android系统知识（8.0）---Android O 开关机动画流程

Android O 开关机动画流程

开机动画 bootanim的启动

开机动画是在进程bootanim ,先看一下bootanim.rc中文件：

android_o/frameworks/base/cmds/bootanimation/bootanim.rc

service bootanim /system/bin/bootanimation
     class core animation
     user graphics
     group graphics audio
     disabled  //服务不会自动运行,必须显式地通过服务器来启动
     oneshot  //当此服务退出时不会自动重启
     writepid /dev/stune/top-app/tasks

• 说明： 

1. 应用程序bootanimation的用户user 和用户组名group 称分别被设置为graphics 
2. 用来启动应用程序bootanimation的服务bootanim 是disabled 的,因此init进程在启动的时候，不会主动将应用程序bootanimation启动起来

SurfaceFlinger服务启动时，它会通过修改系统属性ctl.start的值来通知init进程启动应用程序bootanimation，而当System进程将系统中的关键服务都启动起来之后，ActivityManagerService服务就会通知SurfaceFlinger服务boot Finished接着修改系统属性ctl.stop的值，以便可以通知init进程停止执行应用程序bootanimation。 
android_o/frameworks/native/services/surfaceflinger/surfaceflinger.rc

service surfaceflinger /system/bin/surfaceflinger
     class core animation
     user system
     group graphics drmrpc readproc
     onrestart restart zygote
     writepid /dev/stune/foreground/tasks
     ...

• 服务的入口在main_surfaceflinger.cpp 

主要工作是：新建一个SurfaceFlinger对象，然后调用其中的init()方法，最后调用其中的run()方法。

int main(int, char**) {
80      startHidlServices();
81  
82      signal(SIGPIPE, SIG_IGN);
83      // When SF is launched in its own process, limit the number of
84      // binder threads to 4.
85      ProcessState::self()->setThreadPoolMaxThreadCount(4);
86  
87      // start the thread pool
88      sp<ProcessState> ps(ProcessState::self());
89      ps->startThreadPool();
90  
91      // instantiate surfaceflinger
92      sp<SurfaceFlinger> flinger = new SurfaceFlinger();
93  
94      setpriority(PRIO_PROCESS, 0, PRIORITY_URGENT_DISPLAY);
95  
96      set_sched_policy(0, SP_FOREGROUND);
97  
98      // Put most SurfaceFlinger threads in the system-background cpuset
99      // Keeps us from unnecessarily using big cores
100      // Do this after the binder thread pool init
101      if (cpusets_enabled()) set_cpuset_policy(0, SP_SYSTEM);
102  
103      // initialize before clients can connect
104      flinger->init();
105  
106      // publish surface flinger
107      sp<IServiceManager> sm(defaultServiceManager());
108      sm->addService(String16(SurfaceFlinger::getServiceName()), flinger, false);
109  
110      // publish GpuService
111      sp<GpuService> gpuservice = new GpuService();
112      sm->addService(String16(GpuService::SERVICE_NAME), gpuservice, false);
113  
114      struct sched_param param = {0};
115      param.sched_priority = 2;
116      if (sched_setscheduler(0, SCHED_FIFO, &param) != 0) {
117          ALOGE("Couldn't set SCHED_FIFO");
118      }
119  
120      // run surface flinger in this thread
121      flinger->run();
122  
123      return 0;
124  }

• android_o/frameworks/native/services/surfaceflinger/SurfaceFlinger.cpp 

SurfaceFlinger在init函数最后会创建一个StartBootAnimThread，在这个线程中设置两个属性值：service.bootanim.exit 和 ctl.start。

void SurfaceFlinger::init() {
...
     mStartBootAnimThread = new StartBootAnimThread();
      if (mStartBootAnimThread->Start() != NO_ERROR) {
          ALOGE("Run StartBootAnimThread failed!");
      }

      ALOGV("Done initializing");
  }

bool StartBootAnimThread::threadLoop() {
      property_set("service.bootanim.exit", "0");
      property_set("ctl.start", "bootanim");
      // Exit immediately
      return false;
  }

• bootanim，这样bootanim进程就会启动?在看init进程的init.cpp的main函数中：

int main(int argc, char** argv) {
......
   // At this point we're in the second stage of init.
    InitKernelLogging(argv);
    LOG(INFO) << "init second stage started!";

    // Set up a session keyring that all processes will have access to. It
    // will hold things like FBE encryption keys. No process should override
    // its session keyring.
    keyctl(KEYCTL_GET_KEYRING_ID, KEY_SPEC_SESSION_KEYRING, 1);

    // Indicate that booting is in progress to background fw loaders, etc.
    close(open("/dev/.booting", O_WRONLY | O_CREAT | O_CLOEXEC, 0000));

    property_init();

    // If arguments are passed both on the command line and in DT,
    // properties set in DT always have priority over the command-line ones.
    process_kernel_dt();
    process_kernel_cmdline();

    // Propagate the kernel variables to internal variables
    // used by init as well as the current required properties.
    export_kernel_boot_props();

