@carimus/react-native-theme-provider

A React Native package that wraps @callstack/react-theme-provider to add in some React Native-specific goodies.

See the react-theme-provider's docs for usage details.

Additions

withStyleSheet

When you call createTheming, the returned object will also contain a withStyleSheet property which creates a HOC when called with styles that injects a styleSheet into the component props.

In short this allows you to declare a component's stylesheet as a function of the theme, analogous to Material UI's withStyles.

Usage

withStyleSheet(styles, [options]) => ((YourComponent) => ThemedComponent)

Calling withStyleSheet returns a higher order component which you call with your component in order to inject a stylesheet based on the theme into your component.

Arguments

1. styles ((function(theme: object, props?: object): object) | object): If an object, styles is passed through StyleSheet.create() and given straight to the wrapped component as styleSheet. If it's a function, it will be called with the theme (and possibly the props as the second arg if options.withProps is set to true, not the default) and it should return an object which will be passed through StyleSheet.create() and given to the wrapped component as styleSheet.
2. options (object optional):
   • options.name (string; optional): Used when generating the display name of the wrapper component, otherwise YourComponent.displayName || YourComponent.name is used.
   • options.propName (string; optional, defaults to 'styleSheet'): The name of the prop to pass the generated and compiled stylesheet as to YourComponent
   • options.forwardTheme (boolean; optional, defaults to true): If true (the default), the theme will be passed into YourComponent on the theme prop.
   • options.withProps (boolean; optional, defaults to false): This has no effect if styles is an object. If true, the incoming props will be passed to your styles function as the second argument. Important note: this disables caching of the compiled stylesheet. The performance hit is marginal but if performance is crucial to this component, you should instead prefer to conditionally apply styles in your styleSheet in the render function of your component based on the props of interest, and, of course, appropriately implement shouldComponentUpdate or similar.
   • options.propagate (boolean; optional, defaults to true): If true (the default), will also wrap YourComponent in the ThemeProvider so that the final theme (i.e. including any merged in styles) will propagate into the subtree. This isn't strictly necessary if the theme is never modified and you have the ThemeProvider at the root of your app, but if you manually update the theme by providing a theme prop which will be merged into the contextual theme per the behaviour of withTheme, then you need to leave this as true in order for themed components in the subtree to use the same modified theme. If you don't want this (i.e. if you want components in the subtree to use the original theme), set this to false.

Notes

• The returned function is a HOC which you use to wrap your component. All props will be forwarded to your component with the addition of the styleSheet and theme props (both are configurable via options).
• theme is the original theme object that was passed to createTheming
• styleSheet is the result of StyleSheet.create() called on the styles object (or the result of calling styles if it's a function given the theme and optionally the props).
• If styles is a function and options.withProps is false, the result of calling styles with a given theme is cached. styles won't be called again to generate the styleSheet on future renders unless the theme changes.
• withStyleSheet implies withTheme so all behaviour that withTheme exhibits applies to withStyleSheet as well. For example, the component can be called with a theme prop and that theme will be merged into the contextual theme.

Example

theme.js

import { createTheming } from '@carimus/react-native-theme-provider';

const theme = {
    palette: {
        background: '#000000',
        foreground: '#FFFFFF',
    },
};

export const {
    ThemeProvider,
    withTheme,
    useTheme,
    withStyleSheet,
} = createTheming(theme);

FooComponent.js

import { View, Text } from 'react-native';

import { withStyleSheet } from './theme';

const styles = (theme) => ({
    root: {
        backgroundColor: theme.palette.background,
    },
    text: {
        color: theme.palette.foreground,
    },
});

function FooComponent({ styleSheet, children }) {
    return (
        <View style={styleSheet.root}>
            <Text style={styleSheet.text}>{children}</Text>
        </View>
    );
}

export default withStyleSheet(styles)(FooComponent);

TODO

• [ ] [withStyleSheet] Advanced caching in order to cache compiled styleSheets even when withProps is true.
• [ ] Some generic HOC that isn't dependent on a theme (i.e. isn't a result of createTheming) that can still somehow accept a theme dynamically from context and apply/merge it in to a default theme. For generic components to except a theme somehow but have sane defaults.