Thanks this is very helpful. The other question I have is: Is there a place to centrally specify the root CMakeLists.txt? Basically, I want to specify the CMake root in 1 place, and have targets (defined further down in subdirectories) that require APK packaging to specify only the native target name that should be built & packaged.
At the moment we specify the root CMakeLists.txt by walking up the tree, paths like "../../../../CMakeLists.txt". I think this should be put at the top-level build gradle file if possible. Is this doable at the moment? What is the recommended setup? On Mon, Aug 21, 2017 at 9:37 AM, Jom O'Fisher <jomofis...@gmail.com> wrote: > Gradle does introspection on the CMake build to find .so targets and those > get packaged. > There is also a special case for stl/runtime .so files from the NDK. > Any additional .so files need to specified in build.gradle using jniDirs > > On Mon, Aug 21, 2017 at 7:30 AM, Robert Dailey <rcdailey.li...@gmail.com> > wrote: >> >> How exactly does Gradle package *.so files in an APK? I know that ANT >> used to do this for any libs under "libs/<ABI>". Does Gradle do some >> introspection into CMake targets to see if outputs are *.so, and copy >> those to some location if needed? What about libraries like >> libgnustl_shared.so that come with the NDK? I'd like to know if any >> manual copy steps are needed in CMake to put outputs in proper >> locations for the APK build step. I had to do this when using ANT. >> >> On Mon, Aug 7, 2017 at 6:16 PM, Jom O'Fisher <jomofis...@gmail.com> wrote: >> > 1) There is a folder created for each ABI under the project module >> > folder >> > (so unique per module per ABI) >> > 2) Gradle doesn't specify language level though you can choose to >> > specify it >> > yourself from the build.gradle. This doc does a pretty good job of >> > explaining which variables are set by Gradle: >> > https://developer.android.com/ndk/guides/cmake.html#variables. >> > Philosophically, we try to set as little as we can get away with. In >> > particular, the section titled "Understanding the CMake build command" >> > lays >> > out exactly what we set. You can also see the folders we specify (one >> > per >> > module per ABI) >> > 3) Not sure I understand this. >> > >> > The other document worth taking a look at (if you haven't already) is: >> > https://developer.android.com/studio/projects/add-native-code.html >> > >> > >> > On Mon, Aug 7, 2017 at 3:35 PM, Robert Dailey <rcdailey.li...@gmail.com> >> > wrote: >> >> >> >> Thanks Jom >> >> >> >> Honestly, I prefer option 1 to work simply because that's how Google's >> >> officially supporting CMake. But it also has debugging which is the #1 >> >> reason for me. >> >> >> >> However, I'd like to understand a lot more about how the integration >> >> really happens. For example, I have these questions: >> >> >> >> 1) How, internally, are CMake build directories managed? Do you >> >> generate 1 per unique android project? What about for each specific >> >> platform (x86, armeabi-v7a, etc)? >> >> 2) Last time I looked into CMake integration, things defined inside >> >> the CMake scripts were ignored because they are specified at the >> >> command line. Namely, all of those settings that are driven by the >> >> Gradle configuration (CXX language level was one in particular I >> >> think; I specify C++14 support via CMake, but I recall this being >> >> overridden from outside)? >> >> 3) How redundant is it to configure individual libraries via the >> >> gradle scripts? In my previous attempts, I wanted to define common >> >> stuff for CMake / native code at the root gradle or settings file, and >> >> only define the differences in the actual gradle build files for each >> >> corresponding Java target (like, defining the name of the native >> >> (shared library) target in Gradle, but the command line invocation, -D >> >> CMake settings, etc would all be common and defined at the root). >> >> >> >> The TLDR is, the closer we can stay to CMake's way of doing things and >> >> keep CMake-related settings self-contained to the CMake scripts >> >> themselves, the better. This also makes cross-platform easier (we >> >> build the native code in Windows, for example, so having settings >> >> specified in the gradle files do not carry over to other platforms. >> >> Namely, settings that are not platform specific like the C++ language >> >> level). >> >> >> >> If there's a detailed document / wiki I can read on the intrinsics of >> >> CMake integration in Gradle / Android Studio, I'd love to read it. >> >> Otherwise, I hope you won't mind if I pick your brain as questions >> >> come up. I think I'm going to try option 1 for now and see how it >> >> goes. It's just black box for me because unlike option 2, I have very >> >> little control over what happens after building the shared libraries, >> >> and to make up for that I need to really get a deep understanding of >> >> how it works so I can make sure I code my CMake scripts properly for >> >> not only Android, but my other platforms as well (non-Android >> >> platforms). >> >> >> >> Thanks again. >> >> >> >> On Mon, Aug 7, 2017 at 5:12 PM, Jom O'Fisher <jomofis...@gmail.com> >> >> wrote: >> >> > Either option can work fine. Disclosure: I work on Android Studio and >> >> > was >> >> > the one that added CMake support. >> >> > >> >> > Option (1) is the way it's designed to work and we're working toward >> >> > getting >> >> > rid of the need for the CMake fork. I can't really say when that will >> >> > happen >> >> > but if you can get away with an older CMake for now then I'd go this >> >> > way. >> >> > As you mentioned, option (1) will allow you to view your source file >> >> > structure in Android Studio, edit files, and debug using the built-in >> >> > debugging support. >> >> > >> >> > To get option (2) to work, you can use jniDirs setting to tell >> >> > Android >> >> > Gradle where to pick up your built .so files (see >> >> > >> >> > >> >> > https://stackoverflow.com/questions/21255125/how-can-i-add-so-files-to-an-android-library-project-using-gradle-0-7). >> >> > I'm not aware of any projects that use this approach but it should >> >> > work >> >> > in >> >> > principal. >> >> > >> >> > I hope this helps, >> >> > Jomo >> >> > >> >> > >> >> > On Mon, Aug 7, 2017 at 11:09 AM, Robert Dailey >> >> > <rcdailey.li...@gmail.com> >> >> > wrote: >> >> >> >> >> >> Right now I have custom targets set to execute the "ant release" >> >> >> command after my native targets are built. Part of that command >> >> >> involves copying *.so files to the libs/armeabi-v7a directory so >> >> >> they >> >> >> get packaged in an APK. >> >> >> >> >> >> When switching to gradle, I have two options: >> >> >> >> >> >> 1. Gradle drives CMake: This means using Android Studio and being >> >> >> locked down to Google's fork of CMake which is a few major releases >> >> >> behind. I see that as a negative. >> >> >> >> >> >> 2. CMake drives Gradle: This would be the same or similar to what >> >> >> I'm >> >> >> already doing: The custom targets I have would execute gradle as a >> >> >> separate build step, instead of running ant commands. I'm not too >> >> >> familiar with Gradle, so I'm not sure how you tell it where your >> >> >> shared libraries are for the APK packaging steps. >> >> >> >> >> >> Which does everyone recommend? Is anyone using one of these setups >> >> >> successfully? The downside to option 2 is probably no on-device >> >> >> native >> >> >> debugging since Android Studio probably can't handle gradle projects >> >> >> without any external CMake builds set up. >> >> >> >> >> >> Would like some general direction & advice before I move away from >> >> >> ANT. Thanks in advance. >> >> >> -- >> >> >> >> >> >> Powered by www.kitware.com >> >> >> >> >> >> Please keep messages on-topic and check the CMake FAQ at: >> >> >> http://www.cmake.org/Wiki/CMake_FAQ >> >> >> >> >> >> Kitware offers various services to support the CMake community. For >> >> >> more >> >> >> information on each offering, please visit: >> >> >> >> >> >> CMake Support: http://cmake.org/cmake/help/support.html >> >> >> CMake Consulting: http://cmake.org/cmake/help/consulting.html >> >> >> CMake Training Courses: http://cmake.org/cmake/help/training.html >> >> >> >> >> >> Visit other Kitware open-source projects at >> >> >> http://www.kitware.com/opensource/opensource.html >> >> >> >> >> >> Follow this link to subscribe/unsubscribe: >> >> >> http://public.kitware.com/mailman/listinfo/cmake >> >> > >> >> > >> > >> > > > -- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. For more information on each offering, please visit: CMake Support: http://cmake.org/cmake/help/support.html CMake Consulting: http://cmake.org/cmake/help/consulting.html CMake Training Courses: http://cmake.org/cmake/help/training.html Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Follow this link to subscribe/unsubscribe: http://public.kitware.com/mailman/listinfo/cmake
