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android开机动画启动流程

时间： 2014-12-31 18:34:49

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从android的Surface Flinger服务启动分析知道，开机动画是在SurfaceFlinger实例通过调用startBootAnim()启动的。

下面我们就一起学习BootAnim是如何启动和结束的，我精读代码前都喜欢先描出框架图，以此图为基础再去研读会达到事半功倍的效果。好吧，直接上图。





内核起来后会启动第一个进程，即init进程。

init进程会根据init.rc配置启动surfaceflinger进程。


[cpp] view plain copy
  1. servicesurfaceflinger/system/bin/surfaceflinger
  2. classmain
  3. usersystem
  4. groupgraphicsdrmrpc
  5. onrestartrestartzygote

surfaceflinger进程便启动了，跟着就会跑进程的main()函数。


frameworks/native/services/surfaceflinger/main_surfaceflinger.cpp

[cpp] view plain copy
  1. intmain(intargc,char**argv){
  2. ....
  4. //instantiatesurfaceflinger
  5. sp<SurfaceFlinger>flinger=newSurfaceFlinger();//创建surfaceflinger服务实例
  7. ....
  8. flinger->init();
  10. //publishsurfaceflinger
  11. sp<IServiceManager>sm(defaultServiceManager());
  12. sm->addService(String16(SurfaceFlinger::getServiceName()),flinger,false);//注册到servicemanager里
  14. //runinthisthread
  15. flinger->run();//开跑
  17. return0;
  18. }

首先new一个SurfaceFlinger实例，然后init，然后run


frameworks/native/services/surfaceflinger/SurfaceFlinger.cpp

[cpp] view plain copy
  1. voidSurfaceFlinger::init(){
  2. ALOGI("SurfaceFlinger'smainthreadreadytorun."
  3. "InitializinggraphicsH/W...");
  5. .....
  6. //startbootanimation
  7. startBootAnim();//开始播放动画
  8. }

初始化graphics之后，就调用startBootAnim()播放开机动画。


[cpp] view plain copy
  1. voidSurfaceFlinger::startBootAnim(){
  2. //startbootanimation
  3. mBootFinished=false;
  4. property_set("service.bootanim.exit","0");//这个会有bootanimation进程周期检测,=1退出动画
  5. property_set("ctl.start","bootanim");//通过ctl.start命令启动bootanim
  6. }

把service.bootanim.exit属性设为0，这个属性bootanimation进程里会周期检查，=1时就退出动画，这里=0表示要播放动画。

后面通过ctl.start的命令启动bootanim进程，动画就开始播放了。


下面来到bootanimation的实现


frameworks/base/cmds/bootanimation/bootanimation_main.cpp

[cpp] view plain copy
  1. intmain(intargc,char**argv)
  2. {
  5. sp<ProcessState>proc(ProcessState::self());
  6. ProcessState::self()->startThreadPool();
  8. //createthebootanimationobject
  9. sp<BootAnimation>boot=newBootAnimation();//创建BootAnimation实例
  11. IPCThreadState::self()->joinThreadPool();//binder线程池，与surfaceflinger通信用的。
  13. }
  14. return0;
  15. }

new一个BootAnimation实例,然后建个binder线程池，因为BootAnimation在显示动画时要与SurfaceFlinger服务进程通信，所以要启个binder线程池。


frameworks/base/cmds/bootanimation/BootAnimation.cpp

[cpp] view plain copy
  1. BootAnimation::BootAnimation():Thread(false)
  2. {
  3. mSession=newSurfaceComposerClient();//创建一个对象
  4. }

创建实例时，构造函数就会被调用，new一个SurfaceComposerClient实例，他是用来与surfaceflinger通信的


[cpp] view plain copy
  1. voidBootAnimation::onFirstRef(){
  2. status_terr=mSession->linkToComposerDeath(this);//注册surfaceflinger死亡消息的通知书
  3. ALOGE_IF(err,"linkToComposerDeathfailed(%s)",strerror(-err));
  4. if(err==NO_ERROR){
  5. run("BootAnimation",PRIORITY_DISPLAY);//开跑
  6. }
  7. }


linkTocomposerDeath的作用是当surfaceflinger死掉是，BootAnimation就会得到通知。


如下，收到通知后就退出动画了，因为surfaceflinger都挂掉了，播放不了了。

[cpp] view plain copy
  1. voidBootAnimation::binderDied(constwp<IBinder>&who)
  2. {
  3. //woah,surfaceflingerdied!
  4. ALOGD("SurfaceFlingerdied,exiting...");
  6. //callingrequestExit()isnotenoughherebecausetheSurfacecode
  7. //mightbeblockedonaconditionvariablethatwillneverbeupdated.
  8. kill(getpid(),SIGKILL);//收到surfaceflinger死亡的消息，好吧自己也跟着去了。
  9. requestExit();
  10. }

