@react-native-vector-icons/common/src/dynamicLoading/dynamic-loading-setting.ts

Customizable Icons for React Native with support for image source and full styling.

import type { FontSource } from './types';

declare global {
  interface ExpoGlobal {
    modules: {
      ExpoAsset: {
        // definition from
        // https://github.com/expo/expo/blob/1f5a5991d14aad09282d1ce1612b44d30e7e7d3d/packages/expo-asset/ios/AssetModule.swift#L23
        downloadAsync: (uri: string, hash: string | undefined, type: string) => Promise<string>;
      };
      ExpoFontLoader: {
        // definition from
        // https://github.com/expo/expo/blob/1f5a5991d14aad09282d1ce1612b44d30e7e7d3d/packages/expo-font/ios/FontLoaderModule.swift#L18
        getLoadedFonts: () => string[];
        loadAsync: (fontFamilyAlias: string, fileUri: string) => Promise<void>;
      };
    };
  }

  // eslint-disable-next-line vars-on-top
  var expo: ExpoGlobal | undefined;
}

const hasNecessaryExpoModules = !!globalThis.expo?.modules?.ExpoAsset && !!globalThis.expo?.modules?.ExpoFontLoader;

const hasNecessaryExpoFeatures =
  hasNecessaryExpoModules && typeof globalThis.expo?.modules.ExpoFontLoader.getLoadedFonts === 'function';

let dynamicFontLoadingEnabled = hasNecessaryExpoFeatures;

export const isDynamicLoadingSupported = () => hasNecessaryExpoFeatures;

/**
 * Set whether dynamic loading of fonts is enabled.
 * Currently, the presence of Expo Asset and Font Loader modules is a prerequisite for enabling.
 * In the future, React Native core apis will be used for dynamic font loading.
 *
 * @param value - whether dynamic loading of fonts is enabled
 * @returns `true` if dynamic loading of fonts was successfully set. `false` otherwise.
 * */
export const setDynamicLoadingEnabled = (value: boolean): boolean => {
  if (!hasNecessaryExpoFeatures) {
    if (process.env.NODE_ENV !== 'production' && !!value) {
      const message = hasNecessaryExpoModules
        ? 'Expo is installed, but does not support dynamic font loading. Make sure to use Expo SDK 52 or newer.'
        : 'Necessary Expo modules not found. Dynamic font loading is not available on Web or when necessary Expo modules are not present.';
      console.error(message); // eslint-disable-line no-console
    }
    return false;
  }

  dynamicFontLoadingEnabled = !!value;

  return true;
};

/**
 * Whether dynamic loading of fonts is enabled.
 * */
export const isDynamicLoadingEnabled = () => dynamicFontLoadingEnabled;

type ErrorCallback = (args: {
  error: Error;
  fontFamily: string;
  fontSource: FontSource;
}) => void;

let dynamicLoadingErrorCallback: undefined | ErrorCallback;

/**
 * Set a callback to be called when an error occurs during dynamic font loading.
 * */
export const setDynamicLoadingErrorCallback = (callback: ErrorCallback) => {
  dynamicLoadingErrorCallback = callback;
};

export const getErrorCallback = () => dynamicLoadingErrorCallback;