    // Make the time that init started available for bootstat to log.
    property_set("ro.boottime.init", getenv("INIT_STARTED_AT"));
    property_set("ro.boottime.init.selinux", getenv("INIT_SELINUX_TOOK"));

    // Set libavb version for Framework-only OTA match in Treble build.
    const char* avb_version = getenv("INIT_AVB_VERSION");
    if (avb_version) property_set("ro.boot.avb_version", avb_version);

    // Clean up our environment.
    unsetenv("INIT_SECOND_STAGE");
    unsetenv("INIT_STARTED_AT");
    unsetenv("INIT_SELINUX_TOOK");
    unsetenv("INIT_AVB_VERSION");

    // Now set up SELinux for second stage.
    selinux_initialize(false);
    selinux_restore_context();

    epoll_fd = epoll_create1(EPOLL_CLOEXEC);
    if (epoll_fd == -1) {
        PLOG(ERROR) << "epoll_create1 failed";
        exit(1);
    }

    signal_handler_init();

    property_load_boot_defaults();
    export_oem_lock_status();
    start_property_service(); //start_property_service
    set_usb_controller();

• main函数中start_property_service()，在这个函数中注册一个epoll handle 的机制 register_epoll_handler()：

666  void start_property_service() {
667      property_set("ro.property_service.version", "2");
668  
669      property_set_fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
670                                      0666, 0, 0, NULL);
671      if (property_set_fd == -1) {
672          PLOG(ERROR) << "start_property_service socket creation failed";
673          exit(1);
674      }
675  
676      listen(property_set_fd, 8);
677  
678      register_epoll_handler(property_set_fd, handle_property_set_fd);
679  }

• init进程会使用epoll机制来轮询事件，其中一个事件是系统属性值被修改。得到该事件后，会执行handle_property_set_fd()，代码如下：通过handle_property_set_fd():

static void handle_property_set_fd() {
     ...
     switch (cmd) {
409      case PROP_MSG_SETPROP: {
410          char prop_name[PROP_NAME_MAX];
411          char prop_value[PROP_VALUE_MAX];
412  
413          if (!socket.RecvChars(prop_name, PROP_NAME_MAX, &timeout_ms) ||
414              !socket.RecvChars(prop_value, PROP_VALUE_MAX, &timeout_ms)) {
415            PLOG(ERROR) << "sys_prop(PROP_MSG_SETPROP): error while reading name/value from the socket";
416            return;
417          }
418  
419          prop_name[PROP_NAME_MAX-1] = 0;
420          prop_value[PROP_VALUE_MAX-1] = 0;
421  
422          handle_property_set(socket, prop_value, prop_value, true);
423          break;
424        }

• 该函数会进一步执行handle_control_message()，传入的参数msg.name=ctl.start，msg.value=bootanim

179  void handle_control_message(const std::string& msg, const std::string& name) {
180      Service* svc = ServiceManager::GetInstance().FindServiceByName(name);
181      if (svc == nullptr) {
182          LOG(ERROR) << "no such service '" << name << "'";
183          return;
184      }
185  
186      if (msg == "start") {
187          svc->Start();
188      } else if (msg == "stop") {
189          svc->Stop();
190      } else if (msg == "restart") {
191          svc->Restart();
192      } else {
193          LOG(ERROR) << "unknown control msg '" << msg << "'";
194      }
195  }

• 
  
• 由于msg == “start”，handle_control_message进一步执行msg_start（），且传入的arg参数等于bootanim。msg_start代码如下:

static void msg_start(const char *name)  
{  
    struct service *svc = NULL;  
    char *tmp = NULL;  
    char *args = NULL;  

    if (!strchr(name, ':'))  
        svc = service_find_by_name(name);  
    else {  
        tmp = strdup(name);  
        if (tmp) {  
            args = strchr(tmp, ':');  
            *args = '\0';  
            args++;  

            svc = service_find_by_name(tmp);  
        }  
    }  

    if (svc) {  
        service_start(svc, args);  
    } else {  
        ERROR("no such service '%s'\n", name);  
    }  
    if (tmp)  
        free(tmp);  
}  

• 该函数首先调用service_find_by_name()，从service_list中查询要启动的服务是否有存在，若存在，返回服务的相关信息。因为init.rc中有bootanimation的定义，因此在init进程执行parse_config()时，会将该服务添加到service_list中，所以bootanimation应用是存在的。然后，如果找到了该服务，就调用service_start启动服务。 

到此，bootanimation应用就启动了。

在SurfaceFlinger bootFinshed后重新设置service.bootanim.exit的值，退出bootanim服务

void SurfaceFlinger::bootFinished(){
...
// stop boot animation
// formerly we would just kill the process, but we now ask it to exit so it
// can choose where to stop the animation.
   property_set("service.bootanim.exit", "1");