另一个函数run()在BootAnimation的父类Thead里，用来创建一个线程并跑起来。


父类

system/core/libutils/Threads.cpp

[cpp] view plain copy
  1. status_tThread::run(constchar*name,int32_tpriority,size_tstack)
  2. {
  3. ...
  5. if(mCanCallJava){
  6. res=createThreadEtc(_threadLoop,//创建线程
  7. this,name,priority,stack,&mThread);
  8. }else{
  9. res=androidCreateRawThreadEtc(_threadLoop,
  10. this,name,priority,stack,&mThread);
  11. }
  12. ....
  13. }

创建_threadLoop线程

[cpp] view plain copy
  1. intThread::_threadLoop(void*user)
  2. {
  3. ....
  4. do{
  5. boolresult;
  6. if(first){
  7. first=false;
  8. self->mStatus=self->readyToRun();//这个函数被bootanimation重写了
  9. result=(self->mStatus==NO_ERROR);
  11. if(result&&!self->exitPending()){
  12. ...
  13. result=self->threadLoop();//这个函数被bootanimation重写了
  14. }
  15. }else{
  16. result=self->threadLoop();
  17. }
  19. ...
  21. return0;
  22. }

readyToRun函数实现

[cpp] view plain copy
  1. status_tBootAnimation::readyToRun(){
  2. mAssets.addDefaultAssets();
  4. sp<IBinder>dtoken(SurfaceComposerClient::getBuiltInDisplay(
  5. ISurfaceComposer::eDisplayIdMain));
  6. DisplayInfodinfo;
  7. status_tstatus=SurfaceComposerClient::getDisplayInfo(dtoken,&dinfo);
  8. if(status)
  9. return-1;
  10. charvalue[PROPERTY_VALUE_MAX];
  11. property_get("persist.panel.orientation",value,"0");
  12. intorient=atoi(value)/90;
  14. if(orient==eOrientation90||orient==eOrientation270){
  15. inttemp=dinfo.h;
  16. dinfo.h=dinfo.w;
  17. dinfo.w=temp;
  18. }
  20. RectdestRect(dinfo.w,dinfo.h);
  21. mSession->setDisplayProjection(dtoken,orient,destRect,destRect);
  23. //createthenativesurface
  24. sp<SurfaceControl>control=session()->createSurface(String8("BootAnimation"),
  25. dinfo.w,dinfo.h,PIXEL_FORMAT_RGB_565);
  27. SurfaceComposerClient::openGlobalTransaction();
  28. control->setLayer(0x40000000);
  29. SurfaceComposerClient::closeGlobalTransaction();
  31. sp<Surface>s=control->getSurface();
  33. //initializeopenglandegl
  34. constEGLintattribs[]={
  35. EGL_RED_SIZE,8,
  36. EGL_GREEN_SIZE,8,
  37. EGL_BLUE_SIZE,8,
  38. EGL_DEPTH_SIZE,0,
  39. EGL_NONE
  40. };
  41. EGLintw,h,dummy;
  42. EGLintnumConfigs;
  43. EGLConfigconfig;
  44. EGLSurfacesurface;
  45. EGLContextcontext;
  47. EGLDisplaydisplay=eglGetDisplay(EGL_DEFAULT_DISPLAY);
  49. eglInitialize(display,0,0);
  50. eglChooseConfig(display,attribs,&config,1,&numConfigs);
  51. surface=eglCreateWindowSurface(display,config,s.get(),NULL);
  52. context=eglCreateContext(display,config,NULL,NULL);
  53. eglQuerySurface(display,surface,EGL_WIDTH,&w);
  54. eglQuerySurface(display,surface,EGL_HEIGHT,&h);
  56. if(eglMakeCurrent(display,surface,surface,context)==EGL_FALSE)
  57. returnNO_INIT;
  59. mDisplay=display;
  60. mContext=context;
  61. mSurface=surface;
  62. mWidth=w;
  63. mHeight=h;
  64. mFlingerSurfaceControl=control;
  65. mFlingerSurface=s;
  67. mAndroidAnimation=true;
  69. //Ifthedevicehasencryptionturnedonorisinprocess
  70. //ofbeingencryptedweshowtheencryptedbootanimation.
  71. chardecrypt[PROPERTY_VALUE_MAX];
  72. property_get("vold.decrypt",decrypt,"");
  74. boolencryptedAnimation=atoi(decrypt)!=0||!strcmp("trigger_restart_min_framework",decrypt);
  76. if((encryptedAnimation&&
  77. (access(SYSTEM_ENCRYPTED_BOOTANIMATION_FILE,R_OK)==0)&&
  78. (mZip.open(SYSTEM_ENCRYPTED_BOOTANIMATION_FILE)==NO_ERROR))||
  80. ((access(USER_BOOTANIMATION_FILE,R_OK)==0)&&
  81. (mZip.open(USER_BOOTANIMATION_FILE)==NO_ERROR))||
  83. ((access(SYSTEM_BOOTANIMATION_FILE,R_OK)==0)&&
  84. (mZip.open(SYSTEM_BOOTANIMATION_FILE)==NO_ERROR))){
  85. mAndroidAnimation=false;
  86. }
  88. returnNO_ERROR;
  89. }

