CefV8Value类实现定JavaScript数据类型、数组、对象

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3.2     CefV8Value类实现定JavaScript数据类型

3.2.1     一般对象

3.2.2     CEF实现带access的JavaScript对象

3.2.3     CEF实现带拦截器CefV8Interceptor的JavaScript对象

3.2  CefV8Value类实现定JavaScript数据类型

上面的实例中我们已经用到CefV8Value类的CreateString("My Value!")创建字符串和CreateFunction创建了函数。这个类还可以创建, null, bool, int, double, date string等数据类型，都有对应的函数。static CefRefPtr CreateArray(int length)创建JavaScript数组。下面详细讲解下给JavaScript提供创建对象。accessor就是给JavaScript提供调用的set和get方法设置或获取属性。interceptor是拦截器，拦截set和get方法。

///

  // Create a new CefV8Value object of type object with optional accessor and/or

  // interceptor. This method should only be called from within the scope of a

  // CefRenderProcessHandler, CefV8Handler or CefV8Accessor callback, or in

  // combination with calling Enter() and Exit() on a stored CefV8Context

  // reference.

  ///

  /*--cef(optional_param=accessor, optional_param=interceptor)--*/

  static CefRefPtr CreateObject(

      CefRefPtr accessor,

      CefRefPtr interceptor);

3.2.1         一般对象

如果不需要给JavaScript提供get和set方法，可以直接创建对象。

CefRefPtr obj = CefV8Value::CreateObject(NULL);

给对象设置属性名称为myval，属性值为My String;字符串类型。

virtual bool SetValue(int index, CefRefPtr value) = 0;

obj->SetValue("myval", CefV8Value::CreateString("My String!"));

3.2.2         CEF实现带access的JavaScript对象

如果要提供set和get方法，需要提供access实现类。

（1）实现access类

class MyV8Accessor : public CefV8Accessor {

public:

  MyV8Accessor() {}

  virtual bool Get(const CefString& name,

                   const CefRefPtrCefV8Value> object,

                   CefRefPtrCefV8Value>& retval,

                   CefString& exception) OVERRIDE {

    if (name == "myval") {

      // Return the value.

      retval = CefV8Value::CreateString(myval_);

      return true;

    }

    // Value does not exist.

    return false;

  }

  virtual bool Set(const CefString& name,

                   const CefRefPtrCefV8Value> object,

                   const CefRefPtrCefV8Value> value,

                   CefString& exception) OVERRIDE {

    if (name == "myval") {

      if (value->IsString()) {

        // Store the value.

        myval_ = value->GetStringValue();

      } else {

        // Throw an exception.

        exception = "Invalid value type";

      }

      return true;

    }

    // Value does not exist.

    return false;

  }

  // Variable used for storing the value.

  CefString myval_;

  // Provide the reference counting implementation for this class.

  IMPLEMENT_REFCOUNTING(MyV8Accessor);

};

（2）使用SetValue函数设置对象属性采用access方式设置和获取数据。把对象设置到窗口对象中。

virtual bool SetValue(const CefString& key,

                        AccessControl settings,

                        PropertyAttribute attribute) = 0;

typedef enum {

  V8_ACCESS_CONTROL_DEFAULT = 0,

  V8_ACCESS_CONTROL_ALL_CAN_READ = 1,

  V8_ACCESS_CONTROL_ALL_CAN_WRITE = 1

  V8_ACCESS_CONTROL_PROHIBITS_OVERWRITING = 1

} cef_v8_accesscontrol_t;

 

///

// V8 property attribute values.

///

typedef enum {

  V8_PROPERTY_ATTRIBUTE_NONE = 0,            // Writeable, Enumerable,

                                             //   Configurable

  V8_PROPERTY_ATTRIBUTE_READONLY = 1

  V8_PROPERTY_ATTRIBUTE_DONTENUM = 1

  V8_PROPERTY_ATTRIBUTE_DONTDELETE = 1

} cef_v8_propertyattribute_t;

 

obj->SetValue("myval", V8_ACCESS_CONTROL_DEFAULT,

V8_PROPERTY_ATTRIBUTE_NONE);

（3）JavaScript中调用set和get方法，就可以设置和获取属性值。

3.2.3         CEF实现带拦截器CefV8Interceptor的JavaScript对象

拦截器CefV8Interceptor和Access的区别是，除了可以用字符串来映射属性，还可以用index索引来映射属性。其定义如下

// Interface that should be implemented to handle V8 interceptor calls. The

// methods of this class will be called on the thread associated with the V8

// interceptor. Interceptor‘s named property handlers (with first argument of

// type CefString) are called when object is indexed by string. Indexed property

// handlers (with first argument of type int) are called when object is indexed

// by integer.

