@theme-ui/prism

A syntax highlighting component based on prism-react-renderer that works seamlessly with Theme UI.

Installation

npm i @theme-ui/prism

Usage

The syntax highlighting component needs to be passed to Theme UI context via the ThemeProvider.

// src/components/layout.js
import { ThemeUIProvider } from 'theme-ui'
import { MDXProvider } from '@mdx-js/react'
import { useThemedStylesWithMdx } from '@theme-ui/mdx'
import Prism from '@theme-ui/prism'

import theme from './theme'

const components = {
  pre: ({ children }) => <>{children}</>,
  code: Prism,
}

function Provider({ children }) {
  const componentsWithStyles = useThemedStylesWithMdx(
    useMDXComponents(components)
  )

  return (
    <ThemeProvider theme={theme}>
      <MDXProvider components={componentsWithStyles}>{children}</MDXProvider>
    </ThemeProvider>
  )
}

export default Provider

Then, all code blocks in MDX documents wrapped by Layout will be syntax highlighted.

Gatsby plugin

When using gatsby-plugin-theme-ui, shadow the src/gatsby-plugin-theme-ui/components.js module to add the Prism component to MDX scope.

// src/gatsby-plugin-theme-ui/components.js
import Prism from '@theme-ui/prism'

export default {
  pre: (props) => props.children,
  code: Prism,
}

Syntax themes

This package includes the default syntax color themes from the prismjs and prism-react-renderer packages. To add these to your Theme UI theme object, import a preset and add the styles to theme.styles.code.

// theme.js
import nightOwl from '@theme-ui/prism/presets/night-owl.json'

const theme = {
  // ...theme
  styles: {
    code: {
      ...nightOwl,
    },
  },
}

The following themes are available and can be found in the presets/ directory.

• dracula.json
• duotone-dark.json
• duotone-light.json
• github.json
• night-owl-light.json
• night-owl.json
• oceanic-next.json
• prism-coy.json
• prism-dark.json
• prism-funky.json
• prism-okaidia.json
• prism-solarizedlight.json
• prism-tomorrow.json
• prism-twilight.json
• prism.json
• shades-of-purple.json
• ultramin.json
• vs-dark.json

Theme UI colors

To theme the prism styles based on the colors defined in your theme.colors object, use the theme-ui preset, which will use the following color keys for syntax highlight.

• gray
• primary
• secondary
• accent

// src/gatsby-plugin-theme-ui/index.js
import prism from '@theme-ui/prism/presets/theme-ui'

export default {
  colors: {
    text: '#000',
    background: '#fff',
    primary: '#33e',
    secondary: '#119',
    accent: '#639',
    gray: '#666',
  },
  styles: {
    code: {
      ...prism,
    },
  },
}

Highlight support

This package supports highlighting inside code blocks. The following two syntaxes are supported:

Single-line highlight by placing // highlight-line at the end of the line.

let singleLineHighlight = 'there is a // highlight-line comment here ->' 

Multi-line highlights by wrapping lines with // highlight-start and // highlight-end. Multiple highlight wrappers are supported in a single code block.

let multiLineHighlight = `
  this multiline string is wrapped by 
  // highlight-start and // highlight-end 
  comments
`

The highlight styling is controlled in styles.pre under .highlight. For example:

".highlight": {
  "background": "hsla(0, 0%, 30%, .5)"
}

Additional languages

Please note that @theme-ui/prism uses prism-react-renderer, which does not include all languages supported in Prism by default. So, if you happen to use one of the missing languages, your code block simply won't show up as highlighted.

For example, to add support for the R language, import the language and pass a custom Prism instance to the Theme UI component:

// src/gatsby-plugin-theme-ui/components.js
import ThemeUIPrism from '@theme-ui/prism'
import PrismCore from 'prismjs/components/prism-core'
import 'prismjs/components/prism-r'

export default {
  pre: (props) => props.children,
  code: (props) => <ThemeUIPrism {...props} Prism={PrismCore} />,
}