• 在bootanim的main函数中会通过ServiceManager来检查SurfaceFlinger是否启动，确定SurfaceFlinger启动后会new BootAnimation的实例。

int main()
38  {
39      setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_DISPLAY);
40  
41      char value[PROPERTY_VALUE_MAX];
42      property_get("debug.sf.nobootanimation", value, "0");
43      int noBootAnimation = atoi(value);
44      if (!noBootAnimation) {
45          property_get("ro.boot.quiescent", value, "0");
46          noBootAnimation = atoi(value);
47      }
48      ALOGI_IF(noBootAnimation,  "boot animation disabled");
49      if (!noBootAnimation) {
50  
51          sp proc(ProcessState::self());
52          ProcessState::self()->startThreadPool();
53  
54          // TODO: replace this with better waiting logic in future, b/35253872
55          int64_t waitStartTime = elapsedRealtime();
56          sp sm = defaultServiceManager();
57          const String16 name("SurfaceFlinger");
58          const int SERVICE_WAIT_SLEEP_MS = 100;
59          const int LOG_PER_RETRIES = 10;
60          int retry = 0;
61          while (sm->checkService(name) == nullptr) {
62              retry++;
63              if ((retry % LOG_PER_RETRIES) == 0) {
64                  ALOGW("Waiting for SurfaceFlinger, waited for %" PRId64 " ms",
65                        elapsedRealtime() - waitStartTime);
66              }
67              usleep(SERVICE_WAIT_SLEEP_MS * 1000);
68          };
69          int64_t totalWaited = elapsedRealtime() - waitStartTime;
70          if (totalWaited > SERVICE_WAIT_SLEEP_MS) {
71              ALOGI("Waiting for SurfaceFlinger took %" PRId64 " ms", totalWaited);
72          }
73  
74          // create the boot animation object
75          sp boot = new BootAnimation();
76  
77          IPCThreadState::self()->joinThreadPool();
78      }
79      return 0;
80  }

• 第一次创建BootAnimation的实例引用后进入到onFirstRef()：

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);//启动线程
      }
  }

• 在onFirstRef中启动了线程BootAnimation, 第一次执行会运行线程的readyToRun()方法，再执行threadLoop(),所以先看readyToRun：

status_t BootAnimation::readyToRun() {
    mAssets.addDefaultAssets();

    sp dtoken(SurfaceComposerClient::getBuiltInDisplay(
            ISurfaceComposer::eDisplayIdMain));
    DisplayInfo dinfo;
    status_t status = SurfaceComposerClient::getDisplayInfo(dtoken, &dinfo);
    if (status)
        return -1;
    // create the native surface
    sp control = session()->createSurface(String8("BootAnimation"),
            dinfo.w, dinfo.h, PIXEL_FORMAT_RGB_565);
    SurfaceComposerClient::openGlobalTransaction();
    control->setLayer(0x40000000);
    SurfaceComposerClient::closeGlobalTransaction();

    sp 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;
    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;

    // 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);
    if (!mShuttingDown && encryptedAnimation && (access(
            getAnimationFileName(SYSTEM_ENCRYPTED_BOOTANIMATION_FILE
            ,mShuttingDown),R_OK) == 0)){
        mZipFileName =getAnimationFileName(SYSTEM_ENCRYPTED_BOOTANIMATION_FILE,
                mShuttingDown);
        return NO_ERROR;
    }

    static const char* bootFiles[] = 
            {OEM_BOOTANIMATION_FILE,SYSTEM_BOOTANIMATION_FILE};
    static const char* shutdownFiles[] =
            {OEM_SHUTDOWNANIMATION_FILE, SYSTEM_SHUTDOWNANIMATION_FILE};

    for (const char* f : (!mShuttingDown ? bootFiles : shutdownFiles)) {
        if (access(getAnimationFileName(f,mShuttingDown), R_OK) == 0) {
            mZipFileName = getAnimationFileName(f,mShuttingDown);
            return NO_ERROR;
        }
    }
    return NO_ERROR;
}

• 这里主要做了：

• 为bootnanimation创建native surface
• 初始化 opengl and egl
• 判断是否显示 encrypted boot animation
• 获取AnimationFileName：mZipFileName

BootAnimation类的成员函数session用来返回BootAnimation类的成员变量mSession所描述的一个SurfaceComposerClient对象。通过调用SurfaceComposerClient对象mSession的成员函数createSurface可以获得一个SurfaceControl对象control。

SurfaceComposerClient类的成员函数createSurface首先调用内部的Binder代理对象mClient来请求SurfaceFlinger返回一个类型为SurfaceLayer的Binder代理对象，接着再使用这个Binder代理对象来创建一个SurfaceControl对象。创建出来的SurfaceControl对象的成员变量mSurface就指向了从SurfaceFlinger返回来的类型为SurfaceLayer的Binder代理对象。有了这个Binder代理对象之后，SurfaceControl对象就可以和SurfaceFlinger服务通信了。

调用SurfaceControl对象control的成员函数getSurface会返回一个Surface对象s。这个Surface对象s内部也有一个类型为SurfaceLayer的Binder代理对象mSurface，这个Binder代理对象与前面所创建的SurfaceControl对象control的内部的Binder代理对象mSurface引用的是同一个SurfaceLayer对象。这样，Surface对象s也可以通过其内部的Binder代理对象mSurface来和SurfaceFlinger服务通信。

   Surface类继承了ANativeWindow类。ANativeWindow类是连接OpenGL和Android窗口系统的桥梁，即OpenGL需要通过ANativeWindow类来间接地操作Android窗口系统。这种桥梁关系是通过EGL库来建立的，所有以egl为前缀的函数名均为EGL库提供的接口。

