Android 开关机动画显示源码分析

Android系统在启动SystemServer进程时，通过两个阶段来启动系统所有服务，在第一阶段启动本地服务，如SurfaceFlinger，SensorService等，在第二阶段则启动一系列的Java服务。开机动画是在什么时候启动的呢？通过查看源码，Android开机动画是在启动SurfaceFlinger服务时启动的。SystemServer的main函数首先调用init1来启动本地服务，init1函数通过JNI调用C语言中的system_init()函数来实现服务启动。

extern "C" status_t system_init()
{
    sp<ProcessState> proc(ProcessState::self());
    sp<IServiceManager> sm = defaultServiceManager();
    sp<GrimReaper> grim = new GrimReaper();
    sm->asBinder()->linkToDeath(grim, grim.get(), 0);
    char propBuf[PROPERTY_VALUE_MAX];
    property_get("system_init.startsurfaceflinger", propBuf, "1");
    if (strcmp(propBuf, "1") == 0) {
        // Start the SurfaceFlinger
        SurfaceFlinger::instantiate();
    }
	...
    return NO_ERROR;
}

通过调用SurfaceFlinger::instantiate()函数来启动SurfaceFlinger服务，SurfaceFlinger类继承于BinderService模板类，BinderService类的instantiate()函数就是构造对应类型的服务对象，并注册到ServiceManager进程中。

static void instantiate() { publish(); }
static status_t publish(bool allowIsolated = false) {
	sp<IServiceManager> sm(defaultServiceManager());
	return sm->addService(String16(SERVICE::getServiceName()), new SERVICE(), allowIsolated);
}

对于SurfaceFlinger服务来说，就是首先构造SurfaceFlinger对象，然后通过调用ServiceManger的远程Binder代理对象的addService函数来注册SurfaceFlinger服务。这里只介绍SurfaceFlinger的构造过程，对于服务注册过程，在Android服务注册完整过程源码分析中已经介绍的非常详细。

SurfaceFlinger::SurfaceFlinger()
    :   BnSurfaceComposer(), Thread(false),
        mTransactionFlags(0),
        mTransationPending(false),
        mLayersRemoved(false),
        mBootTime(systemTime()),
        mVisibleRegionsDirty(false),
        mHwWorkListDirty(false),
        mElectronBeamAnimationMode(0),
        mDebugRegion(0),
        mDebugDDMS(0),
        mDebugDisableHWC(0),
        mDebugDisableTransformHint(0),
        mDebugInSwapBuffers(0),
        mLastSwapBufferTime(0),
        mDebugInTransaction(0),
        mLastTransactionTime(0),
        mBootFinished(false),
        mSecureFrameBuffer(0)
{
    init();
}

SurfaceFlinger对象实例的构造过程很简单，就是初始化一些成员变量值，然后调用init()函数来完成初始化工作

void SurfaceFlinger::init()
{
    char value[PROPERTY_VALUE_MAX];
    property_get("debug.sf.showupdates", value, "0");
    mDebugRegion = atoi(value);
#ifdef DDMS_DEBUGGING
    property_get("debug.sf.ddms", value, "0");
    mDebugDDMS = atoi(value);
    if (mDebugDDMS) {
        DdmConnection::start(getServiceName());
    }
#endif
    property_get("ro.bootmode", value, "mode");
    if (!(strcmp(value, "engtest")
        && strcmp(value, "special")
        && strcmp(value, "wdgreboot")
        && strcmp(value, "unknowreboot")
        && strcmp(value, "panic"))) {
        SurfaceFlinger::sBootanimEnable = false;
    }
}

在SurfaceFlinger的init函数中，也并没有做任何复杂工作，只是简单读取系统属性得到开机模式，来相应设置一些变量而已，比如是否显示开机动画变量sBootanimEnable。由于SurfaceFlinger继承于RefBase类，并重写了该类的onFirstRef()函数，我们知道，RefBase类的子类对象在第一次创建时，会自动调用onFirstRef()函数，因此在SurfaceFlinger对象构造完成时，将调用onFirstRef()函数。

void SurfaceFlinger::onFirstRef()
{
    mEventQueue.init(this);//事件队列初始化
    run("SurfaceFlinger", PRIORITY_URGENT_DISPLAY);//运行SurfaceFlinger线程
    mReadyToRunBarrier.wait();
}

