cocos2d-js 3.0 RC0 手动绑定 C++调用js，js调用C++ jsbinding

1 JS调用C++

3.0中写这个绑定比较简单，跟ANE调用java如出一辙，一个JSContext，一个jsval，使用cocos2d提供的c++和js变量转换的函数做好转换即可。

cocos2d-js原来就定义好了代码风格：

sc->addRegisterCallback(MinXmlHttpRequest::_js_register);
sc->addRegisterCallback(register_jsb_websocket);
sc->addRegisterCallback(register_jsb_socketio);

#if (CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID)
sc->addRegisterCallback(JavascriptJavaBridge::_js_register);
#endif

sc->addRegisterCallback(register_jsb_kenko_all);

sc->start();

我们也顺着这个风格，添加一个函数：register_jsb_kenko_all，这是一个全局函数。

jsb_kenko_auto.h

#ifndef jsb_jsb_kenko_auto_h
#define jsb_jsb_kenko_auto_h

#include "cocos2d.h"

std::string os_info();
bool jsb_os_info(JSContext *cx, uint32_t argc, JS::Value *vp);
bool jsb_callback(JSContext *cx, uint32_t argc, JS::Value *vp);
void register_jsb_kenko_all(JSContext* cx, JSObject* obj);

#endif

jsb_kenko_auto.cpp

#include "jsb_kenko_auto.h"
#include "cocos2d_specifics.hpp"

std::string os_info() {
CCLOG("it's c++ os_info here");
return "os_info";
}

bool jsb_os_info(JSContext *cx, uint32_t argc, JS::Value *vp) {
jsval ret = std_string_to_jsval(cx, os_info());
JS_SET_RVAL(cx, vp, ret);

return true;
}

void register_jsb_kenko_all(JSContext *cx, JSObject *obj) {
JS_DefineFunction(cx, obj, "osInfo", jsb_os_info, 0, 0);  //生成名为osInfo的js全局函数

}

把h和cpp文件都放到AppDelegate.cpp同一个地方。上述的c++代码会在spidermonkey运行环境中生成相应的js接口，所以，我们不需要自己额外写对应的js接口。

然后就可以写js代码试试了。从运行结果可以看到，js调用成功，并获取到返回值。

cc.game.onStart = function(){
cc.view.setDesignResolutionSize(800, 450, cc.ResolutionPolicy.SHOW_ALL);
cc.view.resizeWithBrowserSize(true);
cc.director.runScene(new MainScene());

cc.log("js get from c++: " + osInfo());
};
cc.game.run();

2 C++回调

关键在于使用ScriptingCore提供的方法，调用js。首先来看看ScriptingCore的源代码，都有些什么方法可以用。

executeFunctionWithOwner可以实现类似cc.sprite之类的c++对象和js对象的调用，没有深究。这里演示的是如何做全局调用。

evalString对任何一个前端开发来说都不会太陌生，毕竟这里不是浏览器，排除各种乱七八糟的安全问题，我们直接用这个函数。

/**
@brief Execute a scripted global function.
@brief The function should not take any parameters and should return an integer.
@param functionName String object holding the name of the function, in the global script environment, that is to be executed.
@return The integer value returned from the script function.
*/
virtual int executeGlobalFunction(const char* functionName) { return 0; }

virtual int sendEvent(cocos2d::ScriptEvent* message) override;

virtual bool parseConfig(ConfigType type, const std::string& str) override;

virtual bool handleAssert(const char *msg) { return false; }

virtual void setCalledFromScript(bool callFromScript) { _callFromScript = callFromScript; };
virtual bool isCalledFromScript() { return _callFromScript; };

bool executeFunctionWithObjectData(void* nativeObj, const char *name, JSObject *obj);
bool executeFunctionWithOwner(jsval owner, const char *name, uint32_t argc = 0, jsval* vp = NULL, jsval* retVal = NULL);

void executeJSFunctionWithThisObj(jsval thisObj, jsval callback, uint32_t argc = 0, jsval* vp = NULL, jsval* retVal = NULL);

