add possibility to test locales locally

https://github.com/mifi/lossless-cut/issues/1500#issuecomment-1461780597

README.md

@@ -169,7 +169,7 @@ Unsupported files can still be converted to a supported format/codec from the `F
 
 ## [Command line interface (CLI)](cli.md)
 
-## [Developer notes](developer-notes.md)
+## [Contributing](developer-notes.md)
 
 ## [Known issues, limitations, troubleshooting, FAQ](issues.md)
 

developer-notes.md

@@ -1,7 +1,41 @@
-## Development
+# Contributing
+
+## Translators
+
+You are welcome to help translate the app at [Weblate](https://hosted.weblate.org/projects/losslesscut/losslesscut/). Weblate will automatically push translations as a Pull Request in this repo, but this PR is not merged immediately by maintainers.
+
+Master language is english.
+
+### Testing translations locally
+
+To test new weblate translations you made in the app itself, you need to:
+1. Download the translation for your language from Weblate: **Files -> Download translation**
+2. Rename the downloaded `.json` file to: `translation.json`
+3. Create a [folder structure](https://github.com/mifi/lossless-cut/tree/master/public/locales) somewhere on your computer that looks like this:
+```
+translations/locales/localeCode
+```
+You can find a list of the available [`localeCode`s here](https://github.com/mifi/lossless-cut/tree/master/public/locales). In our example we will use `nb_NO` (Norwegian) with this path:
+```
+/Users/mifi/Desktop/translations/locales/nb_NO
+```
+
+4. Now move your `translation.json` file into the folder:
+```
+/Users/mifi/Desktop/translations/locales/nb_NO/translation.json
+```
+
+5. Now run LosslessCut from the [command line](cli.md), with the special command line argument `--locales-path`. Use the path to the **folder containing the locales folder**, e.g.:
+```bash
+./LosslessCut --locales-path /Users/mifi/Desktop/translations
+```
+
+Now LosslessCut will use your language file.
+
+## Development setup
 
 This app is built using Electron.
-Make sure you have at least Node v14. The app uses ffmpeg from PATH when developing.
+Make sure you have at least Node v16. The app uses ffmpeg from PATH when developing.
 
 ```bash
 npm install -g yarn
@@ -12,6 +46,7 @@ git clone https://github.com/mifi/lossless-cut.git
 cd lossless-cut
 yarn
 ```
+
 Note: `yarn` may take some time to complete.
 
 ### Installing `ffmpeg`

public/electron.js

@@ -18,6 +18,8 @@ const { frontendBuildDir } = require('./util');
 
 const { checkNewVersion } = require('./update-checker');
 
+const i18nCommon = require('./i18n-common');
+
 require('./i18n');
 
 const { app, ipcMain, shell, BrowserWindow, nativeTheme } = electron;
@@ -156,6 +158,9 @@ function parseCliArgs(rawArgv = process.argv) {
 
 const argv = parseCliArgs();
 
+if (argv.localesPath != null) i18nCommon.setCustomLocalesPath(argv.localesPath);
+
+
 function safeRequestSingleInstanceLock(additionalData) {
   if (process.mas) return true; // todo remove when fixed https://github.com/electron/electron/issues/35540
 

public/i18n-common.js

@@ -6,7 +6,16 @@ const { join } = require('path');
 
 const { frontendBuildDir } = require('./util');
 
-const getLangPath = (subPath) => (isDev ? join('public', subPath) : join(app.getAppPath(), frontendBuildDir, subPath));
+let customLocalesPath;
+function setCustomLocalesPath(p) {
+  customLocalesPath = p;
+}
+
+function getLangPath(subPath) {
+  if (customLocalesPath != null) return join(customLocalesPath, subPath);
+  if (isDev) return join('public', subPath);
+  return join(app.getAppPath(), frontendBuildDir, subPath);
+}
 
 // Weblate hardcodes different lang codes than electron
 // https://www.electronjs.org/docs/api/app#appgetlocale
@@ -47,4 +56,10 @@ const commonI18nOptions = {
 const loadPath = (lng, ns) => getLangPath(`locales/${mapLang(lng)}/${ns}.json`);
 const addPath = (lng, ns) => getLangPath(`locales/${mapLang(lng)}/${ns}.missing.json`);
 
-module.exports = { fallbackLng, loadPath, addPath, commonI18nOptions };
+module.exports = {
+  fallbackLng,
+  loadPath,
+  addPath,
+  commonI18nOptions,
+  setCustomLocalesPath,
+};