   为了能够在OpenGL和Android窗口系统之间的建立一个桥梁，我们需要一个EGLDisplay对象display，一个EGLConfig对象config，一个EGLSurface对象surface，以及一个EGLContext对象context，其中，EGLDisplay对象display用来描述一个EGL显示屏，EGLConfig对象config用来描述一个EGL帧缓冲区配置参数，EGLSurface对象surface用来描述一个EGL绘图表面，EGLContext对象context用来描述一个EGL绘图上下文（状态），它们是分别通过调用egl库函数eglGetDisplay、EGLUtils::selectConfigForNativeWindow、eglCreateWindowSurface和eglCreateContext来获得的。注意，EGLConfig对象config、EGLSurface对象surface和EGLContext对象context都是用来描述EGLDisplay对象display的。有了这些对象之后，就可以调用函数eglMakeCurrent来设置当前EGL库所使用的绘图表面以及绘图上下文。  

   还有另外一个地方需要注意的是，每一个EGLSurface对象surface有一个关联的ANativeWindow对象。这个ANativeWindow对象是通过函数eglCreateWindowSurface的第三个参数来指定的。在我们这个场景中，这个ANativeWindow对象正好对应于前面所创建的 Surface对象s。每当OpenGL需要绘图的时候，它就会找到前面所设置的绘图表面，即EGLSurface对象surface。有了EGLSurface对象surface之后，就可以找到与它关联的ANativeWindow对象，即Surface对象s。有了Surface对象s之后，就可以通过其内部的Binder代理对象mSurface来请求  SurfaceFlinger服务返回帧缓冲区硬件设备的一个图形访问接口。这样，OpenGL最终就可以将要绘制的图形渲染到帧缓冲区硬件设备中去，即显示在实际屏幕上。屏幕的大小，即宽度和高度，可以通过函数eglQuerySurface来获得。

线程的首次准备工作在这里完成后，开始执行threadLoop()： 
threadLoop()函数如果返回值为false，则该函数中的内容只会执行一次；如果返回true，则会不停的执行。这里返回false，因此只会执行一次。

bool BootAnimation::threadLoop()
{
    bool r;
    // We have no bootanimation file, so we use the stock android logo
    // animation.
    if (mZipFileName.isEmpty()) {
        r = android();
    } else {
        r = movie();
    }

    eglMakeCurrent(mDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
    eglDestroyContext(mDisplay, mContext);
    eglDestroySurface(mDisplay, mSurface);
    mFlingerSurface.clear();
    mFlingerSurfaceControl.clear();
    eglTerminate(mDisplay);
    eglReleaseThread();
    IPCThreadState::self()->stopProcess();
    return r;
}

• 
  
• 如果我们没有自己的bootanimation文件name就执行android()，否则执行movie()。

这里我们关注的是自己的bootanimation文件的播放，来看movie()：

bool BootAnimation::movie()
{
    Animation* animation = loadAnimation(mZipFileName);
    if (animation == NULL)
        return false;

    ......

    playAnimation(*animation);  //播放Animation

    ......
}

• 首先movies()进行loadAnimation ; 然后在movies()中执行playAnimation

先看loadAnimation():

BootAnimation::Animation* BootAnimation::loadAnimation(const String8& fn)
{
    if (mLoadedFiles.indexOf(fn) >= 0) {
        ALOGE("File \"%s\" is already loaded. Cyclic ref is not allowed",
            fn.string());
        return NULL;
    }
    ZipFileRO *zip = ZipFileRO::open(fn);
    if (zip == NULL) {
        ALOGE("Failed to open animation zip \"%s\": %s",
            fn.string(), strerror(errno));
        return NULL;
    }

    Animation *animation =  new Animation;
    animation->fileName = fn;
    animation->zip = zip;
    animation->clockFont.map = nullptr;
    mLoadedFiles.add(animation->fileName);

    parseAnimationDesc(*animation);
    if (!preloadZip(*animation)) {
        return NULL;
    }


    mLoadedFiles.remove(fn);
    return animation;
}

• 
  
• 这里两个重要的事情parseAnimationDesc和preloadZip

parseAnimationDesc是解析描述文件desc.txt并保存在animation对象中, 这个文件打包在bootanimation.zip中如下所示：

而preloadZip,下面这段代码是读取每个片段中的png图片，并保存在animation.parts.frames中。

bool BootAnimation::preloadZip(Animation& animation)
{
    // read all the data structures
    const size_t pcount = animation.parts.size();
    void *cookie = NULL;
    ZipFileRO* zip = animation.zip;
    ......

