LeanType OCR Plugin

An offline Optical Character Recognition (OCR) plugin for LeanType (and HeliBoard), enabling instant on-device text recognition directly from your keyboard.

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✨ Features

• 🔒 100% Offline & Private: Zero network permissions. All vision and neural models run entirely on-device with zero data telemetry.
• ⚡ Bundled ML Kit V2 Engines: Uses Google ML Kit's bundled offline models for high-accuracy recognition across multiple scripts:
  • Latin (English, Spanish, French, German, etc.)
  • Devanagari (Hindi, Marathi, Sanskrit, etc.)
  • Chinese (Simplified & Traditional)
  • Japanese (Kanji, Hiragana, Katakana)
  • Korean (Hangul)
• 🧩 Lightweight Plugin Architecture: Dynamically loaded on demand via Android DexClassLoader with zero background battery or memory overhead when idle.
• 📱 Multi-Architecture Support: Pre-configured ABI splits (arm64-v8a, armeabi-v7a, x86, x86_64) for minimal download and install sizes.

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🚀 Installation & Usage

1. Download & Install

Download the latest APK matching your device's CPU architecture (typically arm64-v8a for modern Android devices) from the Releases section and install it.

2. Enable in LeanType Keyboard

1. Open LeanType Settings.
2. Navigate to Advanced $\to$ Plugins.
3. Select OCR Plugin and verify the status shows Active / Connected.
4. Use the OCR action from the keyboard toolbar or long-press action to scan and insert text anywhere.

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🛠️ Building from Source

Prerequisites

• Android Studio Ladybug or later / Android SDK Platform 34
• JDK 17
• Gradle 8.2+

Build Commands

# Clone the repository
git clone https://github.com/LeanBitLab/LeanType-OCR-Plugin.git
cd LeanType-OCR-Plugin

# Build Debug APKs for all ABIs
./gradlew assembleDebug

# Build Release APKs (configured with ProGuard/R8 optimization)
./gradlew assembleRelease

Generated APKs will be located in:

app/build/outputs/apk/{debug,release}/ocr_plugin-{abi}.apk

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📐 Architecture & Plugin Interface

LeanType loads this plugin dynamically at runtime through a standardized interface contract:

package helium314.keyboard.latin.ocr

interface ITextRecognizer {
    suspend fun recognizeText(bitmap: Bitmap): String
}

Implementation is managed by TextRecognizerImpl in helium314.keyboard.ocr.plugin, which initializes the bundled TextRecognition clients on demand and processes image frames asynchronously using Kotlin Coroutines.

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📄 License

This project is licensed under the GNU General Public License v3.0 (GPL-3.0) - see the LICENSE file for details.