Cannot build shared libs in android due to undefined references in sample hello-android

[btut]

System information (version)

• OpenCV => commit 4c66772
• Operating System / Platform => macOS Sierra 10.12.1 / 64 Bit
• Compiler => Android NDK r13 (using g++ 4.9)

Detailed description

Cannot build OpenCV shared libraries for android due to undefined references in hello-android/main.cpp. Build works fine if I just set the main method in hello-android/main.cpp to do nothing and return 0.

CMakeFiles/hello-android.dir/hello-android/main.cpp.o:main.cpp:function main: error: undefined reference to 'cv::getTextSize(cv::String const&, int, double, int, int*)'
CMakeFiles/hello-android.dir/hello-android/main.cpp.o:main.cpp:function main: error: undefined reference to 'cv::putText(cv::InputOutputArray const&, cv::String const&, cv::Point, int, double, cv::Scalar_, int, int, bool)'
collect2: error: ld returned 1 exit status
make[3]: *** [bin/hello-android] Error 1
make[2]: *** [samples/android/CMakeFiles/hello-android.dir/all] Error 2

Steps to reproduce

build with the following commands:

cd OpenCV/platforms; \

mkdir -p build_android_arm; \

cd build_android_arm; \

cmake -DBUILD_SHARED_LIBS=ON -DANDROID_NATIVE_API_LEVEL=21 -DBUILD_EXAMPLES=OFF -DBUILD_DOCS=OFF -DBUILD_opencv_xfeatures2d=OFF -DWITH_CUDA=OFF -DWITH_OPENCL=ON -DOPENCV_EXTRA_MODULES_PATH=../../../OpenCVContrib/modules -DCMAKE_BUILD_WITH_INSTALL_RPATH=ON -DCMAKE_TOOLCHAIN_FILE=../android/android.toolchain.cmake $@ ../.. && \

make -j12

[alalek]

android-ndk-r10e works fine:
http://pullrequest.opencv.org/buildbot/builders/master_noOCL-android/builds/458

[btut]

I cannot confirm. I just tried with ndk r10e and it failed as well. I am unable to read from the buildbot if DBUILD_SHARED_LIBS is set, because I only get this error when building the shared libs, static libs work fine.

[dec1]

I confirm that I can reproduce this problem.

cd platforms
export PATH=/home/declan/Documents/zone/mid/bin/android/google/sdk/cmake/3.6.3155560/bin:$PATH
export ANDROID_NDK=/home/declan/Documents/zone/mid/bin/android/google/sdk/ndk-bundle

scripts/cmake_android_arm.sh  -DBUILD_SHARED_LIBS=ON -DANDROID_NATIVE_API_LEVEL=9 -DANDROID_STL=gnustl_shared

cd build_android_arm
make -j8

[ 60%] Built target opencv_superres /home/declan/Documents/zone/mid/bin/android/opencv/opencv_github_fork_dec1/samples/android/hello-android/main.cpp:16: error: undefined reference to 'cv::getTextSize(cv::String const&, int, double, int, int*)' /home/declan/Documents/zone/mid/bin/android/opencv/opencv_github_fork_dec1/samples/android/hello-android/main.cpp:18: error: undefined reference to 'cv::putText(cv::_InputOutputArray const&, cv::String const&, cv::Point_<int>, int, double, cv::Scalar_<double>, int, int, bool)' collect2: error: ld returned 1 exit status

Ive created a pull request that would resolve this:

#7678

samples/android/hello-android is not being linked to libopencv_imgproc.so