/**
* will eval the specified string
* @param string The string with the javascript code to be evaluated
* @param outVal The jsval that will hold the return value of the evaluation.
* Can be NULL.
*/
bool evalString(const char *string, jsval *outVal, const char *filename = NULL, JSContext* cx = NULL, JSObject* global = NULL);

修改jsb_kenko_auto.cpp：

#include "jsb_kenko_auto.h"
#include "cocos2d_specifics.hpp"

std::string os_info() {
CCLOG("it's c++ os_info here");
return "os_info";
}

bool jsb_callback(JSContext *cx, uint32_t argc, JS::Value *vp) {
CCLOG("it's c++ testCallback here");
JSContext* jc = ScriptingCore::getInstance()->getGlobalContext();
// 注释部分适合有对象化的调用
// 参考：http://www.tairan.com/archives/4902
//jsval v[2];
//v[0] = int32_to_jsval(jc, 32);
//v[1] = int32_to_jsval(jc, 12);

// 通过 ScriptingCore 封装好的方法实现回调，可以帮助我们节省很多细节上的研究
//js_proxy_t * p = jsb_get_native_proxy();
//return ScriptingCore::getInstance()->executeFunctionWithOwner(OBJECT_TO_JSVAL(p->obj), "cpp_callback", 2, v);        //2是参数个数，v是参数列表

//找到一个更适合全局函数的方法
jsval ret;
return ScriptingCore::getInstance()->evalString("cpp_callback(2,3)", &ret);
}

bool jsb_os_info(JSContext *cx, uint32_t argc, JS::Value *vp) {
jsval ret = std_string_to_jsval(cx, os_info());
JS_SET_RVAL(cx, vp, ret);

return true;
}

void register_jsb_kenko_all(JSContext *cx, JSObject *obj) {
JS_DefineFunction(cx, obj, "osInfo", jsb_os_info, 0, 0);
JS_DefineFunction(cx, obj, "test_cpp_callback", jsb_callback, 0, 0);
}

相应在js侧添加一个全局函数，给c++调用。

cc.game.onStart = function(){
cc.view.setDesignResolutionSize(800, 450, cc.ResolutionPolicy.SHOW_ALL);
cc.view.resizeWithBrowserSize(true);
cc.director.runScene(new MainScene());

cc.log("js get from c++: " + osInfo());
test_cpp_callback();
};
cc.game.run();

function cpp_callback(a, b) {
cc.log("cpp return two integer: " + a + " " + b);
}

看输出结果：


3 各种变量转换函数

bool jsval_to_ushort( JSContext *cx, jsval vp, unsigned short *ret );
bool jsval_to_int32( JSContext *cx, jsval vp, int32_t *ret );
bool jsval_to_uint32( JSContext *cx, jsval vp, uint32_t *ret );
bool jsval_to_uint16( JSContext *cx, jsval vp, uint16_t *ret );
bool jsval_to_long( JSContext *cx, jsval vp, long *out);
bool jsval_to_ulong( JSContext *cx, jsval vp, unsigned long *out);
bool jsval_to_long_long(JSContext *cx, jsval v, long long* ret);
bool jsval_to_std_string(JSContext *cx, jsval v, std::string* ret);

jsval int32_to_jsval( JSContext *cx, int32_t l);
jsval uint32_to_jsval( JSContext *cx, uint32_t number );
jsval ushort_to_jsval( JSContext *cx, unsigned short number );
jsval long_to_jsval( JSContext *cx, long number );
jsval ulong_to_jsval(JSContext* cx, unsigned long v);
jsval long_long_to_jsval(JSContext* cx, long long v);
jsval std_string_to_jsval(JSContext* cx, const std::string& v);

转载来源 http://www.cnblogs.com/kenkofox/p/3910462.html