Building From Source

Building From Source

You don't need to build the AAR to use it (implementation("dev.ffmpegkit-maintained:tesseract-android:5.5.0")). These notes are for contributors and for reproducing the artifact.

Prerequisites

• JDK 17
• Android SDK, NDK r27c (27.2.12479018), CMake 3.22.1
• Ninja (apt-get install ninja-build)

sdkmanager "ndk;27.2.12479018" "cmake;3.22.1"

Clone with submodules

Leptonica and Tesseract are pinned git submodules:

git clone --recursive https://github.com/ffmpegkit-maintained/TesseractOCR.git
cd TesseractOCR
# or, if already cloned:
git submodule update --init --recursive

Submodule	Upstream	Pinned tag
leptonica	github.com/DanBloomberg/leptonica	1.84.1
tesseract	github.com/tesseract-ocr/tesseract	5.5.0

Build

./gradlew :library:assembleRelease
# → library/build/outputs/aar/library-release.aar

The native build (library/src/main/jni/CMakeLists.txt) does, in order:

1. Build Leptonica as libleptonica.so (BUILD_PROG=OFF, SW_BUILD=OFF).
2. Build Tesseract as libtesseract.so (training tools, curl, archive, graphics all disabled; OPENMP_BUILD=OFF for Free).
3. Build the JNI bridge libtesseract_jni.so, linking both.

All .so are linked with 16 KB max-page-size for Android 15 compatibility.

ABIs

Free builds arm64-v8a only (abiFilters in library/build.gradle.kts). The Pro variant adds x86_64.

Run the sample

./gradlew :sample:installDebug

Pick an image; it OCRs with the bundled English model and shows text + confidence.

Publishing

Handled by GitHub Actions:

• build-debug.yml — CI build on push/PR.
• build-release.yml — release AAR + GitHub Release on v* tags.
• publish-maven.yml — manual, verifies the native lib then publishes to Maven Central (irreversible; run only after validation).