Build OpenCV for Android with LLVM C++

README.md

Download OpenCV:

$ export OPENCV_VERSION=3.4.3
$ git co opencv_contrib && cd opencv_contrib && git co $OPENCV_VERSION
$ git co opencv
$ cd opencv
$ git co $OPENCV_VERSION
$ mkdir build-arm

Run ./cmake-gui to generate Makefile's.

1. Click the Browse Source button and give the OpenCV source folder.
2. Click the Browse Build button and give the build folder: build-arm
3. Click Configure button, select Specify toolchain file for cross-compiling. In the next prompt window, make sure to select the android.toolchain.cmake under $HOME_NDK/build/cmake/. Make sure not to use the file under opencv folder.
4. Add entries:

• Set ANDROID_PLATFORM to android-23 (or any other)
• Set ANDROID_STL to c++_static
• Set BUILD_ANDROID_PROJECTS to false (skip Gradle problems)
• Set BUILD_ANDROID_EXAMPLES to false
• Set CMAKE_BUILD_TYPE to Release
• Set OPENCV_EXTRA_MODULES_PATH to opencv_contrib/modules
• Set OPENCV_ENABLE_NONFREE to true

5. Click Configure and Generate

Build and install:

$ cd build-arm
$ make -j1
$ make install

References:

• https://zami0xzami.wordpress.com/2016/03/17/building-opencv-for-android-from-source/
• http://discuz-android.blogspot.com/2017/10/build-opencv-for-android-with-llvm-c.html
• opencv/opencv#7174