这里不对SurfaceFlinger的相关内容做详细介绍，本文的主要内容是介绍开机动画显示过程。由于SurfaceFlinger同时继承于线程Thread类，而且SurfaceFlinger并没有重写Thread类的run方法，因此这里调用SurfaceFlinger的run函数，其实调用的就是其父类Thread的run函数。

status_t Thread::run(const char* name, int32_t priority, size_t stack)
{
    Mutex::Autolock _l(mLock);
    if (mRunning) {
        return INVALID_OPERATION;
    }
    mStatus = NO_ERROR;
    mExitPending = false;
    mThread = thread_id_t(-1);
    mHoldSelf = this;
    mRunning = true;
    bool res;
    if (mCanCallJava) {
        res = createThreadEtc(_threadLoop,this, name, priority, stack, &mThread);
    } else {
        res = androidCreateRawThreadEtc(_threadLoop,this, name, priority, stack, &mThread);
    }
    if (res == false) {
        mStatus = UNKNOWN_ERROR;   // something happened!
        mRunning = false;
        mThread = thread_id_t(-1);
        mHoldSelf.clear();  // "this" may have gone away after this.
        return UNKNOWN_ERROR;
    }
    return NO_ERROR;
}

该函数就是创建一个线程，并运行现在执行函数_threadLoop

int Thread::_threadLoop(void* user)
{
    Thread* const self = static_cast<Thread*>(user);
    sp<Thread> strong(self->mHoldSelf);
    wp<Thread> weak(strong);
    self->mHoldSelf.clear();
#ifdef HAVE_ANDROID_OS
    self->mTid = gettid();
#endif
    bool first = true;
    do {
        bool result;
        if (first) {
            first = false;
            self->mStatus = self->readyToRun();
            result = (self->mStatus == NO_ERROR);
            if (result && !self->exitPending()) {
                result = self->threadLoop();
            }
        } else {
            result = self->threadLoop();
        }
        {
        Mutex::Autolock _l(self->mLock);
        if (result == false || self->mExitPending) {
            self->mExitPending = true;
            self->mRunning = false;
            self->mThread = thread_id_t(-1);
            self->mThreadExitedCondition.broadcast();
            break;
        }
        }
        strong.clear();
        strong = weak.promote();
    } while(strong != 0);
    return 0;
}

在线程开始运行时，变量first为true，因此会调用self->readyToRun()来做一些初始化工作，同时将变量first设置为false，在以后线程执行过程中，就反复执行self->threadLoop()了。作为Thread类的子类SurfaceFlinger重写了这两个方法，因此创建的SurfaceFlinger线程在执行前会调用SurfaceFlinger的readyToRun()函数完成初始化任务，然后反复执行SurfaceFlinger的threadLoop()函数。

