6,6 +6,7 @@ import {settings} from '../../../../libs';
 import {D3Plugin} from '../..';
 import {BasicPie} from '../../examples/pie/Basic';
 import {Donut} from '../../examples/pie/Donut';
+import {DonutWithTotals} from '../../examples/pie/DonutWithTotals';
 
 const ChartStory = ({Chart}: {Chart: React.FC}) => {
     const [shown, setShown] = React.useState(false);
@@ -41,6 +42,13 @@ export const BasicDonutStory: StoryObj<typeof ChartStory> = {
     },
 };
 
+export const DonutWithTotalsStory: StoryObj<typeof ChartStory> = {
+    name: 'Donut with totals',
+    args: {
+        Chart: DonutWithTotals,
+    },
+};
+
 export default {
     title: 'Plugins/D3/Pie',
     decorators: [withKnobs],

src/plugins/d3/examples/pie/DonutWithTotals.tsx

@@ -0,0 +1,44 @@
+import React from 'react';
+import {groups} from 'd3';
+import {ChartKit} from '../../../../components/ChartKit';
+import type {ChartKitWidgetData} from '../../../../types';
+import {ExampleWrapper} from '../ExampleWrapper';
+import nintendoGames from '../nintendoGames';
+import {CustomShapeRenderer} from '../../utils';
+
+function prepareData() {
+    const gamesByPlatform = groups(nintendoGames, (d) => d.esrb_rating || 'unknown');
+    return gamesByPlatform.map(([value, games]) => ({
+        name: value,
+        value: games.length,
+    }));
+}
+
+export const DonutWithTotals = () => {
+    const data = prepareData();
+    const totals = data.reduce((sum, d) => sum + d.value, 0);
+
+    const widgetData: ChartKitWidgetData = {
+        series: {
+            data: [
+                {
+                    type: 'pie',
+                    innerRadius: '50%',
+                    data: data,
+                    renderCustomShape: CustomShapeRenderer.pieCenterText(`${totals}`),
+                },
+            ],
+        },
+        legend: {enabled: true},
+        title: {
+            text: 'ESRB ratings',
+            style: {fontSize: '12px', fontWeight: 'normal'},
+        },
+    };
+
+    return (
+        <ExampleWrapper>
+            <ChartKit type="d3" data={widgetData} />
+        </ExampleWrapper>
+    );
+};

src/plugins/d3/index.ts

@@ -2,7 +2,7 @@ import React from 'react';
 import {ChartKitPlugin} from '../../types';
 
 export * from './types';
-
+export * from './utils';
 /**
  * It is an experemental plugin
  *

src/plugins/d3/renderer/hooks/useSeries/prepare-pie.ts

@@ -60,6 +60,7 @@ export function preparePieSeries(args: PreparePieSeriesArgs) {
                     },
                 },
             },
+            renderCustomShape: series.renderCustomShape,
         };
 
         return result;

src/plugins/d3/renderer/hooks/useSeries/types.ts

@@ -141,6 +141,7 @@ export type PreparedPieSeries = {
             halo: PreparedHaloOptions;
         };
     };
+    renderCustomShape?: PieSeries['renderCustomShape'];
 } & BasePreparedSeries;
 
 export type PreparedLineSeries = {

src/plugins/d3/renderer/hooks/useShapes/pie/index.tsx

@@ -55,6 +55,7 @@ export function PieSeriesShapes(args: PreparePieSeriesArgs) {
             .style('stroke', (pieData) => pieData.borderColor)
             .style('stroke-width', (pieData) => pieData.borderWidth);
 
+        // Render halo appearing outside the hovered slice
         shapesSelection
             .selectAll('halo')
             .data((pieData) => {
@@ -77,6 +78,7 @@ export function PieSeriesShapes(args: PreparePieSeriesArgs) {
             .attr('z-index', -1)
             .attr('visibility', getHaloVisibility);
 
+        // Render segments
         shapesSelection
             .selectAll(segmentSelector)
             .data((pieData) => pieData.segments)
@@ -128,6 +130,19 @@ export function PieSeriesShapes(args: PreparePieSeriesArgs) {
             .attr('stroke-linecap', 'round')
             .style('fill', 'none');
 
+        // Render custom shapes if defined
+        shapesSelection.each(function (d, index, nodes) {
+            const customShape = d.series.renderCustomShape?.({
+                series: {
+                    innerRadius: d.innerRadius,
+                },
+            });
+
+            if (customShape) {
+                (nodes[index] as Element).append(customShape as Node);
+            }
+        });
+
         const eventName = `hover-shape.pie`;
         const hoverOptions = get(seriesOptions, 'pie.states.hover');
         const inactiveOptions = get(seriesOptions, 'pie.states.inactive');

src/plugins/d3/utils/index.ts

@@ -0,0 +1,5 @@
+import {pieCenterText} from './pie-center-text';
+
+export const CustomShapeRenderer = {
+    pieCenterText,
+};

src/plugins/d3/utils/pie-center-text.ts

@@ -0,0 +1,31 @@
+import {create} from 'd3';
+import get from 'lodash/get';
+
+import {getLabelsSize} from '../renderer/utils';
+
+const MAX_FONT_SIZE = 64;
+
+export function pieCenterText(text: string, options?: {padding?: number}) {
+    if (!text) {
+        return undefined;
+    }
+
+    const padding = get(options, 'padding', 12);
+
+    return function (args: {series: {innerRadius: number}}) {
+        let fontSize = MAX_FONT_SIZE;
+
+        const textSize = getLabelsSize({labels: [text], style: {fontSize: `${fontSize}px`}});
+        fontSize = (fontSize * (args.series.innerRadius - padding) * 2) / textSize.maxWidth;
+
+        const container = create('svg:g');
+        container
+            .append('text')
+            .text(text)
+            .attr('text-anchor', 'middle')
+            .attr('alignment-baseline', 'middle')
+            .style('font-size', `${fontSize}px`);
+
+        return container.node();
+    };
+}

src/types/widget-data/pie.ts

@@ -1,3 +1,4 @@
+import {BaseType} from 'd3';
 import {SeriesType} from '../../constants';
 import type {BaseSeries, BaseSeriesData} from './base';
 import {ChartKitWidgetLegend, RectLegendSymbolOptions} from './legend';
@@ -74,4 +75,10 @@ export type PieSeries<T = any> = BaseSeries & {
          * */
         connectorCurve?: ConnectorCurve;
     };
+    /**
+     * Function for adding custom svg nodes for a series
+     *
+     * @return BaseType
+     * */
+    renderCustomShape?: (args: {series: {innerRadius: number}}) => BaseType;
 };