Android NDK, CMake with other libraries - android-ndk

Question

So I am trying to build and test out a CMake with the Android NDK on Android Studio. I can get my library to compile, but it doesn't seem to want to pull any third-party dependencies over. I've been reading through the toolchain and looking for better documentations, with no luck. Can someone tell me if I am missing?
cmake_minimum_required(VERSION 3.4.1)
set(SFML_PATH ${ANDROID_NDK}/sources/sfml)
set(SFML_LIB_PATH ${SFML_PATH}/lib/${ANDROID_NDK_ABI_NAME})
set(SFML_LIB_SYSTEM ${SFML_LIB_PATH}/libsfml-system.so)
set(SFML_LIB_AUDIO ${SFML_LIB_PATH}/libsfml-audio.so)
set(SFML_LIB_GRAPHICS ${SFML_LIB_PATH}/libsfml-graphics.so)
set(SFML_LIB_NETWORK ${SFML_LIB_PATH}/libsfml-network.so)
set(SFML_LIB_WINDOW ${SFML_LIB_PATH}/libsfml-window.so)
set(SFML_LIB_ACTIVITY ${SFML_LIB_PATH}/libsfml-activity.so)
set(SFML_LIB_MAIN ${SFML_LIB_PATH}/libsfml-main.a)
set(SFML_LIBS ${SFML_LIB_SYSTEM} ${SFML_LIB_GRAPHICS} ${SFML_LIB_AUDIO} ${SFML_LIB_WINDOW} ${SFML_LIB_ACTIVITY})
include_directories(${SFML_PATH}/include)
link_directories(${SFML_LIB_PATH})
add_library(native-lib SHARED
src/main/cpp/native-lib.cpp)
target_link_libraries(native-lib log ${SFML_LIBS})
#file(COPY ${SFML_LIBS} DESTINATION ${__android_install_path})
FOREACH(SFML_LIB ${SFML_LIB})
execute_process( COMMAND "${CMAKE_COMMAND}" -E copy_if_different "${SFML_LIB}" "${LIBRARY_OUTPUT_PATH}/${SFML_LIB}" RESULT_VARIABLE __fileCopyProcess )
MESSAGE("Lib: ${SFML_LIB}")
ENDFOREACH(SFML_LIB)
Above is my CMakeLists.txt. I have done a little hacking to get it to compile with SFML with the paths, as I have not found good documentation with CMake and Android yet.

Answer 1

May you add more info for:
"but it doesn't seem to want to pull any third-party dependencies over."?
this one:
https://github.com/googlesamples/android-ndk/tree/master/hello-libs
has static and shared 3rd party libs, you may try it.
For the shared dependent lib, you will need to pack them into APK, that is done inside gradle, cmake will not do it.
The above example shows that, basically they need to be copied into your app/src/main/jniLibs too so they will be packed into apk, and pushed to your android phone/tablet. At runtime they could be loaded.
I have tried to put a group of libraries into one directory, and use
link_directories(...)
then just put the lib names directly into
target_link_libraries(...)
also works. Make sure you have the right libs for the ABIs you intend to support for your app [looks like you are just building for one ABI].

Answer 2

The process could be little long it will depend on your android skills.
An example could be similar to this process:
Crosscompile sfml.
Create your jni bridge
Generate with cmake the project and compile
Copy your files to android studio. create java loading library code.
I guess that you have crosscompiled sfml and you know how works crosscompiling process, if I am wrong check these link below:
Tutorial:
https://github.com/SFML/SFML/wiki/Tutorial:-Building-SFML-for-Android
Source code:
https://github.com/SFML/SFML
Toolchain:
https://github.com/SFML/SFML/blob/master/cmake/toolchains/android.toolchain.cmake
Changes on your cmake:
add this file
FIND_PACKAGE(SFML required)
In cmake put your SFML build directory and cmake will fills your VARIABLES
automatically for instance this variables:
set(SFML_PATH ${ANDROID_NDK}/sources/sfml)
set(SFML_LIB_PATH ${SFML_PATH}/lib/${ANDROID_NDK_ABI_NAME})
set(SFML_LIB_SYSTEM ${SFML_LIB_PATH}/libsfml-system.so)
set(SFML_LIB_AUDIO ${SFML_LIB_PATH}/libsfml-audio.so)
set(SFML_LIB_GRAPHICS ${SFML_LIB_PATH}/libsfml-graphics.so)
set(SFML_LIB_NETWORK ${SFML_LIB_PATH}/libsfml-network.so)
set(SFML_LIB_WINDOW ${SFML_LIB_PATH}/libsfml-window.so)
set(SFML_LIB_ACTIVITY ${SFML_LIB_PATH}/libsfml-activity.so)
set(SFML_LIB_MAIN ${SFML_LIB_PATH}/libsfml-main.a)
There are two ways to make android studio native apps:
Easy way:
Create JNI bridge:
Crosscompile your cmake script and copy your lib to app/src/main/jniLibs
add library in execution time
code:
try
{
Log.v(LOG_TAG, "adding your library");
System.loadLibrary(your_library);
}
catch(UnsatisfiedLinkError e)
{
Log.e(LOG_TAG,e.getMessage());
}
More complete way (it allows to debug library)
Create your ndk module in gradle
example
android.ndk {
moduleName = "your_library"
cppFlags.add("-fexceptions")
//cppFlags.add("-std=c++11")
//cFlags.add("-fopenmp")
cppFlags.add("-I" + file("src/main/jni").absolutePath)
stl = "gnustl_shared" // Which STL library to use: gnustl or stlport
ldLibs.addAll(["android", "EGL", "GLESv2", "dl", "log", "z"])
String libsDir = curDir.absolutePath + "/src/main/jniLibs/armeabi/"
ldLibs.add(libsDir + "your_native_lib.so")
}