I am working on an Android application with NDK. My c++ code has some dependencies from c++ open source libraries, so I can download the source code of the dependencies and package them in my app. I have created my CMakeList files, but I don't know how to include the external library.
I would like to build the dependency to be able to use it in my own project, so the flow would be as follows:
cd external/library/path
./configure
make
build my app and link the built dependency
Is this possible? If so, how can this be done? Sorry if this is a dumb question, I'm new on C++ and Cmake.
The way I solved this was by cross compiling the libraries and adding them as static libraries. You can cross compile using the clang binaries included in the ndk directory, using the one that targets your app min sdk.
Related
I have editted parts of the zlib-1.2.13 library to add additional functionality.
I would like to compile this library and produce a static library that I can link to as part of an android app.
I am struggling to use CMAKE to compile the static library for the correct architecture.
My question is, how do I compile and generate a static library that I can link to as part of an android app?
I saw a similar question on here that led me to try compile the library using the following command, 'CC=gcc CHOST=arm64 ./configure', then 'sudo make' on my linux VM however the static library generated appears to still be for the linux architecture.
As well as this, when I try to run the CMAKE directly through android studio, pointing the build.gradle file directly at the zlib CMAKELists.txt file directly no libraries are generated.
Any help would be greatly appreciated! :)
I have an android project that currently uses Cmake for including all .cpp /.c code. Now I want to add the GStreamer native libraries such that I can use them in my native code.
But the gstreamer docs https://gstreamer.freedesktop.org/documentation/installing/for-android-development.html
only document using ndk-build to use gstreamer on android.
Now I don't want to totally refactor my project to use ndk-build and Android.mk because
CMake does its job and i never had problems with it
as stated here cmake is the default for android ndk https://developer.android.com/studio/projects/add-native-code
I also need to include the googlevr ndk library that uses cmake.
So I need to figure out a workaround and therefore need your help. Here are some ideas I came up with
Each module can have ether cmake or ndk-build support. Therefore,
I probably could add a new module using ndk-build and include gstreamer there (but then gstreamer is only available in this module)
Compile gstreamer for android using cmake inside android studio - but I don't see evidence that has been done before or is possible for someone without strong cmake knowledge.
Any other ideas/ improvements ? thanks
Even though you have already moved away from GStreamer but in case someone else is facing this issue please have a look at following github repository
https://github.com/henkeldi/gstreamer-android
For myself, I had to make two modifications
I modified the definition of GSTREAMER_ROOT to include ANDROID_ABI so it looks like following
#GStreamer
set(GSTREAMER_ROOT $ENV{GSTREAMER_ROOT_ANDROID}/${ANDROID_ABI})
I had to rename the folders in GStreamer pre-built binaries to be according to ANDROID_ABI. So, my Gstreamer pre-built binaries folder look like following
After the above changes, I am able to successfully build with APK with GStreamer using CMake
At some point I gave up on gstreamer and am now using ffmpeg instead.
There is a nice tutorial for compiling ffmpeg that makes including native ffmpeg inside an android project really easy:
Tutorial on Medium
Github project
I would like to download some working example of Android Studio NDK project with C or C++ which will be compiled to .so library (or APK from which I can extract .so).
I have tried ndkbuild with Android.mk build and also CMake with CMakeLists.txt, official and unofficial tutorials on Windows...
If I try them on android from same app (java), it is working but I want to use NDK in Unity3D on android and I keep getting DllNotFoundException.
I uploaded my Android and Unity projects to github.
First of all, here is a sample Android Project plugin you are looking for.
It's very important to know how to do this yourself.
This used to be hard to do before but the latest Android Studio made it easier to now use C/C++ or generate .so library easily. Update Android Studio to the latest version then follow steps below to create a C++ plugin.
1.Create a new Project in Android Studio
2.Check the Include C++ suport to enable C++.
3.On the Dropdown Menu, check C++ 11 on the C++ Standard drop-down menu. You will need C++ 11 to actually use most useful C++ features. Also, enable exception or frtti if you need them.
That's really it.
When you build the plugin:
The debug library is should be at:
\app\build\intermediates\cmake\debug\obj\
The release library is should be at:
\app\build\intermediates\cmake\debug\obj\
If you only see the debug but not the release version of the plugin, check here for how to make it appear.
Possible reasons you are getting DllNotFoundException on Android:
1.You did not wrap the C/C++ function around extern "C". You must do this for each function in the .cpp file or you do it in the function in the .h file.
2.You put the plugin in the wrong Unity folder.
The armeabi-v7a and x86 plugins generated at <ProjectDirectory>\app\build\intermediates\cmake\release\obj should be placed at Assets\Plugins\Android\libs\armeabi-v7a\ and Assets\Plugins\Android\libs\x86\ in the Unity project.
Make sure to spell these correctly. See this for more information about this.
3.You are loading it incorrectly from the C# side.
Let's say that the name of the plugin is libScreenshot.a, do not include the lib prefix, also do not add the .a when loading it.
[DllImport("Screenshot", CallingConvention = CallingConvention.Cdecl)]
public static extern void takeScreenshot();
Basically, I want to know how to use a c++ shared library in Android Studio in NDK code (inside jni part). There is quite a lot of questions about that but they all are based on changing Android.mk which is not a way to go because in AS it's generated automatically.
To use pre built librairies with Android Studio, you have to follow these steps:
Compile your C++ librarie with ndk-build (here you build librairies for Android architecture such like arm, x86, etc.).
Create a Java class and JNI wrapper for your C++ methods.
You have then to disable gradle for ndk-build and create your own Android.mk and Application.mk in the jni folder.
Import the .so library and pre build it in the Android.mk.
Invoke ndk-build manually, from the Android Studio console.
Then, include the header of your librarie and call its functions in your JNI part.
For any complement of information, I advise you the intel video that you can find here.
I want to cross compile a c++ library to the android plateform and this library depends on other libraries (those librairies are included yet in the android plateform).
Actually ,i have downloaded the android source code (android 4.1), i have also the library source code and i just don't know how to cross compile this library with it dependencies?
I would be thankfull if someone can tell me the right way to do it.
I believe that the easiest path is to set up the standalone toolchain using latest Android NDK, and build your library and all its dependencies with that toolchain. Here is an example: http://trac.osgeo.org/gdal/wiki/BuildingForAndroid