    Animation::Part* partWithAudio = NULL;
    ZipEntryRO entry;
    char name[ANIM_ENTRY_NAME_MAX];
    while ((entry = zip->nextEntry(cookie)) != NULL) {
        const int foundEntryName = zip->getEntryFileName(entry, name, ANIM_ENTRY_NAME_MAX);
        if (foundEntryName > ANIM_ENTRY_NAME_MAX || foundEntryName == -1) {
            ALOGE("Error fetching entry file name");
            continue;
        }

        const String8 entryName(name);
        const String8 path(entryName.getPathDir());
        const String8 leaf(entryName.getPathLeaf());
        if (leaf.size() > 0) {
            if (entryName == CLOCK_FONT_ZIP_NAME) {
                FileMap* map = zip->createEntryFileMap(entry);
                if (map) {
                    animation.clockFont.map = map;
                }
                continue;
            }

            for (size_t j = 0; j < pcount; j++) {
                if (path == animation.parts[j].path) {
                    uint16_t method;
                    // supports only stored png files
                    if (zip->getEntryInfo(entry, &method, NULL, NULL, NULL, NULL, NULL)) {
                        if (method == ZipFileRO::kCompressStored) {
                            FileMap* map = zip->createEntryFileMap(entry);
                            if (map) {
                                Animation::Part&
                                         part(animation.parts.editItemAt(j));
                                if (leaf == "audio.wav") {
                                    // a part may have at most one audio file
                                    part.audioData = (uint8_t *)map
                                            ->getDataPtr();
                                    part.audioLength = map->getDataLength();
                                    partWithAudio = ∂
                                } else if (leaf == "trim.txt") {
                                    part.trimData.setTo((char const*)map
                                            ->getDataPtr(), map
                                            ->getDataLength());
                                } else {
                                    Animation::Frame frame;
                                    frame.name = leaf;
                                    frame.map = map;
                                    frame.trimWidth = animation.width;
                                    frame.trimHeight = animation.height;
                                    frame.trimX = 0;
                                    frame.trimY = 0;
                                    part.frames.add(frame);
                                }
                            }
                        } else {
                            ALOGE("bootanimation.zip is compressed; must be only stored");
                        }
                    }
                }
            }
        }
    }

    // If there is trimData present, override the positioning defaults.
    for (Animation::Part& part : animation.parts) {
        const char* trimDataStr = part.trimData.string();
        for (size_t frameIdx = 0; frameIdx < part.frames.size(); frameIdx++) {
            const char* endl = strstr(trimDataStr, "\n");
            // No more trimData for this part.
            if (endl == NULL) {
                break;
            }
            String8 line(trimDataStr, endl - trimDataStr);
            const char* lineStr = line.string();
            trimDataStr = ++endl;
            int width = 0, height = 0, x = 0, y = 0;
            if (sscanf(lineStr, "%dx%d+%d+%d", &width, &height, &x, &y) == 4) {
                Animation::Frame& frame(part.frames.editItemAt(frameIdx));
                frame.trimWidth = width;
                frame.trimHeight = height;
                frame.trimX = x;
                frame.trimY = y;
            } else {
                ALOGE("Error parsing trim.txt, line: %s", lineStr);
                break;
            }
        }
    }

    // Create and initialize audioplay if there is a wav file in any of the animations.
    // Do it on a separate thread so we don't hold up the animation intro.
    if (partWithAudio != NULL) {
        ALOGD("found audio.wav, creating playback engine");
        mInitAudioThread = new InitAudioThread(partWithAudio->audioData,
                                               partWithAudio->audioLength);
        mInitAudioThread->run("BootAnimation::InitAudioThread", PRIORITY_NORMAL);
    }

    zip->endIteration(cookie);

    return true;
}

• 可以看到animation中如果有audio.wav会被解析保存在part.audioData，开机时进行播放。audio.wav可以放到part0中。

解析完成后返回animation给playAnimation()进行播放

loadAnimation完成接着playAnimation():

bool BootAnimation::playAnimation(const Animation& animation)
{
    const size_t pcount = animation.parts.size();
    nsecs_t frameDuration = s2ns(1) / animation.fps;
    const int animationX = (mWidth - animation.width) / 2;
    const int animationY = (mHeight - animation.height) / 2;

    ALOGD("%sAnimationShownTiming start time: %" PRId64 "ms", mShuttingDown ? "Shutdown" : "Boot",
            elapsedRealtime());
    for (size_t i=0 ; iconst Animation::Part& part(animation.parts[i]);
        const size_t fcount = part.frames.size();
        glBindTexture(GL_TEXTURE_2D, 0);

        // Handle animation package
        if (part.animation != NULL) {
            playAnimation(*part.animation);
            if (exitPending())
                break;
            continue; //to next part
        }

        for (int r=0 ; !part.count || r// Exit any non playuntil complete parts immediately
            if(exitPending() && !part.playUntilComplete)
                break;

