OpenCV - undefined reference to 'cv::CascadeClassifier::detectMultiScale() after NDK update

Question

Yesterday I updated my Android Studio included NDK to version 17.0.4754217and since then I can\'t run my app anymore. When I tried to rerun the code after the u

Answer 1

A more complete answer for all the seekers out there. Using OpenCV prebuilt static libraries in your project with a native component.

This is what I have for the build.gradle:

defaultConfig {
    minSdkVersion 21
    targetSdkVersion 21
    externalNativeBuild {
        cmake {
            cppFlags "-fexceptions -std=gnu++11"
            arguments '-DANDROID_STL=gnustl_static'
        }
    }
    ndk {
        // Specifies the ABI configurations of your native
        // libraries Gradle should build and package with your APK.
        abiFilters 'armeabi-v7a', 'x86'
        stl = "gnustl_shared"
    }
}

This is the CMakeLists.txt:

set(OPENCV_LIBRARIES ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_NDK_ABI_NAME}/libopencv_video.a
                     ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_NDK_ABI_NAME}/libopencv_imgproc.a
                     ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_NDK_ABI_NAME}/libopencv_core.a
                     ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_NDK_ABI_NAME}/libopencv_highgui.a
                     ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_NDK_ABI_NAME}/libtbb.a
                     ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_NDK_ABI_NAME}/libcpufeatures.a
                     )

if (${ANDROID_ABI} STREQUAL "x86")
    set(OPENCV_LIBRARIES ${OPENCV_LIBRARIES}
                         ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_NDK_ABI_NAME}/libippiw.a
                         ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_NDK_ABI_NAME}/libippicv.a
                         ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_NDK_ABI_NAME}/libittnotify.a
                         )
    set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--exclude-libs,libippicv.a -Wl,--exclude-libs,libippiw.a")
endif()

if (${ANDROID_ABI} STREQUAL "armeabi-v7a")
    set(OPENCV_LIBRARIES ${OPENCV_LIBRARIES}
                         ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_NDK_ABI_NAME}/libtegra_hal.a
                         )
endif()

(then use ${OPENCV_LIBRARIES} for your target_link_libraries)