使用Gradle和CMake将发布和调试子目录添加到Android版本

Question

I'm trying to migrate an Android NDK project from Ant/ndk-build to Gradle/CMake. I want to build it from the command line on Windows. I don't want to use Android Studio. It's pretty much up and running now but there's one thing left to solve and that is the following:

In my CMakeFiles.txt I'm importing several other directories that contain static linker libraries into my project like this:

add_subdirectory("../foobar/src" "../foobar/obj/${ANDROID_ABI}")

Now the problem is with specifying the directory for the binary files. I'm already using ${ANDROID_ABI} to make sure the object and library files are separated by architecture. However, this isn't enough because Gradle will also do debug and release builds and with the line above, debug and release object and library files will be written to exactly the same directory and this will make Gradle rebuild each static library every time I say ./gradlew build .

So how can I solve this problem? Is there a variable that I can use in my CMakeLists.txt that tells me if Gradle/CMake is currently building for debug or for release? I've tried the following already, but it didn't work:

IF(CMAKE_BUILD_TYPE MATCHES DEBUG)
    set(BUILDMODE "Debug")
ELSE()
    set(BUILDMODE "Release")
ENDIF()

CMAKE_BUILD_TYPE always seems to be != DEBUG when building with Gradle and the Android plugin so BUILDMODE will always be Release .

I've been thinking about this for several hours now and I'm pretty much out of ideas... unfortunately, it also doesn't seem possible to leave out the binary files argument for CMake's add_subdirectory .

I really don't know what to do here so any help greatly appreciated.

Answer 1

According to @Andreas 's comment, here is how to use CMAKE_CURRENT_BINARY_DIR to detect Debug or Release variant in an Android NDK CMake build:

if (CMAKE_CURRENT_BINARY_DIR MATCHES "debug")
    message(STATUS "Debug build detected")
    add_compile_options("-DANDROID_DEBUG") # <-- change this to have an effect on the build
else()
    message(STATUS "Release build detected")
endif()

Answer 2

You may want to set it if not explicitly set upstream.

if (NOT CMAKE_BUILD_TYPE)
 SET(CMAKE_BUILD_TYPE Debug)
endif()