Customized calculations (C++)
Only in advanced cases.
In special cases where you will need maximum performance or some functionality is missing from the library, you can easily create your own code in C++ and run it from JS code.
As the code can be written in C++, the solution will be fully cross-platform and does not need different implementations for iOS and Android.
In file cpp/react-native-fast-opencv.cpp find this lines:
/// ...
} else if (propName == "clearBuffers") {
return jsi::Function::createFromHostFunction(
runtime, jsi::PropNameID::forAscii(runtime, "clearBuffers"), 1,
[=](jsi::Runtime& runtime, const jsi::Value& thisValue, const jsi::Value* arguments,
size_t count) -> jsi::Value {
FOCV_Storage::clear();
return true;
});
}
return jsi::HostObject::get(runtime, propNameId);
}
// ...Add your own else check with your own customized name of function:
else if (propName == "customFunction") {
return jsi::Function::createFromHostFunction(
runtime, jsi::PropNameID::forAscii(runtime, "clearBuffers"), 1,
[=](jsi::Runtime& runtime, const jsi::Value& thisValue, const jsi::Value* arguments,
size_t count) -> jsi::Value {
// Params
FOCV_FunctionArguments args(runtime, arguments);
// Example – first param is string
auto param1 = args.asString(0);
// Second param is Mat
auto functionName = args.asMatPtr(1);
// etc
// Calculations...
// HERE OpenCV functions and API is available
// Check how to get parameters from function
// Examples in FOCV_Function.cpp
// return JSI data or just do something...
});
}Compile et voilà – you can use it in your JS code:
OpenCV.customFunction(params);