status_t SurfaceFlinger::readyToRun()
{
    ALOGI(   "SurfaceFlinger's main thread ready to run. "
            "Initializing graphics H/W...");
    int dpy = 0;
    {
        // initialize the main display
        GraphicPlane& plane(graphicPlane(dpy));
        DisplayHardware* const hw = new DisplayHardware(this, dpy);
        plane.setDisplayHardware(hw);
    }
    // create the shared control-block
    mServerHeap = new MemoryHeapBase(4096,MemoryHeapBase::READ_ONLY, "SurfaceFlinger read-only heap");
    ALOGE_IF(mServerHeap==0, "can't create shared memory dealer");
    mServerCblk = static_cast<surface_flinger_cblk_t*>(mServerHeap->getBase());
    ALOGE_IF(mServerCblk==0, "can't get to shared control block's address");
    new(mServerCblk) surface_flinger_cblk_t;
    // initialize primary screen
    const GraphicPlane& plane(graphicPlane(dpy));
    const DisplayHardware& hw = plane.displayHardware();
    const uint32_t w = hw.getWidth();
    const uint32_t h = hw.getHeight();
    const uint32_t f = hw.getFormat();
    hw.makeCurrent();
    // initialize the shared control block
    mServerCblk->connected |= 1<<dpy;
    display_cblk_t* dcblk = mServerCblk->displays + dpy;
    memset(dcblk, 0, sizeof(display_cblk_t));
    dcblk->w            = plane.getWidth();
    dcblk->h            = plane.getHeight();
    dcblk->format       = f;
    dcblk->orientation  = ISurfaceComposer::eOrientationDefault;
    dcblk->xdpi         = hw.getDpiX();
    dcblk->ydpi         = hw.getDpiY();
    dcblk->fps          = hw.getRefreshRate();
    dcblk->density      = hw.getDensity();
    // Initialize OpenGL|ES
    glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
    glPixelStorei(GL_PACK_ALIGNMENT, 4);
    glEnableClientState(GL_VERTEX_ARRAY);
    glShadeModel(GL_FLAT);
    glDisable(GL_DITHER);
    glDisable(GL_CULL_FACE);
    const uint16_t g0 = pack565(0x0F,0x1F,0x0F);
    const uint16_t g1 = pack565(0x17,0x2f,0x17);
    const uint16_t wormholeTexData[4] = { g0, g1, g1, g0 };
    glGenTextures(1, &mWormholeTexName);
    glBindTexture(GL_TEXTURE_2D, mWormholeTexName);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 2, 2, 0,GL_RGB, GL_UNSIGNED_SHORT_5_6_5, wormholeTexData);
    const uint16_t protTexData[] = { pack565(0x03, 0x03, 0x03) };
    glGenTextures(1, &mProtectedTexName);
    glBindTexture(GL_TEXTURE_2D, mProtectedTexName);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 1, 1, 0,GL_RGB, GL_UNSIGNED_SHORT_5_6_5, protTexData);
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    // put the origin in the left-bottom corner
    glOrthof(0, w, 0, h, 0, 1); // l=0, r=w ; b=0, t=h
    // start the EventThread
    mEventThread = new EventThread(this);
    mEventQueue.setEventThread(mEventThread);
    hw.startSleepManagement();
    /*
     *  We're now ready to accept clients...
     */
    mReadyToRunBarrier.open();
    // start boot animation
    startBootAnim();
    return NO_ERROR;
}

该函数首先是初始化Android的图形显示系统，启动SurfaceFlinger事件线程，这些内容只有了解了Android的显示原理及SurfaceFlinger服务之后才能理解，这里不做介绍。当显示系统初始化完毕后，调用startBootAnim()函数来显示开机动画。

void SurfaceFlinger::startBootAnim() {
    // start boot animation
    if(SurfaceFlinger::sBootanimEnable){
        property_set("service.bootanim.exit", "0");
        property_set("ctl.start", "bootanim");
    }
}

startBootAnim()函数比较简单，就是通过判断开机动画的变量值了决定是否显示开机动画。启动开机动画进程也是通过Android属性系统来实现的，具体启动过程可以查看 Android 系统属性SystemProperty分析。在Android系统启动脚本init.rc中配置了开机动画服务进程。

property_set("ctl.start", "bootanim")就是启动bootanim进程来显示开机动画，该进程对应的源码位于frameworks\base\cmds\bootanimation\bootanimation_main.cpp

