Native与ArkTS对象绑定

场景介绍

通过napi_wrap将ArkTS对象与Native的C++对象绑定,后续操作时再通过napi_unwrap将ArkTS对象绑定的C++对象取出,并对其进行操作。

使用示例

  1. 接口声明、编译配置以及模块注册

    接口声明

    // index.d.ts
    export class MyObject {
       constructor(arg: number);
       plusOne: () => number;
    
       public get value();
       public set value(newVal: number);
    }
    

    编译配置

    // CMakeLists.txt
    # the minimum version of CMake.
    cmake_minimum_required(VERSION 3.4.1)
    project(object_wrap)
    
    set(NATIVERENDER_ROOT_PATH ${CMAKE_CURRENT_SOURCE_DIR})
    
    include_directories(${NATIVERENDER_ROOT_PATH}
                        ${NATIVERENDER_ROOT_PATH}/include)
    
    add_definitions("-DLOG_DOMAIN=0x0000")
    add_definitions("-DLOG_TAG=\"testTag\"")
    
    add_library(object_wrap SHARED object_wrap.cpp)
    target_link_libraries(object_wrap PUBLIC libace_napi.z.so libhilog_ndk.z.so)
    

    模块注册

    // object_wrap.cpp
    class MyObject {
     public:
      static napi_value Init(napi_env env, napi_value exports);
      static void Destructor(napi_env env, void* nativeObject, void* finalize_hint);
    
     private:
      explicit MyObject(double value_ = 0);
      ~MyObject();
    
      static napi_value New(napi_env env, napi_callback_info info);
      static napi_value GetValue(napi_env env, napi_callback_info info);
      static napi_value SetValue(napi_env env, napi_callback_info info);
      static napi_value PlusOne(napi_env env, napi_callback_info info);
    
      double value_;
      napi_env env_;
      napi_ref wrapper_;
    };
    
    static thread_local napi_ref g_ref = nullptr;
    
    MyObject::MyObject(double value)
        : value_(value), env_(nullptr), wrapper_(nullptr) {}
    
    MyObject::~MyObject()
    {
      napi_delete_reference(env_, wrapper_);
    }
    
    void MyObject::Destructor(napi_env env,
                              void* nativeObject,
                              [[maybe_unused]] void* finalize_hint)
    {
      OH_LOG_INFO(LOG_APP, "MyObject::Destructor called");
      reinterpret_cast<MyObject*>(nativeObject)->~MyObject();
    }
    
    napi_value MyObject::Init(napi_env env, napi_value exports)
    {
      napi_property_descriptor properties[] = {
          {"value", 0, 0, GetValue, SetValue, 0, napi_default, 0},
          { "plusOne", nullptr, PlusOne, nullptr, nullptr, nullptr, napi_default, nullptr }
      };
    
      napi_value cons;
      assert(napi_define_class(env, "MyObject", NAPI_AUTO_LENGTH, New, nullptr, 2,
                               properties, &cons) == napi_ok);
    
      assert(napi_create_reference(env, cons, 1, &g_ref) == napi_ok);
      assert(napi_set_named_property(env, exports, "MyObject", cons) == napi_ok);
      return exports;
    }
    
    EXTERN_C_START
    static napi_value Init(napi_env env, napi_value exports)
    {
        MyObject::Init(env, exports);
        return exports;
    }
    EXTERN_C_END
    
    static napi_module nativeModule = {
        .nm_version = 1,
        .nm_flags = 0,
        .nm_filename = nullptr,
        .nm_register_func = Init,
        .nm_modname = "object_wrap",
        .nm_priv = nullptr,
        .reserved = { 0 },
    };
    
    extern "C" __attribute__((constructor)) void RegisterObjectWrapModule()
    {
        napi_module_register(&nativeModule);
    }
    
