Xposed Translate Text

Auto-translate app text with a local-first pipeline: local cache → on-device ML Kit (local server) → Gemini API → Free Google API.

What's New

3.0

• Translation speed improvements by shifting language-pair handling to the local server and reducing hook-side work.
• Refactored into a multi-module, multi-APK setup: full / hook-only / server-only.
• Supports unroot environments (tested with NPatch v0.7.3): patch target app with hook-only + install server-only.

2.0

• Prioritize on-device translation via a built-in local server using Google ML Kit.
• Added translation support for android.text.StaticLayout$Builder to reduce UI jank by replacing text synchronously when possible.

Installation & Setup

Root (LSPosed / Xposed)

Requirements:

• LSPosed (or another Xposed framework) installed and enabled.

Steps:

1. Install the full APK (app).
2. Open the LSPosed manager, enable XPTranslateText, and select your target apps.
3. Open the app, enable the "Local Translation Server" switch, and configure settings.
4. Force stop the target app and relaunch.

Unroot (NPatch / LSPatch)

Tested with:

• NPatch v0.7.3

Steps:

1. Patch the target app with app-hook (hook-only APK).
2. Install app-server (server-only APK).
3. Open app-server and start the local translation server (manual start).
4. Launch the patched target app.

Compatibility

• Android 13 with LSPosed (v1.9.2-it(7024))
• Android 15 with LSPosed (v1.9.2-it(7024))
• Android 16 with LSPosed (v1.9.2-it(7412))
• Unroot: NPatch v0.7.3 (hook-only + server-only)

Live Demo (Reddit Translation)

Before & After Comparison

Before	After

Project Structure

XPTranslateText/
├── app/                     # full APK (hook + server)
├── app-hook/                # hook-only APK (for NPatch/LSPatch patching)
├── app-server/              # server-only APK (manual start)
├── core-hook/               # hook entry + client (no UI)
├── core-server/             # local server + UI + resources
├── app/libs/                # Xposed/Android API stubs (compileOnly)
├── gradlew
├── gradlew.bat
├── keystore.properties      # Local-only, not committed
└── settings.gradle

Multiple APKs (full / hook-only / server-only)

• app (full): For normal root / LSPosed usage (one APK includes hook + local server + UI).
• app-hook (hook-only): For patchers like NPatch/LSPatch to embed the hook into a target app (no UI / no server).
• app-server (server-only): Standalone local translation server app (manually start/stop).

Build Commands (Gradle Wrapper)

• full Debug: ./gradlew :app:assembleDebug
• hook-only Debug: ./gradlew :app-hook:assembleDebug
• server-only Debug: ./gradlew :app-server:assembleDebug
• Requires Java 17 (macOS: export JAVA_HOME=$(/usr/libexec/java_home -v 17))

Local ML Kit Server

• Runs as a foreground service on 127.0.0.1:18181.
• Endpoint: /translate?q=... (src/dst are optional)
  • If src/dst are omitted, the server uses saved settings from xp_translate_text_configs.
  • src=auto enables automatic language detection (ML Kit Language ID).
• Endpoint: /config
  • Returns JSON: {"code":0,"source_lang":"auto","target_lang":"zh-TW","force_wait_local":false}
  • core-hook reads this to avoid XSharedPreferences (works for both root and unroot / NPatch scenarios).
  • Hook-side config cache TTL: 1s; when language pair changes, the in-memory translation cache is cleared.
• Models are downloaded on-demand and kept on-device; last-used times are tracked to help with maintenance.

Hook Methods & Translation Workflow

• android.widget.TextView & Custom Components:

  • Automatically translates text set via the setText() method.
  • Translation pipeline:
    1. Local Translation Cache (memory + SQLite) to avoid repeated work.
    2. Local ML Kit Server (on-device, 127.0.0.1:18181) with short timeouts to keep UI responsive.
    3. Gemini API (gemini-2.0-flash-lite) as network fallback.
    4. Free Google API as the final fallback.

• android.text.StaticLayout$Builder:

  • Intercepts StaticLayout.Builder.build() and attempts a synchronous replacement when translations are readily available (cache/DB) or quickly obtained from the local ML Kit server.
  • If not immediately available, it returns the original layout and prefetches translations asynchronously for subsequent renders.
  • Spans and formatting are preserved.

• android.webkit.WebView:

  • Performs real-time translation of visible webpage text via a JS bridge.
  • Pipeline: Local ML Kit Server → Gemini API → Free Google API (no caching for WebView).

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