public class HelloLua extends Cocos2dxActivity{
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
}
public Cocos2dxGLSurfaceView onCreateGLSurfaceView() {
return new LuaGLSurfaceView(this);
}
static {
System.loadLibrary("hellolua");
}
}
从上面的代码,启动Activity是继承Cocos2dxActivity的,在游戏启动时,Activity首先会执行静态代码块,加载libhellolua.so库,这个动态链接库是在用NDK编译的时候生成的;然后就是执行onCreate方法,这里调用了父类Cocos2dxActivity的onCreate方法。 Cocos2dxActivity在
$(sourcedir)\cocos2dx\platform\android\java\src\org\cocos2dx\lib\Cocos2dxActivity.java
中定义,其OnCreate方法代码如下:
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
sContext = this;
this.mHandler = new Cocos2dxHandler(this);
this.init();
Cocos2dxHelper.init(this, this);
}
这里主要是执行初始化过程,Cocos2dxHandler主要处理显示Dialog的消息,Cocos2dxHelper是个辅助类,我们主要看init()方法,代码如下:
public void init() {
// FrameLayout
ViewGroup.LayoutParams framelayout_params =
new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.FILL_PARENT);
FrameLayout framelayout = new FrameLayout(this);
framelayout.setLayoutParams(framelayout_params);
// Cocos2dxEditText layout
ViewGroup.LayoutParams edittext_layout_params =
new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
Cocos2dxEditText edittext = new Cocos2dxEditText(this);
edittext.setLayoutParams(edittext_layout_params);
// ...add to FrameLayout
framelayout.addView(edittext);
// Cocos2dxGLSurfaceView
this.mGLSurfaceView = this.onCreateView();
// ...add to FrameLayout
framelayout.addView(this.mGLSurfaceView);
// Switch to supported OpenGL (ARGB888) mode on emulator
if (isAndroidEmulator())
this.mGLSurfaceView.setEGLConfigChooser(8 , 8, 8, 8, 16, 0);
this.mGLSurfaceView.setCocos2dxRenderer(new Cocos2dxRenderer());
this.mGLSurfaceView.setCocos2dxEditText(edittext);
// Set framelayout as the content view
setContentView(framelayout);
}
public Cocos2dxGLSurfaceView onCreateView() {
return new Cocos2dxGLSurfaceView(this);
}
$(sourcedir)\cocos2dx\platform\android\java\src\org\cocos2dx\lib\Cocos2dxGLSurfaceView.java
中定义,它继承自opengl中类GLSurfaceView。GLSurfaceView的核心就是Renderer,初始化时会调用Renderer的onSurfaceCreated方法,每一帧的绘制是通过调用Renderer的onDrawFrame方法。Cocos2dxGLSurfaceView的Renderer是一个Cocos2dxRenderer对象,类Cocos2dxRenderer在
$(sourcedir)\cocos2dx\platform\android\java\src\org\cocos2dx\lib\Cocos2dxRenderer.java
中定义,其方法onSurfaceCreated代码如下:
public void onSurfaceCreated(final GL10 pGL10, final EGLConfig pEGLConfig) {
Cocos2dxRenderer.nativeInit(this.mScreenWidth, this.mScreenHeight);
this.mLastTickInNanoSeconds = System.nanoTime();
}
这里主要调用了一个方法nativeInit,nativeInit被声明为:
private static native void nativeInit(final int pWidth, final int pHeight);
即它是一个native的函数,即该函数用C++代码中实现,关于native函数简单说,就是在java在调用C++代码实现的函数,即需要采用JNI技术(可以看成是Java与C++交互的一个协议~)。方法nativeInit对应的C++实现是在(sourcedir)\samples\Lua\HelloLua\proj.android\jni\hellolua\main.cpp中:
void Java_org_cocos2dx_lib_Cocos2dxRenderer_nativeInit(JNIEnv* env, jobject thiz, jint w, jint h)
{
if (!CCDirector::sharedDirector()->getOpenGLView())
{
CCEGLView *view = CCEGLView::sharedOpenGLView();
view->setFrameSize(w, h);
AppDelegate *pAppDelegate = new AppDelegate();
CCApplication::sharedApplication()->run();
}
else
{
.....
}
}
CCDirector* CCDirector::sharedDirector(void)
{
if (!s_SharedDirector)
{
s_SharedDirector = new CCDisplayLinkDirector();
s_SharedDirector->init();
}
return s_SharedDirector;
}
这里的CCCCDisplayLinkDirector是CCDirector的子类,方法init()做一些初始化工作:
bool CCDirector::init(void)
{
setDefaultValues();
//场景相关
...
...
//管理场景的数组栈
m_pobScenesStack = new CCArray();
m_pobScenesStack->init();
// 一些FPS等相关的成员变量初始化
...
