Viewer: Internationalization

OHIF supports internationalization using i18next through the npm package @ohif/i18n, where is the main instance of i18n containing several languages and tools.

Our translation management is powered by Locize through their generous support of open source.

Installing

yarn add @ohif/i18n

# OR

npm install --save @ohif/i18n

How it works

After installing @ohif/i18n npm package, the translation function t can be used with or without React.

A translation will occur every time a text match happens in a t function.

The t function is responsible for getting translations using all the power of i18next.

E.g.

Before:

<div>my translated text</div>

After:

<div>{t('my translated text')}</div>

If the translation.json file contains a key that matches the HTML content e.g. my translated text, it will be replaced automatically by the t function.

---

With React

This section will introduce you to react-i18next basics and show how to implement the t function easily.

Using HOCs

In most cases we used High Order Components to share the t function among OHIF's components.

E.g.

import React from 'react';
import { withTranslation } from '@ohif/i18n';

function MyComponent({ t, i18n }) {
  return <p>{t('my translated text')}</p>;
}

export default withTranslation('MyNameSpace')(MyComponent);

Important: if you are using React outside the OHIF Viewer, check the I18nextProvider section, withTranslation HOC doesnt works without a I18nextProvider

Using Hooks

Also, it's possible to get the t tool using React Hooks, but it requires at least React > 16.8 😉

Using outside of OHIF viewer

OHIF Viewer already sets a main I18nextProvider connected to the shared i18n instance from @ohif/i18n, all extensions inside OHIF Viewer will share this same provider at the end, you don't need to set new providers at all.

But, if you need to use it completely outside of OHIF viewer, you can set the I18nextProvider this way:

import i18n from '@ohif/i18n';
import { I18nextProvider } from 'react-i18next';
import App from './App';

<I18nextProvider i18n={i18n}>
  <App />
</I18nextProvider>;

After setting I18nextProvider in your React App, all translations from @ohif/i18n should be available following the basic With React usage.

---

Without React

When needed, you can also use available translations without React.

E.g.

import { T } from '@ohif/i18n';
console.log(T('my translated text'));
console.log(T('$t(Common:Play) my translated text'));

---

Main Concepts While Translating

Namespaces

Namespaces are being used to organize translations in smaller portions, combined semantically or by use. Each .json file inside @ohif/i18n npm package becomes a new namespace automatically.

• Buttons: All buttons translations
• CineDialog: Translations for the toll tips inside the Cine Player Dialog
• Common: all common jargons that can be reused like t('$t(common:image)')
• Header: translations related to OHIF's Header Top Bar
• MeasurementTable - Translations for the @ohif/ui Measurement Table
• UserPreferencesModal - Translations for the @ohif/ui Preferences Modal

How to use another NameSpace inside the current NameSpace?

i18next provides a parsing feature able to get translations strings from any NameSpace, like this following example getting data from Common NameSpace:

$t(Common:Reset)

Extending Languages in @ohif/i18n

Sometimes, even using the same language, some nouns or jargons can change according to the country, states or even from Hospital to Hospital.

In this cases, you don't need to set an entire language again, you can extend languages creating a new folder inside a pre existent language folder and @ohif/i18n will do the hard work.

This new folder must to be called with a double character name, like the UK in the following file tree:

 |-- src
    |-- locales
    index.js
        |-- en
            |-- Buttons.json
            index.js
            | UK
               |-- Buttons.js
               indes.js
            | US
               |-- Buttons.js
               index.js
  ...

All properties inside a Namespace will be merged in the new sub language, e.g en-US and en-UK will merge the props with en, using i18next's fallback languages tool.

You will need to export all Json files in your index.js file, mounting an object like this:

{
  en: {
    NameSpace: {
      keyWord1: 'keyWord1Translation',
      keyWord2: 'keyWord2Translation',
      keyWord3: 'keyWord3Translation',
    }
  },
  'en-UK': {
    NameSpace: {
      keyWord1: 'keyWord1DifferentTranslation',
    }
  }
}

Please check the index.js files inside locales folder for an example of this exporting structure.

Extending languages dynamically

You have access to the i18next instance, so you can use the addResourceBundle method to add and change language resources as needed.

E.g.

import { i18n } from '@ohif/i18n';
i18next.addResourceBundle('pt-BR', 'Buttons', {
  Angle: 'Ângulo',
});

---

How to set a whole new language

To set a brand new language you can do it in two different ways:

• Opening a pull request for @ohif/i18n and sharing the translation with the community. 😍 Please see Contributing section for further information.

• Setting it only in your project or extension:

You'll need a a final object like the following, what is setting French as language, and send it to addLocales method.

const newLanguage =
   {
     fr: {
       Commons: {
          "Reset": "Réinitialiser",
          "Previous": "Précédent",
       },
       Buttons: {
         "Rectangle": "Rectangle",
         "Circle": "Cercle",
       }
     }

To make it easier to translate, you can copy the .json files in the /locales folder and theirs index.js exporters, keeping same keys and NameSpaces. Importing the main index.js file, will provide you an Object as expected by the method addlocales;

E.g. of addLocales usage

import { addLocales } from '@ohif/i18n';
import locales from './locales/index.js';
addLocales(locales);

You can also set them manually, one by one, using this method.

---

Language Detections

@ohif/i18n uses i18next-browser-languageDetector to manage detections, also exports a method called initI18n that accepts a new detector config as parameter.

Changing the language

OHIF Viewer accepts a query param called lng in the url to change the language.

E.g.

https://docs.ohif.org/demo/?lng=es-MX

Language Persistence

The user's language preference is kept automatically by the detector and stored at a cookie called 'i18next', and in a localstorage key called 'i18nextLng'. These names can be changed with a new Detector Config.

Debugging translations

There is an environment variable responsible for debugging the translations, called REACT_APP_I18N_DEBUG.

Run the project as following to get full debug information:

REACT_APP_I18N_DEBUG=true yarn run dev

Contributing with new languages

Contributions of any kind are welcome! Please check the instructions.