【2014-01-27】cocos2dx学习笔记：CCNode回调流程

[历史归档]本文原发布于 cstriker1407.info 个人博客内容为历史存档仅供参考。发布时间2014-01-27 标题cocos2dx学习笔记CCNode回调流程分类编程 / C C / cocos2dx 标签cocos2dxcocos2dx学习笔记CCNode回调流程CCNode的回调流程CCNode的几个回调函数cocos2dx程序框架流程首先进入main.cpp函数可以发现程序调用了Appliaction的run方法然后查看run方法是一个while1循环调用了Director的mainloop方法查看mainLoop方法发现其调用了drawScene方法查看drawScene方法没有场景切换动画时的回调流程void CCDirector::setNextScene(void)有场景切换动画时的回调流程从场景A切换到场景XCCTransitionScene和CCTransitionShrinkGrow片段由场景X切换场景B:最近项目中用到了cocos2dx来开发一个基于陀螺仪的demo忙了半个星期一边学习一边开发总算搞了出来。这里备份下开发中学习到的一些cocos2dx知识。CCNode的回调流程在使用CCLayerCCScene的时候往往想在layer或者场景切换的时候处理一些资源类的东西于是就在CCNode里发现了一些回调函数但是这些回调函数如何调用作者在网上也没有搜索自己翻了下源码发现比较简单。在这里备份下。CCNode的几个回调函数classCC_DLLCCNode:publicCCObject{public:。。。。。 。。。。。virtualboolinit();staticCCNode*create(void);/** * Event callback that is invoked every time when CCNode enters the stage. * If the CCNode enters the stage with a transition, this event is called when the transition starts. * During onEnter you cant access a sister/brother node. * If you override onEnter, you shall call its parents one, e.g., CCNode::onEnter(). * js NA * lua NA */virtualvoidonEnter();/** Event callback that is invoked when the CCNode enters in the stage. * If the CCNode enters the stage with a transition, this event is called when the transition finishes. * If you override onEnterTransitionDidFinish, you shall call its parents one, e.g. CCNode::onEnterTransitionDidFinish() * js NA * lua NA */virtualvoidonEnterTransitionDidFinish();/** * Event callback that is invoked every time the CCNode leaves the stage. * If the CCNode leaves the stage with a transition, this event is called when the transition finishes. * During onExit you cant access a sibling node. * If you override onExit, you shall call its parents one, e.g., CCNode::onExit(). * js NA * lua NA */virtualvoidonExit();/** * Event callback that is called every time the CCNode leaves the stage. * If the CCNode leaves the stage with a transition, this callback is called when the transition starts. * js NA * lua NA */virtualvoidonExitTransitionDidStart();/// } end of event callbacks./** * Stops all running actions and schedulers */virtualvoidcleanup(void);。。。。。 。。。。。};cocos2dx程序框架流程首先进入main.cpp函数可以发现程序调用了Appliaction的run方法intAPIENTRY_tWinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPTSTR lpCmdLine,intnCmdShow){。。。。。 。。。。。returnCCApplication::sharedApplication()-run();}然后查看run方法是一个while1循环调用了Director的mainloop方法intCCApplication::run(){。。。。。 。。。。。while(1){。。。。。CCDirector::sharedDirector()-mainLoop();。。。。。}。。。。。}查看mainLoop方法发现其调用了drawScene方法voidCCDisplayLinkDirector::mainLoop(void){。。。。。 。。。。。drawScene();。。。。。}查看drawScene方法voidCCDirector::drawScene(void){。。。。。 。。。。。if(m_pNextScene){setNextScene();}。。。。。if(m_pRunningScene){m_pRunningScene-visit();}。。。。。}查看代码到这里就可以大致的知道cocos2dx程序的运行流程通过不停的循环来执行当前scene的visit方法绘制界面如果有场景切换就切换场景后继续visiit。这里作者不关心visit和draw方法只关注于CCNode的回调流程。没有场景切换动画时的回调流程void CCDirector::setNextScene(void)voidCCDirector::setNextScene(void){boolrunningIsTransitiondynamic_castCCTransitionScene*(m_pRunningScene)!NULL;boolnewIsTransitiondynamic_castCCTransitionScene*(m_pNextScene)!NULL;// If it is not a transition, call onExit/cleanupif(!newIsTransition){if(m_pRunningScene){m_pRunningScene-onExitTransitionDidStart();m_pRunningScene-onExit();}// issue #709. the root node (scene) should receive the cleanup message too// otherwise it might be leaked.if(m_bSendCleanupToScenem_pRunningScene){m_pRunningScene-cleanup();}}if(m_pRunningScene){m_pRunningScene-release();}m_pRunningScenem_pNextScene;m_pNextScene-retain();m_pNextSceneNULL;if((!runningIsTransition)m_pRunningScene){m_pRunningScene-onEnter();m_pRunningScene-onEnterTransitionDidFinish();}}通过查看setNextScene的方法就可以发现在没有场景切换动画时各个回调函数的调用流程很清楚了。首先调用要退出场景的 onExitTransitionDidStart 方法和 onExit 方法如果当前是切换场景不是push场景就继续调用cleanup方法最后在执行新场景的 onEnter 和 onEnterTransitionDidFinish 方法。我们查看下这4个onXXXX方法CCScene和CCLayer均继承自CCNode这4个方法也是CCNode的方法。