v8学习笔记(八) 【JS与C++互调】

v8中JS与C++互调

**************************v8中JS调C++:注册回调函数*****************************

 

JS调C++数据:访问器(Accessor)  (直接访问)

(1)定义C++回调函数Getter/Setter

(2)Context全局对象模板(ObjectTemplate)注册Getter/Setter

 

 

 

JS调C++函数:(Context)全局对象模板ObjectTemplate注册回调函数(通过v8::Arguments传递参数)

        Template::Set(Handle<String> name, Handle<Data> value,PropertyAttribute attributes = None);

 

 

JS调C++对象:(通过CPPObj.XXX访问)

1.C++对象映射成(v8_API)JS对象,加入JS运行时环境(Context):                                        C++类映射成ObjectTemplate对象

                  (1)创建JS对象模板ObjectTemplate:   

                                    Handle<ObjectTemplate> JSObjTempl = ObjectTemplate::New();

                  (2)设置对象模板内部域:                

                                    JSObjTempl->SetInternalFieldCount(1);

                  (3)创建JS对象:

                                    Local<Object> JSObj=JSObjTempl->NewInstance();

                  (3)C++对象包装成(External)外部对象,放入JS对象内部域:       

                                    ClassA* p=new ClassA(3,7);

                                    Local<External> Ext=External::New(p);

                                    JSObj->SetInternalField(0,Ext);

                  (4)JS对象放入运行时环境(全局对象) 

                                    context->Global()->Set(String::New("ClassA"),JSObj);

                                    

2.调C++对象的成员数据:JS对象模板注册Getter/Setter回调函数

                  JSObjTempl->SetAccessor(String::New("x"),GetCPPObj_X,SetCPPObj_X);

                  JSObjTempl->SetAccessor(String::New("y"),GetCPPObj_Y,SetCPPObj_Y);

3.调C++对象的成员函数:JS对象模板注册回调函数,通过回调函数调用成员函数

                  JSObjTempl->Set(String::New("method_a"), FunctionTemplate::New(Callback_A));

                  JSObjTempl->Set(String::New("method_b"), FunctionTemplate::New(Callback_B));

 

                  

回调函数:(1)(当前调用)JS对象:

                           Local<Object> self = AccessorInfo.Holder()/Arguments.Holder();

                   (2)(包装后)外部对象:

                           Local<External> wrap = Local<External>::Cast(self->GetInternalField(0));

                   (3)C++对象                      

                           CPPObj* p = static_cast<CPPObj*>(wrap->Value())

**********************************C++调JS**************************************

                  

C++调JS函数:运行时环境查找JS函数,并调用