            // only play audio file the first time we animate the part
            if (r == 0 && part.audioData && playSoundsAllowed()) {
                ALOGD("playing clip for part%d, size=%d", (int) i, part.audioLength);
                // Block until the audio engine is finished initializing.
                if (mInitAudioThread != nullptr) {
                    mInitAudioThread->join();
                }
                audioplay::playClip(part.audioData, part.audioLength);
            }

            glClearColor(
                    part.backgroundColor[0],
                    part.backgroundColor[1],
                    part.backgroundColor[2],
                    1.0f);

            for (size_t j=0 ; jconst 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);
                    }
                    int w, h;
                    initTexture(frame.map, &w, &h);
                }

                const int xc = animationX + frame.trimX;
                const int yc = animationY + frame.trimY;
                Region clearReg(Rect(mWidth, mHeight));
                clearReg.subtractSelf(Rect(xc, yc, xc+frame.trimWidth, yc+frame.trimHeight));
                if (!clearReg.isEmpty()) {
                    Region::const_iterator head(clearReg.begin());
                    Region::const_iterator tail(clearReg.end());
                    glEnable(GL_SCISSOR_TEST);
                    while (head != tail) {
                        const Rect& r2(*head++);
                        glScissor(r2.left, mHeight - r2.bottom, r2.width(), r2.height());
                        glClear(GL_COLOR_BUFFER_BIT);
                    }
                    glDisable(GL_SCISSOR_TEST);
                }
                // specify the y center as ceiling((mHeight - frame.trimHeight) / 2)
                // which is equivalent to mHeight - (yc + frame.trimHeight)
                glDrawTexiOES(xc, mHeight - (yc + frame.trimHeight),
                              0, frame.trimWidth, frame.trimHeight);
                if (mClockEnabled && mTimeIsAccurate && validClock(part)) {
                    drawClock(animation.clockFont, part.clockPosX, part.clockPosY);
                }

                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 textures created for looping parts now that the animation is done.
    for (const Animation::Part& part : animation.parts) {
        if (part.count != 1) {
            const size_t fcount = part.frames.size();
            for (size_t j = 0; j < fcount; j++) {
                const Animation::Frame& frame(part.frames[j]);
                glDeleteTextures(1, &frame.tid);
            }
        }
    }

    // we've finally played everything we're going to play
    audioplay::setPlaying(false);
    audioplay::destroy();

    return true;
}

• exitPending()—如果SurfaceFlinger服务通知bootanimation停止显示动画，则该函数返回值为true，否则为false

WMS通知关闭开机动画

当System进程将系统中的关键服务启动起来之后，就会将应用程序启动器（Launcher）启动起来。 一个Activity组件在启动起来之后，就会被记录起来，等到它所运行在的主线程空闲的时候，这个主线程就会向ActivityManagerService发送一个Activity组件空闲的通知。由于应用程序Launcher是系统中第一个被启动的应用程序，即它的根Activity组件是系统中第一个被启动的Activity组件，因此，当ActivityManagerService接收到它的空闲通知的时候，就可以知道系统是刚刚启动起来的。在这种情况下，ActivityManagerService收到消息FINISH_BOOTING_MSG，调用AMS的enableScreenAfterBoot方法，这样才能停止显示开机动画，以便可以在屏幕中显示应用程序Lancher的界面。

enableScreenAfterBoot()

    void enableScreenAfterBoot() {
          EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_ENABLE_SCREEN,
                  SystemClock.uptimeMillis());
          mWindowManager.enableScreenAfterBoot();

          synchronized (this) {
              updateEventDispatchingLocked();
          }
      }

• 在WMS的enableScreenAfterBoot方法中又会调用performEnableScreen方法

    private void performEnableScreen() {
        synchronized(mWindowMap) {
        ...
            if (mDisplayEnabled) {
                return;
            }
            if (!mSystemBooted && !mShowingBootMessages) {
                return;
            }

            if (!mShowingBootMessages && !mPolicy.canDismissBootAnimation()) {
                return;
            }

            // Don't enable the screen until all existing windows have been drawn.
            if (!mForceDisplayEnabled
                    // TODO(multidisplay): Expand to all displays?
                    && getDefaultDisplayContentLocked().checkWaitingForWindows()) {
                return;
            }

            if (!mBootAnimationStopped) {
                // Do this one time.
                Trace.asyncTraceBegin(TRACE_TAG_WINDOW_MANAGER, "Stop bootanim", 0);
                try {
                    IBinder surfaceFlinger = 
                           ServiceManager.getService("SurfaceFlinger");
                    if (surfaceFlinger != null) {
                        Parcel data = Parcel.obtain();
                        data.writeInterfaceToken("android.ui.ISurfaceComposer");
                       // BOOT_FINISHED
                        surfaceFlinger.transact(IBinder.FIRST_CALL_TRANSACTION, 
                                data, null, 0);
                        data.recycle();
                    }
                } catch (RemoteException ex) {
                    Slog.e(TAG_WM, "Boot completed: SurfaceFlinger is dead!");
                }
                mBootAnimationStopped = true;
            }
            ......
            EventLog.writeEvent(EventLogTags.WM_BOOT_ANIMATION_DONE, 
                    SystemClock.uptimeMillis());
            Trace.asyncTraceEnd(TRACE_TAG_WINDOW_MANAGER, "Stop bootanim", 0);
            mDisplayEnabled = true;
            if (DEBUG_SCREEN_ON || DEBUG_BOOT) Slog.i(TAG_WM, 
                    "******************** ENABLING SCREEN!");

            // Enable input dispatch.
            mInputMonitor.setEventDispatchingLw(mEventDispatchingEnabled);
        }

        try {
            mActivityManager.bootAnimationComplete();
        } catch (RemoteException e) {
        }

        mPolicy.enableScreenAfterBoot();