int main(int argc, char** argv)
{
#if defined(HAVE_PTHREADS)
    setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_DISPLAY);
#endif
    char value[PROPERTY_VALUE_MAX];
    property_get("debug.sf.nobootanimation", value, "0");
    int noBootAnimation = atoi(value);
    ALOGI_IF(noBootAnimation,  "boot animation disabled");
    if (!noBootAnimation) {
		/*modify  boot animation and added shutdown animation*/
		char argvtmp[2][BOOTANIMATION_PATHSET_MAX];
		memset(argvtmp[0],0,BOOTANIMATION_PATHSET_MAX);
		memset(argvtmp[1],0,BOOTANIMATION_PATHSET_MAX);
		//没有参数时，执行开机动画，
		if(argc<2){
			//开机动画文件BOOTANIMATION_BOOT_FILM_PATH_DEFAULT="/system/media/bootanimation.zip"
			strncpy(argvtmp[0],BOOTANIMATION_BOOT_FILM_PATH_DEFAULT,BOOTANIMATION_PATHSET_MAX);
			//开机声音文件BOOTANIMATION_BOOT_SOUND_PATH_DEFAULT="/system/media/bootsound.mp3"
			strncpy(argvtmp[1],BOOTANIMATION_BOOT_SOUND_PATH_DEFAULT,BOOTANIMATION_PATHSET_MAX);
		}else{//否则执行关机动画
			//关机动画文件BOOTANIMATION_SHUTDOWN_FILM_PATH_DEFAULT="/system/media/shutdownanimation.zip"
			strncpy(argvtmp[0],BOOTANIMATION_SHUTDOWN_FILM_PATH_DEFAULT,BOOTANIMATION_PATHSET_MAX);
			//关机声音文件BOOTANIMATION_SHUTDOWN_SOUND_PATH_DEFAULT="/system/media/shutdownsound.mp3"
			strncpy(argvtmp[1],BOOTANIMATION_SHUTDOWN_SOUND_PATH_DEFAULT,BOOTANIMATION_PATHSET_MAX);
		}
		__android_log_print(ANDROID_LOG_INFO,"BootAnimation", "begine bootanimation!");
		//启动Binder线程池，用于接收其他进程的请求
		sp<ProcessState> proc(ProcessState::self());
		ProcessState::self()->startThreadPool();
		//创建BootAnimation对象
		BootAnimation *boota = new BootAnimation();
		String8 descname("desc.txt");
		if(argc<2){//设置开机动画文件的默认路径
			String8 mpath_default(BOOTANIMATION_BOOT_FILM_PATH_DEFAULT);
			String8 spath_default(BOOTANIMATION_BOOT_SOUND_PATH_DEFAULT);
			boota->setmoviepath_default(mpath_default);
			boota->setsoundpath_default(spath_default);
			//boota->setdescname_default(descname_default);
		}else {//设置关机动画文件的默认路径
			String8 mpath_default(BOOTANIMATION_SHUTDOWN_FILM_PATH_DEFAULT);
			String8 spath_default(BOOTANIMATION_SHUTDOWN_SOUND_PATH_DEFAULT);
			boota->setmoviepath_default(mpath_default);
			boota->setsoundpath_default(spath_default);
			//boota->setdescname_default(descname_default);
			__android_log_print(ANDROID_LOG_INFO,"BootAnimation","shutdown exe bootanimation!");
		}
		String8 mpath(argvtmp[0]);
		String8 spath(argvtmp[1]);
		//设置动画的文件路径
		boota->setmoviepath(mpath);
		boota->setsoundpath(spath);
		boota->setdescname(descname);
		__android_log_print(ANDROID_LOG_INFO,"BootAnimation","%s", mpath.string());
		__android_log_print(ANDROID_LOG_INFO,"BootAnimation","%s", spath.string());
		sp<BootAnimation> bootsp = boota;
		//将当前线程注册到Binder线程池中
		IPCThreadState::self()->joinThreadPool();
	}
	return 0;
}

该函数构造了一个BootAnimation对象，并且为该对象设置了开关机动画及声音文件路径，同时创建了Binder线程池，并将bootanim进程的主线程注册到Binder线程池中，用于接收客户进程的Binder通信请求。

BootAnimation::BootAnimation() : Thread(false)
{
    mSession = new SurfaceComposerClient();
}

在构造BootAnimation对象时，实例化SurfaceComposerClient对象，用于请求SurfaceFlinger显示开关机动画。由于BootAnimation类继承于RefBase，同时重写了onFirstRef()函数，因此在构造BootAnimation对象时，会调用该函数。

void BootAnimation::onFirstRef() {
    status_t err = mSession->linkToComposerDeath(this);
    ALOGE_IF(err, "linkToComposerDeath failed (%s) ", strerror(-err));
    if (err == NO_ERROR) {
        run("BootAnimation", PRIORITY_DISPLAY);
    }
}

该函数首先为SurfaceComposerClient对象注册Binder死亡通知,然后调用BootAnimation的run方法,由于BootAnimation同时继承于Thread类,前面介绍SurfaceFlinger时已经介绍到,当某个类继承于Thread类时,当调用该类的run函数时,函数首先会执行readyToRun()函数来完成线程执行前的一些工作,然后线程反复执行threadLoop()函数,在BootAnimation类中,同样重新了这两个方法

