Running CMake from command line within an Android

问题:

How might one run an NDK Cmake build independently from the rest of an Android project, ideally from the command line, external to Android Studio?

The equivalent of running ndk-build from the jni directory for slightly older Android NDK projects.

I need to investigate exactly what the calls to the compiler look like, and I can't seem to get this information when building the whole project from within Android Studio

My first attempt was just to run cmake from the project/app directory containing CMakeLists.txt, but this informs me that cmake is not installed - so how is Android Studio managing to build it then?

回答1:

If your goal is to just run from the command line (as opposed to trying to do exactly what gradle is doing), just use cmake the way you normally would:

$ cmake -DCMAKE_TOOLCHAIN_FILE=$NDK/build/cmake/android.toolchain.cmake \
    -DANDROID_ABI=whatever $YOUR_SOURCE_DIR

Alternatively, you can just run ./gradlew from the command line.

回答2:

Your original problem is that you cannot see the command-line invocation when building with Android Studio.

You can get the command line arguments to the compiler by editing your app/build.gradle file.

defaultConfig {
    ...
    externalNativeBuild {
        cmake {
            ...
            arguments "-DCMAKE_VERBOSE_MAKEFILE=1", ...
        }
    }

}

In Adroid Studio's Gradle Console pane, you will then see the command line for the compiler and linker like so:

[1/176] /home/bram/android-sdk-linux/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/bin/clang --target=armv7-none-linux-androideabi --gcc-toolchain=/home/bram/android-sdk-linux/ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64 --sysroot=/home/bram/android-sdk-linux/ndk-bundle/sysroot -isystem /home/bram/android-sdk-linux/ndk-bundle/sysroot/usr/include/arm-linux-androideabi -D__ANDROID_API__=19 -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -march=armv7-a -mfloat-abi=softfp -mfpu=vfpv3-d16 -fno-integrated-as -marm -mfpu=neon -Wa,--noexecstack -Wformat -Werror=format-security -Os -DNDEBUG -fPIC -MD -MT /home/bram/src/GPGOAP/CMakeFiles/gpgoap.dir/astar.c.o -MF /home/bram/src/GPGOAP/CMakeFiles/gpgoap.dir/astar.c.o.d -o /home/bram/src/GPGOAP/CMakeFiles/gpgoap.dir/astar.c.o -c /home/bram/src/GPGOAP/astar.c

回答3:

As detail to the accepted answer:

The complete set of parameters passed to CMake is written to:

<project-root>/<module-root>/.externalNativeBuild/cmake/<build-type>/<ABI>/cmake_build_command.txt`

See for details: https://developer.android.com/ndk/guides/cmake.html#build-command