cocos2d-x_Android应用启动调用过程简析

调用org.cocos2dx.cpp.AppActivity

AppActivity是位于proj.android/src下，是开发者类(即开发者自定义的类)，继承自org.cocos2dx.lib.Cocos2dxActivity，它没有添加任何代码，纯粹是一个Cocos2dxActivity，也是一个Activity。

AppActivity被调用是因为被配置在AndroidManifest.xml

<application android:label="@string/app_name"                 android:icon="@drawable/icon">        <activity android:name="org.cocos2dx.cpp.AppActivity"                  android:label="@string/app_name"                  android:screenOrientation="landscape"                  android:theme="@android:style/Theme.NoTitleBar.Fullscreen"                  android:configChanges="orientation">            <!-- Tell NativeActivity the name of our .so -->            <meta-data android:name="android.app.lib_name"                       android:value="cocos2dcpp" />            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>    </application>

加载libcocos2dcpp.so

libcocos2dcpp.so在编译后生成到proj.android/libs/armeabi下，从上面代码中可以看到android:value=”cocos2dcpp”这行配置内容，它指示了so的名字。

在AppActivity中加载so的代码如下：

@Override    protected void onCreate(final Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        try {            ApplicationInfo ai = getPackageManager().getApplicationInfo(getPackageName(), PackageManager.GET_META_DATA);            Bundle bundle = ai.metaData;            try {                String libName = bundle.getString("android.app.lib_name");                System.loadLibrary(libName);            } catch (Exception e) {                 // ERROR            }        } catch (PackageManager.NameNotFoundException e) {             // ERROR        }        sContext = this;        this.mHandler = new Cocos2dxHandler(this);        this.init();        Cocos2dxHelper.init(this);    }

调用cocos_android_app_init

proj.android/jni/hellocpp/main.cpp中的cocos_android_app_init函数被调用。

我们看看this.init();后续代码片段：

public void init() {        ...        this.mGLSurfaceView.setCocos2dxRenderer(new Cocos2dxRenderer());        ...    }

@Override    public void onSurfaceCreated(final GL10 pGL10, final EGLConfig pEGLConfig) {        Cocos2dxRenderer.nativeInit(this.mScreenWidth, this.mScreenHeight);        this.mLastTickInNanoSeconds = System.nanoTime();    }

到现在前面都是java代码，上段中的Cocos2dxRenderer.nativeInit(this.mScreenWidth, this.mScreenHeight);是一句jni调用，java调用c/c++代码。

其代码在cocos2d/cocos/2d/platform/android/javaactivity.cpp中，如下：

void Java_org_cocos2dx_lib_Cocos2dxRenderer_nativeInit(JNIEnv*  env, jobject thiz, jint w, jint h){    auto director = cocos2d::Director::getInstance();    auto glview = director->getOpenGLView();    if (!glview)    {        glview = cocos2d::GLView::create("Android app");        glview->setFrameSize(w, h);        director->setOpenGLView(glview);        //cocos_android_app_init(env, thiz);        cocos2d::Application::getInstance()->run();    }    else    {        cocos2d::GL::invalidateStateCache();        cocos2d::ShaderCache::getInstance()->reloadDefaultShaders();        cocos2d::DrawPrimitives::init();        cocos2d::VolatileTextureMgr::reloadAllTextures();        cocos2d::EventCustom foregroundEvent(EVENT_COME_TO_FOREGROUND);        director->getEventDispatcher()->dispatchEvent(&foregroundEvent);        director->setGLDefaultValues();    }}

jintArray Java_org_cocos2dx_lib_Cocos2dxActivity_getGLContextAttrs(JNIEnv*  env, jobject thiz)
{
    cocos_android_app_init(env, thiz);
    cocos2d::Application::getInstance()->initGLContextAttrs(); 
    GLContextAttrs _glContextAttrs = GLView::getGLContextAttrs();
    
    int tmp[6] = {_glContextAttrs.redBits, _glContextAttrs.greenBits, _glContextAttrs.blueBits,
                           _glContextAttrs.alphaBits, _glContextAttrs.depthBits, _glContextAttrs.stencilBits};
    jintArray glContextAttrsJava = env->NewIntArray(6);
        env->SetIntArrayRegion(glContextAttrsJava, 0, 6, tmp); 
    
    return glContextAttrsJava;
}

我们看到了cocos_android_app_init(env, thiz);这句，这就和main.cpp中的cocos_android_app_init连接上了。

创建AppDelegate

cocos_android_app_init中创建了AppDelegate，后面的事就交给cocos2d-x引擎吧

void cocos_android_app_init (JNIEnv* env, jobject thiz) {    LOGD("cocos_android_app_init");    AppDelegate *pAppDelegate = new AppDelegate();}