status_t BootAnimation::readyToRun() {
    //force screen display in vertical layout
    mSession->setOrientation(0, 0, 0);
    mAssets.addDefaultAssets();
    DisplayInfo dinfo;
    status_t status = session()->getDisplayInfo(0, &dinfo);
    if (status)
        return -1;
    // create the native surface
    sp<SurfaceControl> control;
    if (dinfo.w > dinfo.h) {
        control = session()->createSurface(0, dinfo.h, dinfo.w, PIXEL_FORMAT_RGB_565);
    } else {
        control = session()->createSurface(0, dinfo.w, dinfo.h, PIXEL_FORMAT_RGB_565);
    }
    SurfaceComposerClient::openGlobalTransaction();
    control->setLayer(0x40000000);
    SurfaceComposerClient::closeGlobalTransaction();
    sp<Surface> s = control->getSurface();
    // initialize opengl and egl
    const EGLint attribs[] = {
            EGL_RED_SIZE,   8,
            EGL_GREEN_SIZE, 8,
            EGL_BLUE_SIZE,  8,
            EGL_DEPTH_SIZE, 0,
            EGL_NONE
    };
    EGLint w, h, dummy;
    EGLint numConfigs;
    EGLConfig config;
    EGLSurface surface;
    EGLContext context;
    EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
    eglInitialize(display, 0, 0);
    eglChooseConfig(display, attribs, &config, 1, &numConfigs);
    surface = eglCreateWindowSurface(display, config, s.get(), NULL);
    context = eglCreateContext(display, config, NULL, NULL);
    eglQuerySurface(display, surface, EGL_WIDTH, &w);
    eglQuerySurface(display, surface, EGL_HEIGHT, &h);
    if (eglMakeCurrent(display, surface, surface, context) == EGL_FALSE)
        return NO_INIT;
    mDisplay = display;
    mContext = context;
    mSurface = surface;
    mWidth = w;
    mHeight = h;
    mFlingerSurfaceControl = control;
    mFlingerSurface = s;
    mAndroidAnimation = true;
    // If the device has encryption turned on or is in process 
    // of being encrypted we show the encrypted boot animation.
    char decrypt[PROPERTY_VALUE_MAX];
    property_get("vold.decrypt", decrypt, "");
    bool encryptedAnimation = atoi(decrypt) != 0 || !strcmp("trigger_restart_min_framework", decrypt);
	//如果"/system/media/bootanimation-encrypted.zip"文件存在或者设置的动画文件存在，或者默认动画文件存在，或者"/data/local/bootanimation.zip"文件存在，都显示开机动画文件，否则显示Android滚动字样
	if ((encryptedAnimation &&
            (access(SYSTEM_ENCRYPTED_BOOTANIMATION_FILE, R_OK) == 0) &&
            (mZip.open(SYSTEM_ENCRYPTED_BOOTANIMATION_FILE) == NO_ERROR)) ||
            ((access(moviepath, R_OK) == 0) &&
            (mZip.open(moviepath) == NO_ERROR)) ||
            ((access(movie_default_path, R_OK) == 0) &&
            (mZip.open(movie_default_path) == NO_ERROR)) ||
            ((access(USER_BOOTANIMATION_FILE, R_OK) == 0) &&
            (mZip.open(USER_BOOTANIMATION_FILE) == NO_ERROR))) {
        mAndroidAnimation = false;
    }
    return NO_ERROR;
}

在该函数里创建SurfaceControl对象,通过SurfaceControl对象得到Surface对象,并初始化好OpenGL，同时判断动画文件是否存在，如果不存在，则设置标志位mAndroidAnimation为true，表示显示Android滚动字样。当初始化完这些必需资源后，线程进入循环执行体threadLoop()

bool BootAnimation::threadLoop()
{
    bool r;
	//如果mAndroidAnimation为true，表示动画文件不存在，则显示Android滚动字样
    if (mAndroidAnimation) {
        r = android();
    } else {//显示动画
        r = movie();
    }
	//资源回收
    eglMakeCurrent(mDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
    eglDestroyContext(mDisplay, mContext);
    eglDestroySurface(mDisplay, mSurface);
    mFlingerSurface.clear();
    mFlingerSurfaceControl.clear();
    eglTerminate(mDisplay);
    IPCThreadState::self()->stopProcess();
    return r;
}

开机画面主要是由一个zip格式的压缩包bootanimation.zip组成，压缩包里面包含数张png格式的图片，还有一个desc.txt的文本文档，开机时按desc.txt里面的指令，屏幕上会按文件名称顺序连续的播放一张张的图片，就像播放原始的胶带影片一样，形成动画。desc.txt是一个保存形式为ANSI格式的文件，用于设置这个动画像素（大小），帧数，闪烁次数，文件夹名称等。内容如下：
480 854 10
p 1 2 folder1
p 0 2 folder2

