It is possible to set cmake arguments per ABI in gradle?

Question

I have a crossplatform library with cmake based build script. Since cmake support for android is available now (https://developer.android.com/studio/projects/add-native-code.html), I plan to move ndk-build makefiles to the trash.
I've tested find_package(ZLIB REQUIRED) and it working well, because zlib headers and library itself is available for all ABI's in NDK sysroot. So, I can add any custom argument to cmake cmdline per flavor or build type:

buildTypes {
    release {
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        externalNativeBuild {
            cmake {
                arguments "-DMYLIB_ENABLE_PROGUARD=ON"
            }
        }
    }
    debug {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        externalNativeBuild {
            cmake {
                arguments "-DMYLIB_ENABLE_PROGUARD=OFF"
            }
        }
    }
}

My issue is in ability to set CMAKE_PREFIX_PATH per ABI to find external static/shared libs via FindPackage.

Generally, I can use find_library and include_directories in conjunction with ${ANDROID_ABI} in cmake script itself, but I already have working script with multiple platform support, I don't wan't to add dirty code, because there is the clean way (find_package + CMAKE_PREFIX_PATH).

Thank you all for your time!

Answer 1

This is not something that we currently support. I think it should be possible though. I opened b.android.com/225884 to track it.

Answer 2

if you are just after ABI you can do things like

if(${ANDROID_ABI} STREQUAL "x86_64")
    # ABI xx
endif()

This works very well and does not feel like a hack. I use it for building OpenSSL (complete usage here: https://github.com/schwabe/platform_external_openssl/blob/icsopenvpn/openssl.cmake)

If you need really flavours... I came up with this super ugly hack for flavours:

cmake
# Super hacky way to determine if flavour is normal
# cmake is called with the DCMAKE_LIBRARY_OUTPUT_DIRECTORY that includes the flavour (and archtecture)
#-DCMAKE_LIBRARY_OUTPUT_DIRECTORY=/Users/arne/software/icsopenvpn/main/build/intermediates/cmake/normal/debug/obj/arm64-v8a
if (${CMAKE_LIBRARY_OUTPUT_DIRECTORY} MATCHES "build/intermediates/cmake/.*normal.*/")
  # Flavour specific
endif()