threadloop实现 [cpp] view plain copy
  1. boolBootAnimation::threadLoop()
  2. {
  3. boolr;
  4. if(mAndroidAnimation){
  5. r=android();//显示android默认动画
  6. }else{
  7. r=movie();//显示自定义的动画
  8. }
  10. //Noneedtoforceexitanymore
  11. property_set(EXIT_PROP_NAME,"0");
  13. eglMakeCurrent(mDisplay,EGL_NO_SURFACE,EGL_NO_SURFACE,EGL_NO_CONTEXT);
  14. eglDestroyContext(mDisplay,mContext);
  15. eglDestroySurface(mDisplay,mSurface);
  16. mFlingerSurface.clear();
  17. mFlingerSurfaceControl.clear();
  18. eglTerminate(mDisplay);
  19. IPCThreadState::self()->stopProcess();
  20. returnr;
  21. }

movie()的实现 [cpp] view plain copy
  1. boolBootAnimation::movie()
  2. {
  3. //读取bootanimation.zip文件并解释
  5. //clearscreen
  6. //下面是循环显示
  7. for(inti=0;i<pcount;i++){
  8. constAnimation::Part&part(animation.parts[i]);
  9. constsize_tfcount=part.frames.size();
  10. glBindTexture(GL_TEXTURE_2D,0);
  12. for(intr=0;!part.count||r<part.count;r++){
  13. //Exitanynonplayuntilcompletepartsimmediately
  14. if(exitPending()&&!part.playUntilComplete)
  15. break;
  17. for(intj=0;j<fcount&&(!exitPending()||part.playUntilComplete);j++){
  18. constAnimation::Frame&frame(part.frames[j]);
  19. nsecs_tlastFrame=systemTime();
  21. if(r>0){
  22. glBindTexture(GL_TEXTURE_2D,frame.tid);
  23. }else{
  24. if(part.count!=1){
  25. glGenTextures(1,&frame.tid);
  26. glBindTexture(GL_TEXTURE_2D,frame.tid);
  27. glTexParameterx(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
  28. glTexParameterx(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
  29. }
  30. initTexture(
  31. frame.map->getDataPtr(),
  32. frame.map->getDataLength());
  33. }
  35. if(!clearReg.isEmpty()){
  36. Region::const_iteratorhead(clearReg.begin());
  37. Region::const_iteratortail(clearReg.end());
  38. glEnable(GL_SCISSOR_TEST);
  39. while(head!=tail){
  40. constRect&r(*head++);
  41. glScissor(r.left,mHeight-r.bottom,
  42. r.width(),r.height());
  43. glClear(GL_COLOR_BUFFER_BIT);
  44. }
  45. glDisable(GL_SCISSOR_TEST);
  46. }
  47. glDrawTexiOES(xc,yc,0,animation.width,animation.height);
  48. eglSwapBuffers(mDisplay,mSurface);
  50. nsecs_tnow=systemTime();
  51. nsecs_tdelay=frameDuration-(now-lastFrame);
  52. //ALOGD("%lld,%lld",ns2ms(now-lastFrame),ns2ms(delay));
  53. lastFrame=now;
  55. if(delay>0){
  56. structtimespecspec;
  57. spec.tv_sec=(now+delay)/1000000000;
  58. spec.tv_nsec=(now+delay)%1000000000;
  59. interr;
  60. do{
  61. err=clock_nanosleep(CLOCK_MONOTONIC,TIMER_ABSTIME,&spec,NULL);
  62. }while(err<0&&errno==EINTR);
  63. }
  65. checkExit();//检测是否退出动画
  66. }
  68. usleep(part.pause*ns2us(frameDuration));
  70. //Forinfiniteparts,we'venowplayedthematleastonce,soperhapsexit
  71. if(exitPending()&&!part.count)
  72. break;
  73. }
  75. //freethetexturesforthispart
  76. if(part.count!=1){
  77. for(intj=0;j<fcount;j++){
  78. constAnimation::Frame&frame(part.frames[j]);
  79. glDeleteTextures(1,&frame.tid);
  80. }
  81. }
  82. }
  84. returnfalse;
  85. }

