Cocos2dx-jsb 中Node的onEnter过程分析(1)

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Cocos2dx-jsb 中Node的onEnter过程分析(1)：
1、
当一个子节点被接入到父节点上时，都会调用Node::addChild方法，
if( _running ){child->onEnter(); //调用子节点的onEnter方法// prevent onEnterTransitionDidFinish to be called twice when a node is added in onEnterif (_isTransitionFinished) //如果有场景又过度，则调用onEnterTransitionDidFinish方法，和上面的onEnter方法类似。{child->onEnterTransitionDidFinish();}}
2、
onEnter方法分析：
void Node::onEnter()
{if (_onEnterCallback) //如果有回到，则调用_onEnterCallback();○1#if CC_ENABLE_SCRIPT_BINDING  //如果绑定了脚本，则调用if (_scriptType == kScriptTypeJavascript){○2 if (ScriptEngineManager::sendNodeEventToJS(this, kNodeOnEnter))return;}
#endif○3 _isTransitionFinished = false;for( const auto &child: _children)child->onEnter();this->resume();_running = true;#if CC_ENABLE_SCRIPT_BINDINGif (_scriptType == kScriptTypeLua){ScriptEngineManager::sendNodeEventToLua(this, kNodeOnEnter);}
#endif
}3、
看函数的名字，发送节点事件给JS
ScriptEngineManager::sendNodeEventToJS(this, kNodeOnEnter)
bool ScriptEngineManager::sendNodeEventToJS(Node* node, int action)
{auto scriptEngine = getInstance()->getScriptEngine();//这里是为了防止反复调用，标记是不是从JS调用的if (scriptEngine->isCalledFromScript()){// Should only be invoked at root class NodescriptEngine->setCalledFromScript(false);}else{BasicScriptData data(node,(void*)&action);ScriptEvent scriptEvent(kNodeEvent,(void*)&data);if (scriptEngine->sendEvent(&scriptEvent))return true;}return false;
}
4、sendEvent： 
int ScriptingCore::sendEvent(ScriptEvent* evt)
{if (NULL == evt)return 0;// special type, can't use this code after JSAutoCompartmentif (evt->type == kRestartGame){restartVM();return 0;}JSAutoCompartment ac(_cx, _global.ref().get());
//这里会根据事件的类型调用不同的函数，我们这里的是kNodeEvent事件，
//我们这次只分析这个switch (evt->type){case kNodeEvent:{return handleNodeEvent(evt->data);}break;case kMenuClickedEvent:break;case kTouchEvent:{TouchScriptData* data = (TouchScriptData*)evt->data;return handleTouchEvent(data->nativeObject, data->actionType, data->touch, data->event);}break;case kTouchesEvent:{TouchesScriptData* data = (TouchesScriptData*)evt->data;return handleTouchesEvent(data->nativeObject, data->actionType, data->touches, data->event);}break;case kComponentEvent:{return handleComponentEvent(evt->data);}break;default:CCASSERT(false, "Invalid script event.");break;}return 0;
}5、handleNodeEvent这个函数是真正的调用Js
int ScriptingCore::handleNodeEvent(void* data)
{if (NULL == data)return 0;BasicScriptData* basicScriptData = static_cast<BasicScriptData*>(data);if (NULL == basicScriptData->nativeObject || NULL == basicScriptData->value)return 0;Node* node = static_cast<Node*>(basicScriptData->nativeObject);int action = *((int*)(basicScriptData->value));js_proxy_t * p = jsb_get_native_proxy(node);if (!p) return 0;int ret = 0;JS::RootedValue retval(_cx);jsval dataVal = INT_TO_JSVAL(1);if (action == kNodeOnEnter)
{
//根据不同的事件，如果JS又重载，调用不同的JS重载函数。if (isFunctionOverridedInJS(JS::RootedObject(_cx, p->obj.get()), "onEnter", js_cocos2dx_Node_onEnter)){ret = executeFunctionWithOwner(OBJECT_TO_JSVAL(p->obj), "onEnter", 1, &dataVal, &retval);}resumeSchedulesAndActions(p);}else if (action == kNodeOnExit){if (isFunctionOverridedInJS(JS::RootedObject(_cx, p->obj.get()), "onExit", js_cocos2dx_Node_onExit)){ret = executeFunctionWithOwner(OBJECT_TO_JSVAL(p->obj), "onExit", 1, &dataVal, &retval);}pauseSchedulesAndActions(p);}else if (action == kNodeOnEnterTransitionDidFinish){if (isFunctionOverridedInJS(JS::RootedObject(_cx, p->obj.get()), "onEnterTransitionDidFinish", js_cocos2dx_Node_onEnterTransitionDidFinish)){ret = executeFunctionWithOwner(OBJECT_TO_JSVAL(p->obj), "onEnterTransitionDidFinish", 1, &dataVal, &retval);}}else if (action == kNodeOnExitTransitionDidStart){if (isFunctionOverridedInJS(JS::RootedObject(_cx, p->obj.get()), "onExitTransitionDidStart", js_cocos2dx_Node_onExitTransitionDidStart)){ret = executeFunctionWithOwner(OBJECT_TO_JSVAL(p->obj), "onExitTransitionDidStart", 1, &dataVal, &retval);}}else if (action == kNodeOnCleanup) {cleanupSchedulesAndActions(p);}return ret;
}6、到此为止，○1○2两部分都分析完了，那第○3部分，什么时候调用呢？
第三部分的代码：_isTransitionFinished = false;for( const auto &child: _children)child->onEnter();this->resume();_running = true;
第三部分的其实是在JS中重载的onEnter函数：其实也就是我们的onEnter调用过程的测试代码：
onEnter : function (){cc.log("onEnter+++++++++++++++++++++++++1111111")this._super(); // 第○3部分是在这里调用的,下一篇再进行分析。cc.log("onEnter+++++++++++++++++++++++++2222222")
}

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