///

/*--cef(source=client,no_debugct_check)--*/

class CefV8Interceptor : public virtual CefBaseRefCounted {

 public:

  ///

  // Handle retrieval of the interceptor value identified by |name|. |object| is

  // the receiver (‘this‘ object) of the interceptor. If retrieval succeeds, set

  // |retval| to the return value. If the requested value does not exist, don‘t

  // set either |retval| or |exception|. If retrieval fails, set |exception| to

  // the exception that will be thrown. If the property has an associated

  // accessor, it will be called only if you don‘t set |retval|.

  // Return true if interceptor retrieval was handled, false otherwise.

  ///

  /*--cef(capi_name=get_byname)--*/

  virtual bool Get(const CefString& name,

                   const CefRefPtr object,

                   CefRefPtr& retval,

                   CefString& exception) = 0;

 

  ///

  // Handle retrieval of the interceptor value identified by |index|. |object|

  // is the receiver (‘this‘ object) of the interceptor. If retrieval succeeds,

  // set |retval| to the return value. If the requested value does not exist,

  // don‘t set either |retval| or |exception|. If retrieval fails, set

  // |exception| to the exception that will be thrown.

  // Return true if interceptor retrieval was handled, false otherwise.

  ///

  /*--cef(capi_name=get_byindex,index_param=index)--*/

  virtual bool Get(int index,

                   const CefRefPtr object,

                   CefRefPtr& retval,

                   CefString& exception) = 0;

 

  ///

  // Handle assignment of the interceptor value identified by |name|. |object|

  // is the receiver (‘this‘ object) of the interceptor. |value| is the new

  // value being assigned to the interceptor. If assignment fails, set

  // |exception| to the exception that will be thrown. This setter will always

  // be called, even when the property has an associated accessor.

  // Return true if interceptor assignment was handled, false otherwise.

  ///

  /*--cef(capi_name=set_byname)--*/

  virtual bool Set(const CefString& name,

                   const CefRefPtr object,

                   const CefRefPtr value,

                   CefString& exception) = 0;

 

  ///

  // Handle assignment of the interceptor value identified by |index|. |object|

  // is the receiver (‘this‘ object) of the interceptor. |value| is the new

  // value being assigned to the interceptor. If assignment fails, set

  // |exception| to the exception that will be thrown.

  // Return true if interceptor assignment was handled, false otherwise.

  ///

  /*--cef(capi_name=set_byindex,index_param=index)--*/

  virtual bool Set(int index,

                   const CefRefPtr object,

                   const CefRefPtr value,

                   CefString& exception) = 0;

};

实例步骤如下

（1）实现Interceptor类

class Interceptor : public CefV8Interceptor {

   public:

    Interceptor() {}

    virtual bool Get(const CefString& name,

                     const CefRefPtr object,

                     CefRefPtr& retval,

                     CefString& exception) OVERRIDE {

      return true;

    }

    virtual bool Get(int index,

                     const CefRefPtr object,

                     CefRefPtr& retval,

                     CefString& exception) OVERRIDE {

      return true;

    }

    virtual bool Set(const CefString& name,

                     const CefRefPtr object,

                     const CefRefPtr value,

                     CefString& exception) OVERRIDE {

      return true;

    }

    virtual bool Set(int index,

                     const CefRefPtr object,

                     const CefRefPtr value,

                     CefString& exception) OVERRIDE {

      return true;

    }

    IMPLEMENT_REFCOUNTING(Interceptor);

  };

（2）创建Interceptor对象和JavaScript对象

  CefRefPtr interceptor = new Interceptor();

  PERF_ITERATIONS_START()

  CefRefPtr value = CefV8Value::CreateObject(nullptr, interceptor);

（3）SetValue（）函设置到窗口对象中（待验证）

（4）JavaScript调用按照字符串名称或者索引来设置获取值。

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CefV8Value类实现定JavaScript数据类型、数组、对象

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原文地址：https://www.cnblogs.com/bclshuai/p/12738953.html