Install Flutter by following the official doc: https://docs.flutter.dev/get-started/install
Download and install Android Studio to develop for Android: https://developer.android.com/studio
Start Android Studio, and go through the ‘Android Studio Setup Wizard’. This installs the latest Android SDK, Android SDK Command-line Tools, and Android SDK Build-Tools, which are required by Flutter when developing for Android.
Run flutter doctor to confirm your installation is working. You should see some output like below. At a minimum you should have [✓] Flutter and [✓] Android toolchain to develop for Android, the other check marks are optional.

[✓] Flutter (Channel stable, 3.19.3, on Ubuntu 20.04.6 LTS 6.2.0-1019-azure, locale C.UTF-8)
[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
[✗] Chrome - develop for the web (Cannot find Chrome executable at google-chrome)
    ...
[✗] Linux toolchain - develop for Linux desktop
    ...
[!] Android Studio (not installed)
[✓] Connected device (1 available)
[✓] Network resources

If you want to build for iOS, you are required to use a Mac. You will need the latest version of Xcode as well.

Run the setup.sh at the root of this project to install the Rust backend.
Run flutter run to run the app, or
- flutter build appbundle to create an Android app bundle
- flutter build apk to build an Android APK
- flutter build ios to build for iOS

Notes:

Build command for F-Droid (which forbids proprietary components like Google's MLKit): flutter build appbundle --flavor foss
Build command for Huawei AppGallery (which forbids sensitive content): flutter build appbundle --flavor huawei
Build command for Google Play Store (full version): flutter build appbundle --flavor full

Release Checklist

Bump app version in pubspec.yaml

Open the wordshk-tools project and update the app version in examples/export_sqlite_db/src/main.rs:

- api.export_dict_as_sqlite_db(&dict_path, "{old_version}")
+ api.export_dict_as_sqlite_db(&dict_path, "{new_version}")

Regenerate dictionary data with updated words.hk content a. Download the latest CSV from https://words.hk/faiman/request_data/ b. Open the wordshk-tools project and replace the old wordshk.csv with the downloaded one c. Remove the first two autogenerated comments in the CSV d. Regenerate dict.db.gz:
```
cd export_sqlite_db/
cargo run --release
gzip app_tmp/dict.db
```
Copy the two files back to this project. Copy the dict.db.gz back to assets/.
Generate TTS recordings for new sentences a. Regenerate dict.json by going to examples/export_json_dict and run cargo run --release b. Copy the generated app_tmp/dict.json to project root c. Generate TTS by going to tts/, activate conda environment conda activate wordshk, and run python tts.py d. Upload newly generated audios to Alicloud OSS bucket by running python upload_to_bucket.py

Build iOS and Android binaries:

flutter clean
flutter pub get
cd ios/
pod install
cd ..
# Go to Xcode and Product -> Archive
flutter build appbundle --flavor full

TAG the commit for F-droid.

Normalize jyutping syllable audios

Open Adobe Audition, run the "Match Loudness" with these settings:
- ITU-R BS.1770-3 Loudness
- Target Loudness: -16 LUFS
- Tolerance: 2 LU
- Max True Peak Level: -2 dBTP
- Look-ahead Time: 12ms
- Release Time: 200ms
Export the files with matched loudness With export settings as follows:
- Format MP3
- Sample Type: Same as source
- Format settings: MP3 24 Kbps CBR (Constant type)
Change directory into assets/jyutping_female or assets/jyutping_male.
Run process_audios.sh. This script does three things:
1. Trim silence at the beginning and end of all mp3 files
2. Pad the end of jap6sing1 syllables so they are not too short
3. Peak normalize jap6sing1 syllables to make they as loud as other syllables

Legal

"words.hk", "wordshk", "粵典" are trade names of Hong Kong Lexicography Limited. Permission by Hong Kong Lexicography Limited must be obtained to promote or distribute materials containing these names. In particular, notwithstanding any permission (if applicable) to redistribute the source code of this project and/or its derivative works by the copyright owner(s), unless you obtain explicit permission from Hong Kong Lexicography Limited, you are required to remove all mentions of "words.hk", "wordshk", "粵典" from your redistributions.

The dictionary contents published by words.hk is copyrighted by Hong Kong Lexicography Limited. You may be eligible to obtain a license from https://words.hk/base/hoifong/