Go Native: Integrating Native Code on Android

Transcript

1. sergiomarquesmoura Go Native: Integrating native code on Android Sérgio Moura
2. Why native code? ➔ Java is slow ◆ Arithmetic tasks ◆ Image processing ➔ Gradle support ◆ Cmake ◆ ndk-build ➔ Research teams do it native ◆ C/C++
3. Git Submodules
4. [submodule "glare_detector"] path = onfido-capture-sdk/src/main/jni/edge_detector url = git@bitbucket.org:onfido/edge_detector.git ➔ Name ➔ Path ➔ Url $ git submodule update --init
6. Compiling the code
8. But why compiling?
9. Why compiling native code? ➔ Multiple devices ◆ Wide range of CPUs • Multiple instruction sets ➔ Solution: ABIs (Application Binary Interface) ◆ armeabi-v7a ◆ arm64-v8a ◆ x86 ◆ x86_64
10. android { ... defaultConfig { ... externalNativeBuild { cmake { abiFilters 'armeabi-v7a', 'arm64-v8a', 'x86', 'x86_64' } } } externalNativeBuild { cmake { path 'src/main/jni/CMakeLists.txt' } } }
11. cmake_minimum_required(VERSION 3.6) project(NativeBridge) add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/glare_detector) add_library(GlareBridge SHARED GlareBridge.cpp) target_link_libraries(GlareBridge GlareDetector)
12. Building the bridge
13. extern "C" { JNIEXPORT jobjectArray JNICALL Java_com_onfido_android_sdk_capture_native_1detector_NativeDetector_detectGla re(JNIEnv *, jobject, jbyteArray, jint, jint, jint, jint, jint, jint, jint, jint); }
14. Back to Java
15. public class NativeDetector { static { System. loadLibrary("GlareBridge"); } public native double[][] detectGlare(byte[] imageData, int width, int height, int rectWidth, int rectHeight, int rectLeft, int rectTop, int numRows, int numCols); } new NativeDetector().detectGlare( … );
16. Thank you! Questions?