Android 开机动画流程

参考链接：http://www.mamicode.com/info-detail-399016.html

1.启动surfaceflinger

service surfaceflinger /system/bin/surfaceflinger    class core    user system    group graphics drmrpc    onrestart restart zygote

// 根据UTC信息，可大致计算启动surfaceflinger的时间是：2016-06-05 21:14:15.231112
<13>[    4.500719] (0)[1:init]init: starting 'surfaceflinger'
<7>[    4.500893] (0)[1:init][1:init] fork [206:init]
<14>[    4.500993] (0)[1:init]init: PropSet [init.svc.surfaceflinger:running] Start>>
<14>[    4.501033] (0)[1:init]init: PropSet [init.svc.surfaceflinger:running] Done
<4>[   20.774432][thread:129][RT:20764482924] 2016-06-05 13:14:31.504825 UTC; android time 2016-06-05 21:14:31.504825

2.surfaceflinger启动bootanimation

在它的init方法中通过ctl.start的方式启动bootanim。

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

log信息：

// SurfaceFlinger started

06-05 13:14:15.917427   206   206 I SurfaceFlinger: SurfaceFlinger is starting
06-05 13:14:15.917584   206   206 I SurfaceFlinger: SurfaceFlinger's main thread ready to run. Initializing graphics H/W...
// init start bootanimation
<14>[    5.865806] (2)[1:init]init: [PropSet]: pid:206 uid:1000 gid:1003 set service.bootanim.exit=0
<14>[    5.865817] (2)[1:init]init: PropSet [service.bootanim.exit:0] Start>>
<14>[    5.865895] (2)[1:init]init: PropSet [service.bootanim.exit:0] Done
<14>[    5.866460] (2)[1:init]init: [PropSet]: pid:206 uid:1000 gid:1003 ctl.start bootanim
<14>[    5.866605] (2)[1:init]init: computing context for service '/system/bin/bootanimation'
<13>[    5.866724] (2)[1:init]init: starting 'bootanim'
<7>[    5.866838] (2)[1:init][1:init] fork [619:init]
<14>[    5.866903] (2)[1:init]init: PropSet [init.svc.bootanim:running] Start>>
<14>[    5.866982] (2)[1:init]init: PropSet [init.svc.bootanim:running] Done
// bootanimation started
06-05 13:14:16.605907   206   206 I SurfaceFlinger: [void android::SurfaceFlinger::checkEnableBootAnim()] boot reason = '0'
06-05 13:14:16.607570   206   206 I boot    : BOOTPROF:BootAnimation:Start:5842
06-05 13:14:16.723475   619   619 D BootAnimation: [BootAnimation frameworks/base/cmds/bootanimation/bootanimation_main.cpp main 41]start Jan 19 2015 12:00:29

3. bootanimation何时退出

bootanimation进入循环播放动画过程，但每次循环都会去检查是否需要退出。

也就是退出的方式是service.bootanim.exit这个系统属性被set为非0

#define EXIT_PROP_NAME "service.bootanim.exit"void BootAnimation::checkExit() {    // Allow surface flinger to gracefully request shutdown    char value[PROPERTY_VALUE_MAX];    property_get(EXIT_PROP_NAME, value, "0");    int exitnow = atoi(value);    if (exitnow) {        requestExit();    }}// Threads.cppvoid Thread::requestExit(){    Mutex::Autolock _l(mLock);    mExitPending = true;}bool Thread::exitPending() const{    Mutex::Autolock _l(mLock);    return mExitPending;}

log信息：

// 从pid为206可以看到，还是surfaceflinger来关闭bootanim的
// 2016-06-05 21:14:33.204018
<14>[   22.473645] (0)[1:init]init: [PropSet]: pid:206 uid:1000 gid:1003 set service.bootanim.exit=1
<14>[   22.473663] (0)[1:init]init: PropSet [service.bootanim.exit:1] Start>>
<14>[   22.473756] (0)[1:init]init: PropSet [service.bootanim.exit:1] Done
<4>[   22.474564] (2)[433:Binder_2]BOOTPROF:     22474.555539:BOOT_Animation:END
<4>[   20.804432][thread:130][RT:20794464385] 2016-06-05 13:14:31.534805 UTC; android time 2016-06-05 21:14:31.534805

4.谁触发surfaceflinger关闭bootanim？

是WMS通过IPC调用surfaceflinger的bootFinished()方法关闭bootanim。

//WindowManagerService.javapublic void performEnableScreen() {... ...IBinder surfaceFlinger = ServiceManager.getService("SurfaceFlinger");if (surfaceFlinger != null) {Parcel data = Parcel.obtain();data.writeInterfaceToken("android.ui.ISurfaceComposer");surfaceFlinger.transact(IBinder.FIRST_CALL_TRANSACTION, // BOOT_FINISHED        data, null, 0);data.recycle();}mActivityManager.bootAnimationComplete();... ...}

//06-05 21:14:33.213177   206   433 I SurfaceFlinger: Boot is finished (17295 ms)void SurfaceFlinger::bootFinished(){    const nsecs_t now = systemTime();    const nsecs_t duration = now - mBootTime;    ALOGI("Boot is finished (%ld ms)", long(ns2ms(duration)) );    property_set("service.bootanim.exit", "1");}

5.谁触发WMS关闭bootanim？
ActivityThread.java中的Idler的queueIdle()被调用时，会触发。一般地，这个ActivityThread的实例是Launcher的。

// ActivityThread.javaprivate class Idler implements MessageQueue.IdleHandler {    public final boolean queueIdle() {        IActivityManager am = ActivityManagerNative.getDefault();        am.activityIdle(a.token, a.createdConfig, stopProfiling);    }}mStackSupervisor.activityIdleInternalLocked(token, false, config);mService.postFinishBooting(booting, enableScreen);enableScreenAfterBoot()mWindowManager.enableScreenAfterBoot();performEnableScreen();

6.最关键是何时Idler的queueIdle()会被调用

// ActivityThread.javahandleResumeActivityLooper.myQueue().addIdleHandler(new Idler());// MessageQueue.javanext()// If first time idle, then get the number of idlers to run.// Idle handles only run if the queue is empty or if the first message// in the queue (possibly a barrier) is due to be handled in the future.

关于此部分，不懂。