        // Make sure the last requested orientation has been applied.
        updateRotationUnchecked(false, false);
    }

• WMS的performEnableScreen方法，通过Binder调用SurfaceFlinger的transact的FIRST_CALL_TRANSACTION,通过mActivityManager.bootAnimationComplete()去执行finishBooting(）方法：

// Let system services know.          mSystemServiceManager.startBootPhase(SystemService.PHASE_BOOT_COMPLETED);

• 1

最后会在SurfaceFlinger的bootFinshed函数中设置service.bootanim.exit属性为1，这个后面会决定bootanim进程什么时候关闭。

void SurfaceFlinger::bootFinished(){
...
// stop boot animation
// formerly we would just kill the process, but we now ask it to exit so it
// can choose where to stop the animation.
   property_set("service.bootanim.exit", "1");

• 关机动画和铃声

动画以及铃声定制

开机动画：

1) 制作bootanimation.zip。制作方法举例如下： 
分别创建名为“part0”和“part1”的文件夹以及一个名为“desc.txt”文件。“part0”中存储动画的第一阶段的资源图片，“part1”存储第二阶段的资源图片，注意图片为png格式。

  desc.txt文件由若干行组成，每一行代表一种描述

播放控制由“desc.txt”指定，内容如下： 
720 1080 30 
p 1 0 part0 
p 0 0 part1 
c 0 0 part2 
c 1 0 part3

各参数功能如下： ( 注意：desc.txt文本内容必须用单个空格隔开，且不能有多余空行。)

720	1080	30
宽	高	每秒播放帧数
p	1	0	part0
标志符	循环次数	阶段切换间隔时间	对应目录名
p	0	0	part1
标志符	循环次数	阶段切换间隔时间	对应目录名

第1行：用来描述开机动画在屏幕显示的大小及速度。具体为：开机动画的宽度为720个像素，高度为1080个像素，显示频率为每秒30帧，即每帧显示1/30秒

下面的每一行代表一个片段，显示的时候会按照顺序从上到下依次显示。 
第1个字符为片段类型，有’c’和’p’两种 
第2个数字为该片段重复显示的次数，如果为‘0’，表示会无限重复显示； 
第3个数字为两次显示之间的间隔，单位为第一行中定义的每帧显示的时间； 
第4个字符串为该片段所在的文件夹，一个片段可以由多个png图片组成，都存放在folder文件夹中

例如：

“c 0 0 part2”代表该片段无限循环显示，且两次显示的间隔为0s，与下一个片段间隔0s，该片段的显示图路径为bootanimation.zip/part2。

若exitPending()返回值为true，即SurfaceFlinger服务要求bootanimation停止显示动画，则不管当前显示到哪个片段或png图片，都会导致退出for循环，从而停止开机动画的显示。 
在Android5.1中，加入了“c”片段。对与以”c”标识的片段，即使exitPending()返回值为true，也会继续显示。 
这一点在BootAnimation::parseAnimationDesc中可以看到：

        if (sscanf(l, "%d %d %d", &width, &height, &fps) == 3) {
            ALOGD("> w=%d, h=%d, fps=%d", width, height, fps);
            animation.width = width;
            animation.height = height;
            animation.fps = fps;
        } else if (sscanf(l, " %c %d %d %s #%6s %16s %16s",
               &pathType, &count, &pause, path, color, clockPos1, 
               clockPos2) >= 4) {
            ALOGD("> type=%c, count=%d, pause=%d, path=%s, color=%s,    
                    clockPos1=%s, clockPos2=%s",pathType, count, pause,  
                    path, color, clockPos1, clockPos2);
            Animation::Part part;
            part.playUntilComplete = pathType == 'c';
            part.count = count;
            part.pause = pause;
            part.path = path;
            part.audioData = NULL;
            part.animation = NULL;

• 最后，将这5个组件通过存储压缩的方式压缩为bootanimation.zip文件即制作完成。

2) 预置开机动画。预置的过程如下： 
将制作完成的bootanimation.zip文件放在工程的资源目录下

添加开机铃声：

方案一：animation.zip

直接在animation.zip包中的part0目录下放上audio.wav文件，animation.zip如果解析出audio.wav会保存在保存在animation的part.audioData中给系统播放。注意需要为wav文件

方案二：使用MediaPlay实现的思路

1 先将要设置为铃声的音乐文件更名为bootaudio.mp3,注意需要为mp3文件。

2 将该文件放入工程的资源目录下，如frameworks\base\data\sounds\newwavelabs， 
修改Android.mk文件，将该文件编译到system\media\路径下，添加如下语句：

 $(LOCAL_PATH)/newwavelabs/bootaudio.mp3:system/media/bootaudio.mp3

• 3 修改 Makefile文件

LOCAL_SHARED_LIBRARIES += \  
    libmedia  

• 修改BootAnimation.cpp 

添加：

#include <system/audio.h>  


bool BootAnimation :: soundplay()  
{  
    mfd = open(xxxxx, O_RDONLY); //xxxxx为音乐文件  

    mp = new MediaPlayer();  
    mp->setDataSource(mfd, 0, 0x7ffffffffffffffLL);  
    mp->setAudioStreamType(/*AUDIO_STREAM_MUSIC*/AUDIO_STREAM_SYSTEM);  
    mp->prepare();  
    mp->start();  
}  

bool BootAnimation::soundstop()  
{  
    if (mp != NULL)   
        mp->stop();  
}  