...
//初始化调度器对象
m_pScheduler = new CCScheduler();
//动作管理器对象
m_pActionManager = new CCActionManager();
m_pScheduler->scheduleUpdateForTarget(m_pActionManager, kCCPrioritySystem, false);
// touchDispatcher,KeypadDispatcher,Accelerometer等对象初始化
...
...
// CCPoolManager中实现了cocos2d-x CCObject对象的内存管理机制
CCPoolManager::sharedPoolManager()->push();
return true;
}
创建好导演对象后,Java_org_cocos2dx_lib_Cocos2dxRenderer_nativeInit中调用了该对象的getOpenGLView方法:
inline CCEGLView* getOpenGLView(void) { return m_pobOpenGLView; }
该方法返回用于游戏绘制的CCEGLView,在init()中,m_pobOpenGLView复制为NULL。在Android平台下,这个CCEGLView其实没有什么作用,因为游戏都是绘制在Cocos2dxGLSurfaceView上的,因此方法Java_org_cocos2dx_lib_Cocos2dxRenderer_nativeInit接着执行if分支:
CCEGLView *view = CCEGLView::sharedOpenGLView();
view->setFrameSize(w, h);
这里同样创建了游戏中类CCEGLView的唯一实例,类在$(sourcedir)\cocos2dx\platform\android\CCEGLView.cpp中实现。接着执行
AppDelegate *pAppDelegate = new AppDelegate();
CCApplication::sharedApplication()->run();
创建了一个类AppDelegate对象,类AppDelegate在$(sourcedir)\samples\Lua\HelloLua\Classes\AppDelegate.cpp中实现,类AppDelegate在各个平台之间共用的:
class AppDelegate : private cocos2d::CCApplication
{
public:
AppDelegate();
virtual ~AppDelegate();
virtual bool applicationDidFinishLaunching();
virtual void applicationDidEnterBackground();
virtual void applicationWillEnterForeground();
};
该类继承自CCApplication,注意类CCApplication是在$(sourcedir)\cocos2dx\platform\android\CCApplication.cpp中实现的,它的实现是与平台相关的。创建AppDelegate实例的工作实质就是实例化CCApplication,它的构造函数代码如下:
CCApplication::CCApplication()
{
CCAssert(! sm_pSharedApplication, "");
sm_pSharedApplication = this;
}
因此在实例化AppDelegate时,主要工作是用AppDelegate对象初始化全局变量sm_pSharedApplication。接着后面调用CCApplication::sharedApplication()->run(),相关代码如下:
CCApplication* CCApplication::sharedApplication()
{
CCAssert(sm_pSharedApplication, "");
return sm_pSharedApplication;
}
int CCApplication::run()
{
// Initialize instance and cocos2d.
if (! applicationDidFinishLaunching())
{
return 0;
}
return -1;
}
run中调用的虚函数applicationDidFinishLaunching实质上调用的是子类AppDelegate中的applicationDidFinishLaunching,代码如下:
bool AppDelegate::applicationDidFinishLaunching()
{
//初始化director
CCDirector *pDirector = CCDirector::sharedDirector();
pDirector->setOpenGLView(CCEGLView::sharedOpenGLView());
CCEGLView::sharedOpenGLView()->setDesignResolutionSize(480, 320, kResolutionNoBorder);
//显示FPS
pDirector->setDisplayStats(true);
// 设置FPS
pDirector->setAnimationInterval(1.0 / 60);
//创建Lua脚本引擎
CCLuaEngine* pEngine = CCLuaEngine::defaultEngine();
CCScriptEngineManager::sharedManager()->setScriptEngine(pEngine);
//加载执行lua脚本
std::string path = CCFileUtils::sharedFileUtils()->fullPathForFilename("hello.lua");
pEngine->executeScriptFile(path.c_str());
return true;
}
public void onDrawFrame(final GL10 gl) {
Cocos2dxRenderer.nativeRender();
}
其唯一的工作是调用了nativeRender方法,该方法是native的,其对应的实现是:
JNIEXPORT void JNICALL Java_org_cocos2dx_lib_Cocos2dxRenderer_nativeRender(JNIEnv* env) {
cocos2d::CCDirector::sharedDirector()->mainLoop();
}
即执行导演对象中的方法mainLoop:
void CCDisplayLinkDirector::mainLoop(void)
{
// 此变量决定程序是否结束
if (m_bPurgeDirecotorInNextLoop)
{
m_bPurgeDirecotorInNextLoop = false;
purgeDirector();
}
else if (! m_bInvalid)
{
//屏幕绘制,并做一些相应的逻辑处理
drawScene();
// 释放对象管理器中CCObject 对象
CCPoolManager::sharedPoolManager()->pop();
}
}
这个方法就是所有平台最后真正执行的循环体。
参考资料