那么到movie为止，动画是在播放了，而且还在循环检测是否退出，即checkExit()


checkExit()的实现

[cpp] view plain copy
  1. voidBootAnimation::checkExit(){
  2. //Allowsurfaceflingertogracefullyrequestshutdown
  3. charvalue[PROPERTY_VALUE_MAX];
  4. property_get(EXIT_PROP_NAME,value,"0");//属性为1，说明要退出了
  5. intexitnow=atoi(value);
  6. if(exitnow){
  7. requestExit();
  8. }
  9. }

[cpp] view plain copy
  1. property_get(EXIT_PROP_NAME,value,"0");检测这个属性，=1就退出动画
[cpp] view plain copy
  1. #defineEXIT_PROP_NAME"service.bootanim.exit"
这个属性就是上面讲到的，等到launcher跑起来后就会置1

那动画是什么时候退出的？

当launcher应用程序主线程跑起来后，如果主线程处于空闲，就会向ActivityManagerService发送一个activityIdle的消息。

应用程序主线程是ActivityThread.java来描述的，activityIdle是这个类来实现的

[cpp] view plain copy
  1. privateclassIdlerimplementsMessageQueue.IdleHandler{
  2. ...
  3. IActivityManageram=ActivityManagerNative.getDefault();
  4. ...
  5. try{
  6. am.activityIdle(a.token,a.createdConfig,stopProfiling);
  7. a.createdConfig=null;
  8. }catch(RemoteExceptionex){
  9. //Ignore
  10. }
  11. ....
  12. }

上面的ActivityManagerNavtive.getDefault()得到am

来到frameworks/base/core/java/android/app/ActivityManagerNative.java

[cpp] view plain copy
  1. staticpublicIActivityManagergetDefault(){
  2. returngDefault.get();//getDefault的实现
  3. }

[cpp] view plain copy
  1. privatestaticfinalSingleton<IActivityManager>gDefault=newSingleton<IActivityManager>(){
  2. protectedIActivityManagercreate(){
  3. IBinderb=ServiceManager.getService("activity");
  4. if(false){
  5. Log.v("ActivityManager","defaultservicebinder="+b);
  6. }
  7. IActivityManageram=asInterface(b);
  8. if(false){
  9. Log.v("ActivityManager","defaultservice="+am);
  10. }
  11. returnam;
  12. }
  13. };

gDefault实际上是IActivityManager,往下看

[cpp] view plain copy
  1. classActivityManagerProxyimplementsIActivityManager
  2. {


ActivityManagerProxy实现了IActivityManager

那么am.activityIdle()就是ActivityManagerProxy里的函数，如下

[cpp] view plain copy
  1. publicvoidactivityIdle(IBindertoken,Configurationconfig,booleanstopProfiling)
  2. throwsRemoteException
  3. {
  4. ...
  5. mRemote.transact(ACTIVITY_IDLE_TRANSACTION,data,reply,IBinder.FLAG_ONEWAY);//发送ACTIVITY_IDLE_TRANSACTION
  7. ....
  8. }

