# 縦書き Reader for Android

A standalone, immersive Narou reader powered by Mozilla GeckoView. The vertical
reading extension is bundled inside the APK; Firefox and Mozilla add-on signing
are not needed.

## Install

```
./build.sh
```

This is a development build for personal use, not a Play Store release.
The download final apk about 99 MiB because it includes the Firefox engine.
Keep `signing/debug.keystore`, for compatible future updates.

## Read

The first launch opens this page (because I'm lazy and picked the book I read):
https://ncode.syosetu.com/n0552ep/75/

- Swipe right to advance through the columns; swipe left to go back.
- Tap a paragraph to focus its text color. Tap the focused paragraph again or
  tap empty space to show or hide controls. Long-press still selects text.
- **文字**: font size; **行間**: column spacing; **段落**: paragraph spacing.
- **配色**: paper, white or dark theme.
- **自動**: open the reader automatically on chapter pages.
- **読書に戻る**: hide controls without changing the text layout.
- **元のページ**: show the original website; **縦書き** reopens the reader.
- **前へ / 目次 / 次へ**: chapter navigation.
- **☰**: open another Narou URL, reload, share, open in a browser, or view help.
- Android Back goes back through browsing history, then closes the Activity.
- Swipe from the system edge to temporarily reveal Android's system bars.

The screen is reserved for the text while reading. Controls overlay the page,
so opening them does not change the text layout. Camera cutouts are respected.

Paragraphs containing only `<br>` elements or whitespace are removed from the
reading copy. Empty span wrappers around breaks are handled too. Paragraphs
containing illustrations remain. Paragraph spacing is independent of column
spacing, with a 0–2em control and a default of 0.3em.

The app remembers the last Narou URL and saves normalized horizontal progress
for up to 200 chapter URLs. Position, font, column/paragraph spacing, theme and
auto-opening preference are local to this app. Progress is approximate when the
layout or chapter text changes. This version reads online; it does not download
whole books for offline use.

You can share a Narou chapter URL from another app to **縦書き Reader**. Opening
Narou links directly in the app may require enabling supported links in Android
App Info, because this personal app does not own or verify the site's domain.

## Build on macOS / Linux / Windows

Install a current Android Studio, or OpenJDK 27 (JDK 17 also works) and the Android command-line tools.
Install SDK Platform 37.2 and Build Tools 37.0.0 through SDK Manager. In Android
Studio open this directory, or set `ANDROID_HOME` to your SDK location.

The project uses Gradle 9.8.1, Android Gradle Plugin 9.4.1, and GeckoView
158.0.20261007201254. The Gradle wrapper is included. No machine-specific SDK
path is included in the source archive.

```sh
./build.sh                  # Build only; no adb/device required
./build.sh --install        # Build, then install on one connected device
./build.sh --serial DEVICE  # Build, then install on the selected device
./gradlew :app:lintDebug    # Optional Android lint check
```

`build.sh` uses your existing `JAVA_HOME` or Java from `PATH`, including OpenJDK 27.
It stops immediately on a failed build. Installation is opt-in; it checks for an
authorized device and selects ARM64 or x86_64 automatically. The Android bytecode
target remains Java 17, independently of the JDK used to run Gradle.

On Windows use `gradlew.bat`. Output:

```text
app/build/outputs/apk/debug/app-arm64-v8a-debug.apk
app/build/outputs/apk/debug/app-x86_64-debug.apk
```

The ARM64 build is for current phones; x86_64 is for emulator testing. Native
libraries are compressed in the APK to reduce download size. The included
development key is deliberately usable by the project; see `signing/README.md`.
Generate and protect a separate release key before any public distribution.

## Where to edit

- `app/src/main/java/net/astropenguin/naroureader/MainActivity.java`: app UI,
  immersive mode, URL navigation, back handling, sharing and native menus.
- `ReaderApplication.java` alongside it: process-wide Gecko runtime and extension installation.
- `app/src/main/assets/reader/content.js`: reading layout, text cleanup, controls,
  native touch scrolling and saved chapter positions.
- `app/src/main/assets/reader/manifest.json`: bundled extension registration.

The browser engine is bundled, so updating Firefox on the phone does not update
this app. Update the pinned GeckoView dependency and rebuild to ship engine fixes.

## Validation and limits

To run the bundled reader regression test, install Node.js and Playwright in a
temporary development environment, then run:

```sh
npm install --no-save playwright
npx playwright install firefox
node tests/reader.test.cjs
```

The test uses synthetic Japanese text; no copied novel is included. Japanese fonts
are needed for meaningful visual screenshots on Linux.

## Privacy and licenses

No app analytics or telemetry is added. Network access loads the original website
and its resources; its normal cookies and requests still apply. This app has its
own browser profile and does not share Firefox's cookies or logged-in accounts.
The reader is injected only on `https://ncode.syosetu.com/`. Other Syosetu pages
can be browsed normally; clicked external HTTPS links open in another browser.

App code is MIT-licensed. GeckoView is MPL 2.0 with third-party notices; see
`THIRD_PARTY_NOTICES.md` and app menu → About / help → Engine licenses.

## Changelogs

See [CHANGELOG](CHANGELOG.md)