480 427 30  ---这里的480代表图片的像素（大小）宽度，427代表图片的像素（大小）高度，30代表帧数；

p 1 0 part0 ---这里的p代表标志符，1代表循环次数为1次，0代表阶段间隔时间为0，part0代表对应的文件夹名，为第一阶段动画图片目录；

p 0 0 part1---这里的p代表标志符，0代表本阶段无限循环，0代表阶段间隔时间为0，part1代表对应的文件夹名，为第二阶段动画图片目录；

阶段切换间隔时间：单位是一个帧的持续时间，比如帧数是30，那么帧的持续时间就是1秒/30 = 33.3毫秒。阶段切换间隔时间期间开机动画进程进入休眠，把CPU时间让给初始化系统使用。也就是间隔长启动会快，但会影响动画效果。
folder1和folder2文件夹内包含的是两个动画的系列图片，图片为PNG格式。

bool BootAnimation::movie()
{
    ZipFileRO& zip(mZip);
	//获取zip压缩文件中的文件数目
    size_t numEntries = zip.getNumEntries();
	//打开zip压缩文件中的desc.txt文件
    ZipEntryRO desc = zip.findEntryByName("desc.txt");
    FileMap* descMap = zip.createEntryFileMap(desc);
    ALOGE_IF(!descMap, "descMap is null");
    if (!descMap) {
        return false;
    }
	//读取desc.txt文件内容
    String8 desString((char const*)descMap->getDataPtr(),descMap->getDataLength());
    char const* s = desString.string();
    Animation animation;
	//读取persist.sys.silence属性来决定是否播放开机音乐
    char silence[PROPERTY_VALUE_MAX];
    property_get("persist.sys.silence", silence, "0");
    if(strcmp("1", silence)==0){
        // do something.
    }else{
        soundplay();
    }
	//解析desc.txt文件内容
    for (;;) {	   //从字符串s中查找是否有字符串"\n"，如果有，返回s中"\n"起始位置的指针，如果没有，返回null。
        const char* endl = strstr(s, "\n");
        if (!endl) break;
		//取得文件一行内容
        String8 line(s, endl - s);
        const char* l = line.string();
        int fps, width, height, count, pause;
        char path[256];
        char pathType;
		//从文件第一行中读取宽度，高度，帧数
		//480 854 10 <---> width height fps
        if (sscanf(l, "%d %d %d", &width, &height, &fps) == 3) {
            //LOGD("> w=%d, h=%d, fps=%d", fps, width, height);
            animation.width = (width > 0 ? width : mWidth);
            animation.height = (height > 0 ? height : mHeight);
            animation.fps = fps;
		//p 1 2 folder1 <---> pathType count pause path
        }else if (sscanf(l, " %c %d %d %s", &pathType, &count, &pause, path) == 4) {
            //LOGD("> type=%c, count=%d, pause=%d, path=%s", pathType, count, pause, path);
            Animation::Part part;//一个part描述一个动画文件夹内容
            part.playUntilComplete = pathType == 'c';
            part.count = count;
            part.pause = pause;
            part.path = path;
            animation.parts.add(part);
        }
        s = ++endl;
    }
    //读取动画个数
    const size_t pcount = animation.parts.size();
	//遍历zip压缩包中的所有文件
    for (size_t i=0 ; i<numEntries ; i++) {
        char name[256];
        ZipEntryRO entry = zip.findEntryByIndex(i);
		//读取压缩包中的文件名称，所在目录的路径
        if (zip.getEntryFileName(entry, name, 256) == 0) {
            const String8 entryName(name);
            const String8 path(entryName.getPathDir());
            const String8 leaf(entryName.getPathLeaf());
            if (leaf.size() > 0) {
                for (int j=0 ; j<pcount ; j++) {
                    if (path == animation.parts[j].path) {
                        int method;
                        //获取文件信息
                        if (zip.getEntryInfo(entry, &method, 0, 0, 0, 0, 0)) {
                            if (method == ZipFileRO::kCompressStored) {
                                FileMap* map = zip.createEntryFileMap(entry);
                                if (map) {
                                    Animation::Frame frame;
                                    frame.name = leaf;
                                    frame.map = map;
                                    Animation::Part& part(animation.parts.editItemAt(j));
                                    part.frames.add(frame);
                                }
                            }
                        }
                    }
                }
            }
        }
    }
    // clear screen
    glShadeModel(GL_FLAT);
    glDisable(GL_DITHER);
    glDisable(GL_SCISSOR_TEST);
    glDisable(GL_BLEND);
    glClearColor(0,0,0,1);
    glClear(GL_COLOR_BUFFER_BIT);
    eglSwapBuffers(mDisplay, mSurface);
    glBindTexture(GL_TEXTURE_2D, 0);
    glEnable(GL_TEXTURE_2D);
    glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    const int xc = (mWidth - animation.width) / 2;
    const int yc = ((mHeight - animation.height) / 2);
