Android undefined reference with NDK

Question

I'm trying to implement code from

here

When trying to compile it, I get these errors:

Error:(339) undefined reference to `ANativeWindow_fromSurface'
Error:(340) und
Error:(349) undefined reference to `ANativeWindow_setBuffersGeometry'
Error:(351) undefined reference to `ANativeWindow_lock'
Error:(353) undefined reference to `ANativeWindow_release'
Error:(406) undefined reference to `ANativeWindow_unlockAndPost'
Error:(407) undefined reference to `ANativeWindow_release'
Error:error: linker command failed with exit code 1 (use -v to see invocation)
Information:BUILD FAILED
Information:Total time: 2.012 secs
Information:8 errors
Information:0 warnings
Information:See complete output in console

ANativeWindow gets from 2 c++ .h files, one is

#include <android/native_window.h>

and other

 #include <android/native_window_jni.h>

Now, my CMake file looks like this:

cmake_minimum_required(VERSION 3.4.1)

# OpenCV stuff
include_directories(D:\\opencv-3.2.0-android-sdk\\OpenCV-android-sdk\\sdk\\native\\jni\\include)
add_library( lib_opencv SHARED IMPORTED )
set_target_properties(lib_opencv PROPERTIES IMPORTED_LOCATION ${CMAKE_CURRENT_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI}/libopencv_java3.so)
add_compile_options(-std=c++11)

# Creates and names a library, sets it as either STATIC
# or SHARED, and provides the relative paths to its source code.
# You can define multiple libraries, and CMake builds them for you.
# Gradle automatically packages shared libraries with your APK.

add_library( # Sets the name of the library.
             native-lib

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             src/main/cpp/native-lib.cpp)

# Searches for a specified prebuilt library and stores the path as a
# variable. Because CMake includes system libraries in the search path by
# default, you only need to specify the name of the public NDK library
# you want to add. CMake verifies that the library exists before
# completing its build.

find_library( # Sets the name of the path variable.
              log-lib

              # Specifies the name of the NDK library that
              # you want CMake to locate.
              log )

# Specifies libraries CMake should link to your target library. You
# can link multiple libraries, such as libraries you define in the
# build script, prebuilt third-party libraries, or system libraries.

target_link_libraries( # Specifies the target library.
                       native-lib
                       -ljnigraphics
                       lib_opencv

                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib} )

And my gradle file regarding c++ code:

defaultConfig {
        minSdkVersion globalConfiguration.getAt("androidMinSdkVersion")
        targetSdkVersion globalConfiguration.getAt("androidTargetSdkVersion")

        applicationId globalConfiguration.getAt("androidApplicationId")
        versionCode globalConfiguration.getAt("androidVersionCode")
        versionName globalConfiguration.getAt("androidVersionName")
        testInstrumentationRunner globalConfiguration.getAt("testInstrumentationRunner")
        testApplicationId globalConfiguration.getAt("testApplicationId")
        externalNativeBuild {
            cmake {
                cppFlags "-frtti -fexceptions -Werror -fexceptions -std=c++11"
                abiFilters 'x86', 'x86_64', 'armeabi', 'armeabi-v7a', 'arm64-v8a', 'mips', 'mips64'
            }
        }
        multiDexEnabled = true
    }
    externalNativeBuild {
        cmake {
            path "CMakeLists.txt"
        }
    }
    sourceSets {
        main {
            jniLibs.srcDirs = ['src/main/jniLibs']
        }
    }

I would appreciate if someone would help me with this

Answer 1

You need to link against libandroid.

target_link_libraries( # Specifies the target library.
                       native-lib
                       -ljnigraphics
                       -landroid # Add this.
                       lib_opencv

                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib} )