Flutter FFI: Integrating Native C/C++ Libraries

Flutter provides a Foreign Function Interface (FFI) called dart:ffi that allows Dart applications to call native C APIs and work with native memory. The FFI binding architecture is structured as follows: Flutter UI → Dart API → FFI binding → C ABI → C/C++ library. Direct exposure of native implementation details to widgets is discouraged.

To integrate a native C function, first create a native library file (e.g., native_math.h and native_math.c). The header file should declare the function signature, while the implementation file provides the actual function body. The extern "C" boundary is crucial when the header is consumed by C++ to prevent C++ name mangling for the exported C ABI.

In Dart, load the library using DynamicLibrary.open() and specify the appropriate library name for each platform (e.g., libnative_math.so for Android, libnative_math.so for Linux, native_math.dll for Windows, and libnative_math.dylib for macOS). Define native function types in Dart using typedefs, such as NativeAdd for the C function add_numbers(int a, int b). Dart-facing functions should be declared as DartAdd for int Function(int, int,).

Look up the symbol using the library instance and call it with the desired arguments. For example, final result = add(10, 20) would return 30. To avoid exposing raw FFI objects in the Flutter application, create a Dart wrapper class like NativeMath. This wrapper class should handle opening the library and looking up the symbol, while the application can simply use the wrapper to call the native function without needing to know the underlying implementation details.