    nsecs_t lastFrame = systemTime();
    nsecs_t frameDuration = s2ns(1) / animation.fps;
    Region clearReg(Rect(mWidth, mHeight));
    clearReg.subtractSelf(Rect(xc, yc, xc+animation.width, yc+animation.height));
    for (int i=0 ; i<pcount ; i++) {
        const Animation::Part& part(animation.parts[i]);
        const size_t fcount = part.frames.size();
        glBindTexture(GL_TEXTURE_2D, 0);
		//循环显示文件夹下的图片
        for (int r=0 ; !part.count || r<part.count ; r++) {
            // Exit any non playuntil complete parts immediately
            if(exitPending() && !part.playUntilComplete)
                break;
            for (int j=0 ; j<fcount && (!exitPending() || part.playUntilComplete) ; j++) {
                const Animation::Frame& frame(part.frames[j]);
                nsecs_t lastFrame = systemTime();
                if (r > 0) {
                    glBindTexture(GL_TEXTURE_2D, frame.tid);
                } else {
                    if (part.count != 1) {
                        glGenTextures(1, &frame.tid);
                        glBindTexture(GL_TEXTURE_2D, frame.tid);
                        glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                        glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
                    }
                    initTexture(frame.map->getDataPtr(),frame.map->getDataLength());
                }
                if (!clearReg.isEmpty()) {
                    Region::const_iterator head(clearReg.begin());
                    Region::const_iterator tail(clearReg.end());
                    glEnable(GL_SCISSOR_TEST);
                    while (head != tail) {
                        const Rect& r(*head++);
                        glScissor(r.left, mHeight - r.bottom,
                                r.width(), r.height());
                        glClear(GL_COLOR_BUFFER_BIT);
                    }
                    glDisable(GL_SCISSOR_TEST);
                }
                glDrawTexiOES(xc, yc, 0, animation.width, animation.height);
                eglSwapBuffers(mDisplay, mSurface);
                nsecs_t now = systemTime();
                nsecs_t delay = frameDuration - (now - lastFrame);
                //ALOGD("%lld, %lld", ns2ms(now - lastFrame), ns2ms(delay));
                lastFrame = now;
                if (delay > 0) {
                    struct timespec spec;
                    spec.tv_sec  = (now + delay) / 1000000000;
                    spec.tv_nsec = (now + delay) % 1000000000;
                    int err;
                    do {
                        err = clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &spec, NULL);
                    } while (err<0 && errno == EINTR);
                }
                checkExit();
            }
            usleep(part.pause * ns2us(frameDuration));
            // For infinite parts, we've now played them at least once, so perhaps exit
            if(exitPending() && !part.count)
                break;
        }
        // free the textures for this part
        if (part.count != 1) {
            for (int j=0 ; j<fcount ; j++) {
                const Animation::Frame& frame(part.frames[j]);
                glDeleteTextures(1, &frame.tid);
            }
        }
    }
	//停止播放开机音乐
    soundstop();
    return false;
}

开机音乐播放过程

bool BootAnimation::soundplay()
{
	mp = NULL;
	if(soundpath.length() == 0){
		__android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "sound resource is not right.");
		return false;
	}
	//打开设置的开机音乐文件
	int fd = open(soundpath.string(), O_RDONLY);
	if(fd == -1){
		__android_log_print(ANDROID_LOG_WARN, LOG_TAG, "boot animation play default source.");
		close(fd);
		//如果没有设置开机音乐文件路径，则打开默认的开机音乐文件
		fd = open(sound_default_path.string(),O_RDONLY);
		if(fd == -1){
			close(fd);
			__android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "can not find bootanimation resource....");
			return false;
		}
	}
	mp = new MediaPlayer();
	mp->setDataSource(fd, 0, 0x7ffffffffffffffLL);
	mp->setAudioStreamType(/*AUDIO_STREAM_MUSIC*/AUDIO_STREAM_SYSTEM);
	mp->prepare();
	mp->start();
	return false;
}

整个开关机动画就完成了，那关机动画是如何启动的呢？下一篇继续介绍Android系统的关机流程！