🧠 polaris-viz-core

packages/polaris-viz-core contains platform agnostic utility functions, hooks, constants, types and UI components.

It gets published as the @shopify/polaris-viz-core library that is used by both @shopify/polaris-viz and @shopify/polaris-viz-native

👯‍♀️ Sharing code between React and React Native

Keeping the bundle size small

To keep the bundle size of the libraries small, @shopify/polaris-viz-core shouldn't depend on platform specific packages, like @react-native or @react-spring/web, directly.

Sharing UI components

To render SVG tags in React Native, we use the react-native-svg library. @shopify/polaris-viz doesn't need this package as a dependency though, since its targets are web browsers only. If we added react-native-svg as a depency of @shopify/polaris-viz-core we would also increase @shopify/polaris-viz bundle size for something that only @shopify/polaris-viz-native needs.

To solve this, we:

• Store all regular SVG tags as React components in the polaris-viz-context used by PolarisVizProvider:

// packages/polaris-viz-core/polaris-viz-context.ts

export const PolarisVizContext = createContext({
  components: {
    Svg: ({children, ...props}) => createElement('svg', props, children),
    Circle: ({children, ...props}) => createElement('circle', props, children),
    Ellipse: ({children, ...props}) => createElement('ellipse', props, children),
    G: ({children, ...props}) => createElement('g', props, children),
    Text: ({children, ...props}) => createElement('text', props, children),
    // ... other SVG tags
  },
});

• Re-export PolarisVizProvider from polaris-viz-native overwriting the regular SVG tags, with the equivalent tags from react-native-svg

// packages/polaris-viz-native/PolarisVizProvider.tsx

import {PolarisVizProvider as OriginalPolarisVizProvider} from '@shopify/polaris-viz-core';

import  {
  Svg,
  Circle,
  // ...
} from 'react-native-svg';

export const NativeComponents = {
  Svg,
  Circle,
  // ...
}

export const PolarisVizProvider = ({themes, children}) => {
  return (
    <OriginalPolarisVizProvider
      themes={themes}
      components={NativeComponents}
      animated={animated}
    >
      {children}
    </OriginalPolarisVizProvider>
  );
};

• When building UI components in polaris-viz-core, instead of using <svg> directly, we get <Svg> from the context:

// packages/polaris-viz-core/SomeSharedComponent.tsx

export function SomeSharedComponent() {
  const {
    components: {Svg, Rect},
  } = usePolarisVizContext();

  return (
    <Svg>
      <Rect />
    </Svg>
  )
}

With these changes in place,

• in polaris-viz: <Svg> and <Rect> will fetch the svg and rect tags from the default values of polaris-viz-context and render correctly in web browsers
• in polaris-viz-native: <Svg> and <Rect> will fetch the Svg and Rect tags from the react-native-svg library that were used to overwrite the default tags in the PolarisVizProvider, thus rendering correctly in React Native

To summarize:

We use react-spring to handle animations. This library also has platform specific exports to keep bundle size small: @react-spring/web and @react-spring/native

To animate components in core, we fetch the platform specific animated function from the PolarisVizContext, similarly to how we get the correct SVG tags.

// packages/polaris-viz-core/SomeSharedComponent.tsx

import { useSpring } from "@react-spring/core"

export function SomeSharedComponent() {
  const {
    components: {Svg, Circle},
    animated,
  } = usePolarisVizContext();

  const {animatedRadius} = useSpring({
    from: {
      animatedRadius: 0,
    },
    to: {
      animatedRadius: 100,
    },
  });

  const AnimatedCircle = animated(Circle);


  return (
    <Svg>
      <AnimatedCircle radius={animatedRadius} />
    </Svg>
  )
}