A simple crossplatform SDL2 + skia CMake build environment example/test. Based on simpleSDL (thank you so much!).

Tested to build and run successfully with:

• Linux (Ubuntu): Clang
• Android: Gradle + NDK
• Windows: mingw-w64 or Visual Studio 2015

Table of contents:

1. Getting started
   1. Requirements
   2. Clone
   3. Preparing skia
2. Compilling
   1. Linux
   2. Android
   3. Windows
3. Contributing

The standard skia build does not have CMake compatibility so we will transform the build. Learn more about the skia build.

Step-by-step:

1. Run python2 tools/git-sync-deps inside externals;

2. Generate CMake project:

   bin/gn gen out/cmake --ide=json --json-ide-script=../../gn/gn_to_cmake.py --args='is_official_build=true'
   

   to build skia as a static library or

   bin/gn gen out/cmake --ide=json --json-ide-script=../../gn/gn_to_cmake.py --args='is_official_build=true is_component_build=true'
   

   to build skia as a dynamic library. To see all available arguments:

   bin/gn args out/cmake --list
   

   suggestion for Android build:

   bin/gn gen out/cmake --ide=json --json-ide-script=../../gn/gn_to_cmake.py --args='
            skia_use_system_libjpeg_turbo = false
            skia_use_system_libwebp = false
            skia_use_system_expat = false
            skia_use_system_libpng = false
            skia_use_system_freetype2 = false
            ndk="/home/you/Android/Sdk/ndk/21.3.6528147"
            target_os="android" 
            target_cpu="arm"
            is_debug=false
            is_component_build=true
            extra_cflags=["-O3"]
            skia_use_angle = false
            skia_use_icu = false
            skia_use_lua = false
            skia_use_opencl = false
            skia_use_piex = false
            skia_use_zlib = false
            skia_enable_tools = false
            skia_enable_pdf = false
            skia_use_gl = true
            skia_enable_skottie = false
            '
   

Just run build.sh inside platforms folder.

Alternatively you can do something like this in the project root dir:

mkdir build/make_debug
cd build/make_debug
cmake -DCMAKE_BUILD_TYPE:STRING=Debug ../..
make

Make sure you have NDK and CMake plugins installed on Android SDK (https://developer.android.com/studio/projects/add-native-code.html).

Step-by-step:

1. Make sure you have installed:

   1. Android SDK Build Tools 30;
   2. NDK 21;
   3. Android CMake 10.

2. Have the ANDROID_HOME environment variable;

3. Copy all content from

   externals/SDL/android-project/app/src/main/java/org/libsdl/app
   

   and put it into

   platforms/android/android-app/src/main/java/org/libsdl/app/
   

4. Pay attention to the skia build and see if all the arguments are in the arg.gn file. See build options here.

5. Run gradlew assemble in platforms/android

   or

   Open the project in Android Studio and build using the IDE. NOTE: Make sure to open the platforms/android/ dir. Android studio can also open the root dir but it's not recognized as an android project.

The included Android Gradle CMake project is pretty much what Android Studio generates when you create a new empty app with native CMake support. Just pointing to the CMakeLists.txt in the project root.