我们以onEnter为例voidCCNode::onEnter(){arrayMakeObjectsPerformSelector(m_pChildren,onEnter,CCNode*);。。。。。}可以发现里面有个宏这个就是关键所在~~宏的定义如下#definearrayMakeObjectsPerformSelector(pArray,func,elementType)\do{\if(pArraypArray-count()0)\{\CCObject*child;\CCARRAY_FOREACH(pArray,child)\{\elementType pNode(elementType)child;\if(pNode)\{\pNode-func();\}\}\}\}\while(false)由此就很清晰了当场景切换时新老场景的各个回调方法会被回调这些回调方法又会递归调用其children的相同的回调方法由于CCSceneCCLayerCCSprite等在cocos2dx的场景构建时为父子关系那么场景中的各种元素都会回调一次。有场景切换动画时的回调流程有场景动画时回调比较复杂一点首先需要明确的是场景切换动画也是场景。这样当场景A通过动画X切换到场景B时实际上是有3个场景AXB。为了便于分析我们假设场景切换动画X为 CCTransitionShrinkGrow 类的动画。从场景A切换到场景X回到函数 void CCDirector::setNextScene(void) 中当从A切到X时m_pRunningScene 是场景Am_pNextScene 是场景XA不是场景切换动画类CCTransitionShrinkGrowCCTransitionSceneX是场景切换动画类。那么根据函数逻辑函数流程会直接走向场景X的onEnter和onEnterXXX函数但不会走向场景A的onExitXXX和onExit函数。CCTransitionScene和CCTransitionShrinkGrow片段代码较多但是根据代码的走向就很清晰了。classCC_DLLCCTransitionScene:publicCCScene{protected:CCScene*m_pInScene;CCScene*m_pOutScene;。。。。。 。。。。。}classCC_DLLCCTransitionShrinkGrow:publicCCTransitionScene,publicCCTransitionEaseScene{。。。。。 。。。。。}CCTransitionScene*CCTransitionScene::create(floatt,CCScene*scene){CCTransitionScene*pScenenewCCTransitionScene();if(pScenepScene-initWithDuration(t,scene)){pScene-autorelease();returnpScene;}CC_SAFE_DELETE(pScene);returnNULL;}boolCCTransitionScene::initWithDuration(floatt,CCScene*scene){CCAssert(scene!NULL,Argument scene must be non-nil);if(CCScene::init()){m_fDurationt;// retainm_pInScenescene;m_pInScene-retain();m_pOutSceneCCDirector::sharedDirector()-getRunningScene();if(m_pOutSceneNULL){m_pOutSceneCCScene::create();m_pOutScene-init();}m_pOutScene-retain();CCAssert(m_pInScene!m_pOutScene,Incoming scene must be different from the outgoing scene);sceneOrder();returntrue;}else{returnfalse;}}voidCCTransitionScene::finish(){。。。。。 。。。。。this-schedule(schedule_selector(CCTransitionScene::setNewScene),0);}voidCCTransitionScene::setNewScene(floatdt){。。。。。 CCDirector*directorCCDirector::sharedDirector();。。。。。 director-replaceScene(m_pInScene);。。。。。}// custom onEntervoidCCTransitionScene::onEnter(){CCScene::onEnter();// disable events while transitionsCCDirector::sharedDirector()-getTouchDispatcher()-setDispatchEvents(false);// outScene should not receive the onEnter callback// only the onExitTransitionDidStartm_pOutScene-onExitTransitionDidStart();m_pInScene-onEnter();}// custom onExitvoidCCTransitionScene::onExit(){CCScene::onExit();// enable events while transitionsCCDirector::sharedDirector()-getTouchDispatcher()-setDispatchEvents(true);m_pOutScene-onExit();// m_pInScene should not receive the onEnter callback// only the onEnterTransitionDidFinishm_pInScene-onEnterTransitionDidFinish();}voidCCTransitionShrinkGrow::onEnter(){CCTransitionScene::onEnter();。。。。。 。。。。。 m_pInScene-runAction(this-easeActionWithAction(scaleIn));m_pOutScene-runAction(CCSequence::create(this-easeActionWithAction(scaleOut),CCCallFunc::create(this,callfunc_selector(CCTransitionScene::finish)),NULL));}首先当走向场景X的onEnter时CCTransitionShrinkGrow类的onEnter函数首先调用了父类CCTransitionScene的onEnter函数然后调用了CCTransitionScene的finish函数。根据CCTransitionScene的initXX函数可以知道在CCTransitionScene中m_pInScene是场景Bm_pOutScene是场景A那么根据CCTransitionScene的onEnter函数的逻辑知道此时场景A的onExitXXX被调用场景B的onEnter被调用。再来分析CCTransitionScene的finish函数该函数又调用了CCTransitionScene的setNewScene函数在该函数中我们发现程序调用了我们熟悉的ReplaceScene函数前面已经知道了m_pInScene是场景B即程序现在开始执行由场景X切换场景B。由场景X切换场景B:和上面一样我们分析void CCDirector::setNextScene(void) 中当从X切到B时m_pRunningScene 是场景Xm_pNextScene 是场景BB不是场景切换动画类CCTransitionShrinkGrowCCTransitionSceneX是场景切换动画类。那么根据函数逻辑函数流程会走向场景X的onExitXXX和onExit函数但是不会执行场景B的onEnter和onEnterXXX函数。场景X类是CCTransitionShrinkGrow类执行场景X的onExitXXX函数和onExit函数时会进入CCTransitionScene函数的onExit函数由于cocos2dx是类实例指针传递因此这里的实例和上面由A切到X的类实例是一个那么m_pInScene依然是场景Bm_pOutScene依然是场景A在CCTransitionScene函数的onExit函数里场景A的onExit被调用场景B的onEnterXXX被调用。此时整个场景切换过程已经完成。综上可得没有切换动画时调用流程A: onExitTransitionDidStartA: onExitB: onEnterB: onEnterTransitionDidFinish有切换动画时调用流程A: onExitTransitionDidStartB: onEnterA: onExitB: onEnterTransitionDidFinish