  2. 在构造函数中绑定ArkJS与C++对象

    napi_value MyObject::New(napi_env env, napi_callback_info info)
    {
      OH_LOG_INFO(LOG_APP, "MyObject::New called");
    
      napi_value newTarget;
      assert(napi_get_new_target(env, info, &newTarget) == napi_ok);
      if (newTarget != nullptr) {
        // 使用`new MyObject(...)`调用方式
        size_t argc = 1;
        napi_value args[1];
        napi_value jsThis;
        assert(napi_get_cb_info(env, info, &argc, args, &jsThis, nullptr) == napi_ok);
    
        double value = 0.0;
        napi_valuetype valuetype;
        assert(napi_typeof(env, args[0], &valuetype) == napi_ok);
        if (valuetype != napi_undefined) {
          assert(napi_get_value_double(env, args[0], &value) == napi_ok);
        }
    
        MyObject* obj = new MyObject(value);
    
        obj->env_ = env;
        // 通过napi_wrap将ArkTS对象jsThis与C++对象obj绑定
        assert(napi_wrap(env,
                         jsThis,
                         reinterpret_cast<void*>(obj),
                         MyObject::Destructor,
                         nullptr,  // finalize_hint
                         &obj->wrapper_) == napi_ok);
    
        return jsThis;
      } else {
        // 使用`MyObject(...)`调用方式
        size_t argc = 1;
        napi_value args[1];
        assert(napi_get_cb_info(env, info, &argc, args, nullptr, nullptr) == napi_ok && argc == 1);
    
        napi_value cons;
        assert(napi_get_reference_value(env, g_ref, &cons) == napi_ok);
        napi_value instance;
        assert(napi_new_instance(env, cons, argc, args, &instance) == napi_ok);
    
        return instance;
      }
    }
    
  3. 将ArkTS对象之前绑定的C++对象取出,并对其进行操作

    napi_value MyObject::GetValue(napi_env env, napi_callback_info info)
    {
      OH_LOG_INFO(LOG_APP, "MyObject::GetValue called");
    
      napi_value jsThis;
      assert(napi_get_cb_info(env, info, nullptr, nullptr, &jsThis, nullptr) == napi_ok);
    
      MyObject* obj;
      // 通过napi_unwrap将jsThis之前绑定的C++对象取出,并对其进行操作
      assert(napi_unwrap(env, jsThis, reinterpret_cast<void**>(&obj)) == napi_ok);
      napi_value num;
      assert(napi_create_double(env, obj->value_, &num) == napi_ok);
    
      return num;
    }
    
    napi_value MyObject::SetValue(napi_env env, napi_callback_info info)
    {
      OH_LOG_INFO(LOG_APP, "MyObject::SetValue called");
    
      size_t argc = 1;
      napi_value value;
      napi_value jsThis;
    
      assert(napi_get_cb_info(env, info, &argc, &value, &jsThis, nullptr) == napi_ok);
    
      MyObject* obj;
      // 通过napi_unwrap将jsThis之前绑定的C++对象取出,并对其进行操作
      assert(napi_unwrap(env, jsThis, reinterpret_cast<void**>(&obj)) == napi_ok);
      assert(napi_get_value_double(env, value, &obj->value_) == napi_ok);
    
      return nullptr;
    }
    
    napi_value MyObject::PlusOne(napi_env env, napi_callback_info info)
    {
      OH_LOG_INFO(LOG_APP, "MyObject::PlusOne called");
    
      napi_value jsThis;
      assert(napi_get_cb_info(env, info, nullptr, nullptr, &jsThis, nullptr) == napi_ok);
    
      MyObject* obj;
      // 通过napi_unwrap将jsThis之前绑定的C++对象取出,并对其进行操作
      assert(napi_unwrap(env, jsThis, reinterpret_cast<void**>(&obj)) == napi_ok);
      obj->value_ += 1;
      napi_value num;
      assert(napi_create_double(env, obj->value_, &num) == napi_ok);
    
      return num;
    }
    
  4. ArkTS侧示例代码

    import hilog from '@ohos.hilog';
    import { MyObject } from 'libobject_wrap.so'
    
    let object : MyObject = new MyObject(0);
    object.value = 1023;
    hilog.info(0x0000, 'testTag', 'MyObject value after set: %{public}d', object.value);
    hilog.info(0x0000, 'testTag', 'MyObject plusOne: %{public}d', object.plusOne());