Android is not officialy supported, and there are no official android triplets at the moment.
However, some packages can compile to Android, and the situation is improving: see the list of [PR related to Android](https://github.com/Microsoft/vcpkg/pulls?q=+android+).
## Android build requirements
1. Download the [android ndk](https://developer.android.com/ndk/downloads/)
2. Set environment variable `ANDROID_NDK_HOME` to your android ndk installation.
Vcpkg has a [`vulkan` package](https://github.com/microsoft/vcpkg/blob/master/ports/vulkan/portfile.cmake) which allows you to `find_package(Vulkan)`. To use it you have to provide `VULKAN_SDK` environment variable.
```bash
export VULKAN_SDK=/usr/local
./vcpkg install vulkan
```
NDK already contains [Vulkan](https://developer.android.com/ndk/guides/graphics/getting-started) headers and `libvulkan.so` binaries for each of its architecture.
To expose them to VcPkg, you can consider `export VULKAN_SDK=...` for each installation.
But by placing `set(ENV{VULKAN_SDK} ...)` in the triplet files, you can skip the tedious work.
If you are using NDK 21.3.6528147 or earlier version, it will be like the following.
```cmake
# In android triplets... (e.g. arm64-android.cmake)
set(VCPKG_CMAKE_SYSTEM_NAME Android)
# ...
# If your API level is 30, libvulkan.so is at $ENV{ANDROID_NDK_HOME}/platforms/android-30/arch-arm64/usr/lib
Notice that **the location of the sysroot has changed since NDK 22**. (see https://github.com/android/ndk/issues/1407)
If you prefer using [the latest version](https://developer.android.com/studio/projects/install-ndk#default-ndk-per-agp), check the [BuildSystemMaintainers.md of the NDK document](https://android.googlesource.com/platform/ndk/+/master/docs/BuildSystemMaintainers.md#sysroot) and then put appropriate path for your system.
For example, Mac OS users will use the path like this.
```cmake
# In android triplets... (e.g. arm64-android.cmake)
set(VCPKG_CMAKE_SYSTEM_NAME Android)
# ...
# If your API level is 30, libvulkan.so is at $ENV{ANDROID_NDK_HOME}/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/lib/aarch64-linux-android/30
When compiling for android, you need to select a matching "android abi" / "vcpkg triplet" pair.
For example:
````bash
android_abi=armeabi-v7a
vcpkg_target_triplet=arm-android
cmake
...
-DVCPKG_TARGET_TRIPLET=$vcpkg_target_triplet \
-DANDROID_ABI=$android_abi
````
### Test on an example
The folder [docs/examples/vcpkg_android_example_cmake](../examples/vcpkg_android_example_cmake) provides a working example, with an android library that consumes the jsoncpp library:
*Details*
* The [CMakeLists](../examples/vcpkg_android_example_cmake/CMakeLists.txt) simply uses `find_package` and `target_link_library`
* The [compile.sh](../examples/vcpkg_android_example_cmake/compile.sh) script enables you to select any matching pair of "android abi" / "vcpkg triplet" and to test the compilation
* The dummy [my_lib.cpp](../examples/vcpkg_android_example_cmake/my_lib.cpp) file uses the jsoncpp library
*Note*: this example only compiles an Android library, as the compilation of a full fledged Android App is beyond the scope of this document.
### Test on an example, using [vcpkg_android.cmake](../examples/vcpkg_android_example_cmake_script/cmake/vcpkg_android.cmake)
The folder [docs/examples/vcpkg_android_example_cmake_script](../examples/vcpkg_android_example_cmake_script) provides the same example, and uses a cmake script in order to simplify the usage.
*Details*
* The main [CMakeLists](../examples/vcpkg_android_example_cmake_script/CMakeLists.txt) loads [vcpkg_android.cmake](../examples/vcpkg_android_example_cmake_script/cmake/vcpkg_android.cmake) if the flag `VCPKG_TARGET_ANDROID` is set:
````cmake
if (VCPKG_TARGET_ANDROID)
include("cmake/vcpkg_android.cmake")
endif()
````
*Important: place these lines before calling project() !*
* The [compile.sh](../examples/vcpkg_android_example_cmake_script/compile.sh) script shows that it is then possible to compile for android using a simple cmake invocation, for example:
