We start by pointing pApp->onAppCmd to our message loop so that system messages have somewhere to go. This is called by android_native_app_glue when your application starts up. Any touch events, window events, &c will come through here. This will serve as our message loop in the future. I’m creating a small placeholder function handle_cmd. You can still write C++ code inside of there, but the functions will look like C functions to the rest of our program. Then I look for the automatically generated environment variable $, we’re just telling the linker that we need to treat everything between those curly braces as C. First I add_library to create a library called native_app_glue and denote it as a STATIC library. There’s a lot to break down here, so lets start. Setup your IDEįirst we need to make sure that you have everything installed for native development. You may opt instead to use a library like SDL or even Google’s FPLBase instead. I recommend reading through the samples Google provides, although I will provide some tips to make your life easier. I will stop short of showing you how to initialize a Vulkan or OpenGL context. You may find that despite C’s cognitive overhead, some common code challenges like building vertex attribute arrays from game data become easier in C++ than higher level languages. In fact, the native activity I’ll be showing you provides an easy one-stop shop in which you can set up an OpenGL canvas and start gathering user input. If you want to make a game from scratch or port over an existing game, Android’s Native Development Kit (or NDK) and its supporting tooling are ready and waiting. When you also consider that C and C++ are near universal to every computing platform, and the relative wealth of C libraries to support games development, it may become reasonable to set off down the path of native development. Since games typically use custom rendering logic, often written in OpenGL or Vulkan, it’s expected that a game looks different from a standard Android application. Near and dear to my own heart is game development. For most applications, you’re better off with languages like Kotlin. Counter intuitively, you are in some ways writing a foreign application with only a subset of Android features available. Many core Android system features, such as the Android UI and Intent handling, are only exposed through Java interfaces.īy choosing to use C++, you are not being “more native” to Android than using a managed language such as Kotlin or Java. Applications written in these languages benefit from tooling embedded deep into the system’s underlying architecture. On Android, the OS and its supporting infrastructure are designed to support applications written in the Java or Kotlin programming languages. That is a discussion that literally fills up books. I will walk through the basic setup, and try to give you the tools you need to move forward.Īlthough my focus is on games, I will not be telling you how to write an OpenGL application or how to architect your own game engine. I would like to walk you through setting up a simple Android Native Activity. Getting started with C++ and Android Native Activities Introduction Files placed in Classes folder are automatically compiled by the Xcode build system therefore we don’t need to specify them explicitly. podspec file, though it’s not a problem for Android build system. Your C code has to be placed inside of plugin’s ios/Classes folder because CocoaPods doesn’t allow including source code from anywhere above. If your library doesn’t provide shared libraries, you have to link it statically and use C++ static runtime. podspec file: # telling CocoaPods not to remove framework s.preserve_paths = ‘amework’ # telling linker to include opencv2 framework s.xcconfig = Place the framework in plugin’s ios folder (or use a symbolic link) and add lines to. OpenCV also requires AVFoundation framework. OpenCV is distributed as a framework and it has to be included in the plugin along with C++ library. Next, we need to update the app’s dependency list in pubspec.yaml with a newly created plugin and ffi package: dependencies: native_opencv: path: native_opencv ffi: ^0.1.3įfi package comes in handy for working with C UTF-8/UTF-16 strings. Run flutter create - template=plugin native_opencv command to create it. Creating a pluginĮven though it’s not required, it’s better to create a Flutter plugin to separate all task-specific stuff from the main application. OpenCV is a computer vision library that contains a lot of services used for image processing. That leads to having a single code base written in C with zero platform-specific code. Dart Foreign Function Interface (FFI) allows us to call native C/C++ functions on both iOS and Android platforms without using Platform Channels or making Java/Objective-C bindings.
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