• 在BootAnimation playAnimation时或者threadloop时进行播放；动画播放完movies()执行完停止播放。

例如：

#include 
#include 


bool BootAnimation::threadLoop()
{
    bool r;
    //声明MediaPlayer变量
    sp mediaplayer;
    const char* resourcePath = initAudioPath();
    status_t mediastatus = NO_ERROR;
    if (resourcePath != NULL) {
        bPlayMP3 = true;
        ALOGD("sound file path: %s", resourcePath);
        mediaplayer = new MediaPlayer();//创建MediaPlayer实例
        mediastatus = mediaplayer->setDataSource(NULL, resourcePath, NULL);

        sp listener = new BootVideoListener(this);
        mediaplayer->setListener(listener);

        if (mediastatus == NO_ERROR) {
            ALOGD("mediaplayer is initialized");
            Parcel* attributes = new Parcel();
            attributes->writeInt32(AUDIO_USAGE_MEDIA);            
            //usage
            attributes->writeInt32(AUDIO_CONTENT_TYPE_MUSIC);    
            //audio_content_type_t
            attributes->writeInt32(AUDIO_SOURCE_DEFAULT);   
            //audio_source_t
            attributes->writeInt32(0);   
            //audio_flags_mask_t
            attributes->writeInt32(1);  
            //kAudioAttributesMarshallTagFlattenTags of mediaplayerservice.cpp
            attributes->writeString16(String16("BootAnimationAudioTrack")); // tags
            mediaplayer->setParameter(KEY_PARAMETER_AUDIO_ATTRIBUTES, *attributes);
            mediaplayer->setAudioStreamType(AUDIO_STREAM_MUSIC);
            mediastatus = mediaplayer->prepare();
        }
        if (mediastatus == NO_ERROR) {
            ALOGD("media player is prepared");
            mediastatus = mediaplayer->start();
        }

    }else{
        bPlayMP3 = false;
    }

    if ((mZip == NULL)&&(mZipFileName.isEmpty())) {
        r = android();
    } else if(mZip != NULL){
        if (!bETC1Movie) {
            ALOGD("threadLoop() movie()");
            r = movie();
        } else {
            ALOGD("threadLoop() ETC1movie()");
            r = ETC1movie();
        }
    }
    else
    {
        r = android();
    }

    if (resourcePath != NULL) {
        if (mediastatus == NO_ERROR) {
            ALOGD("mediaplayer was stareted successfully, now it is 
                    going to be stoped");
            mediaplayer->stop();
            mediaplayer->disconnect();
            mediaplayer.clear();
        }
    }
    eglMakeCurrent(mDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
    eglDestroyContext(mDisplay, mContext);
    eglDestroySurface(mDisplay, mSurface);
    mFlingerSurface.clear();
    mFlingerSurfaceControl.clear();
    eglTerminate(mDisplay);
    eglReleaseThread();
    IPCThreadState::self()->stopProcess();
    return r;
}

BootAnimation::~BootAnimation() {

    if (mZip != NULL) {
        delete mZip;
    }

    if (mProgram) {
        ALOGD("mProgram: %d", mProgram);
        glDeleteProgram(mProgram);
    }
}

BootVideoListener::BootVideoListener(const sp &bootanim) {
    ALOGD("[BootAnimation %s %d]",__FUNCTION__,__LINE__);
    mBootanim = bootanim;
}

BootVideoListener::~BootVideoListener() {
    ALOGD("[BootAnimation %s %d]",__FUNCTION__,__LINE__);
}

void BootVideoListener::notify(int msg, int ext1, int ext2, const Parcel  
       *obj) {
    ALOGD("[BootAnimation %s %d] msg=%d ext1=%d ext2=%d",
            __FUNCTION__,__LINE__, msg, ext1, ext2);
    if(msg == MEDIA_PLAYBACK_COMPLETE || msg == MEDIA_SEEK_COMPLETE) {
        mBootanim->setBootVideoPlayState(MEDIA_PLAYBACK_COMPLETE);
        ALOGD("[BootAnimation %s %d] media player 
                complete",__FUNCTION__,__LINE__);
    }
    if(msg == MEDIA_ERROR || msg == MEDIA_SKIPPED) {
        mBootanim->setBootVideoPlayState(MEDIA_ERROR);
        ALOGD("[BootAnimation %s %d] media player error",__FUNCTION__,__LINE__);
    }

    if(obj == NULL){
        ALOGD("[BootAnimation %s %d]obj is null \n",__FUNCTION__,__LINE__);
    }
}

void BootAnimation::setBootVideoPlayState(int playState){
    mBootVideoPlayState = playState;
    ALOGD("[BootAnimation %s %d]mBootVideoPlayState=%d",
            __FUNCTION__,__LINE__, mBootVideoPlayState);
}