发送了ACTIVITY_IDLE_TRANSACTION的进程间通信，这个消息被 ActivityManagerNative接收处理了。

[cpp] view plain copy
  1. caseACTIVITY_IDLE_TRANSACTION:{//收到消息
  2. data.enforceInterface(IActivityManager.descriptor);
  3. IBindertoken=data.readStrongBinder();
  4. Configurationconfig=null;
  5. if(data.readInt()!=0){
  6. config=Configuration.CREATOR.createFromParcel(data);
  7. }
  8. booleanstopProfiling=data.readInt()!=0;
  9. if(token!=null){
  10. activityIdle(token,config,stopProfiling);//这个函数在ActivityManagerService被重写
  11. }
  12. reply.writeNoException();
  13. returntrue;
  14. }

收到消息后就调用了activityIdle函数，这个函数被ActivityManagerService重写了，如下

frameworks/base/services/java/com/android/server/am/ActivityManagerService.java

[cpp] view plain copy
  1. @Override
  2. publicfinalvoidactivityIdle(IBindertoken,Configurationconfig,booleanstopProfiling){
  3. finallongorigId=Binder.clearCallingIdentity();
  4. synchronized(this){
  5. ActivityStackstack=ActivityRecord.getStackLocked(token);
  6. if(stack!=null){
  7. ActivityRecordr=
  8. mStackSupervisor.activityIdleInternalLocked(token,false,config);
  9. if(stopProfiling){
  10. if((mProfileProc==r.app)&&(mProfileFd!=null)){
  11. try{
  12. mProfileFd.close();
  13. }catch(IOExceptione){
  14. }
  15. clearProfilerLocked();
  16. }
  17. }
  18. }
  19. }
  20. Binder.restoreCallingIdentity(origId);
  21. }

调用activityIdleInternalLocked函数，在下面实现

frameworks/base/services/java/com/android/server/am/ActivityStackSupervisor.java

[cpp] view plain copy
  1. finalActivityRecordactivityIdleInternalLocked(finalIBindertoken,booleanfromTimeout,
  2. Configurationconfig){
  3. ....
  5. if(enableScreen){
  6. mService.enableScreenAfterBoot();//调ActivityManagerService类的enableScreenAfterBoot()函数
  7. }
  8. ....
  9. if(activityRemoved){
  10. resumeTopActivitiesLocked();
  11. }
  13. returnr;
  14. }


来到frameworks/base/services/java/com/android/server/am/ActivityManagerService.java

[cpp] view plain copy
  1. voidenableScreenAfterBoot(){
  2. EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_ENABLE_SCREEN,
  3. SystemClock.uptimeMillis());
  4. mWindowManager.enableScreenAfterBoot();//调WindowManagerService类里的enableScreenAfterBoot()函数
  6. synchronized(this){
  7. updateEventDispatchingLocked();
  8. }
  9. }

来到frameworks/base/services/java/com/android/server/wm/WindowManagerService.java


[cpp] view plain copy
  1. publicvoidenableScreenAfterBoot(){
  2. ....
  4. performEnableScreen();
  5. }

performEnableScreen()实现


[cpp] view plain copy
  1. publicvoidperformEnableScreen(){
  4. ..
  5. surfaceFlinger.transact(IBinder.FIRST_CALL_TRANSACTION,//BOOT_FINISHED
  6. data,null,0);
  7. ....
  8. }

发送了FIRST_CALL_TRANSACTION的请求



因为从下面知道FIRST_CALL_TRANSACTION = BOOT_FINISHED

所以BnSurfaceComposer收到消息

frameworks/native/include/gui/ISurfaceComposer.h

[cpp] view plain copy
  1. classBnSurfaceComposer:publicBnInterface<ISurfaceComposer>{
  2. public:
  3. enum{
  4. //Note:BOOT_FINISHEDmustremainthisvalue,itiscalledfrom
  5. //JavabyActivityManagerService.
  6. BOOT_FINISHED=IBinder::FIRST_CALL_TRANSACTION,
  7. ...
  8. };
  10. virtualstatus_tonTransact(uint32_tcode,constParcel&data,
  11. Parcel*reply,uint32_tflags=0);
  12. };


[cpp] view plain copy
  1. </pre></p><p><spanstyle="color:#333333;">frameworks/native/libs/gui/ISurfaceComposer.cpp</span></p><p><spanstyle="color:#333333;"></span><prename="code"class="cpp">status_tBnSurfaceComposer::onTransact(
  2. uint32_tcode,constParcel&data,Parcel*reply,uint32_tflags)
  3. {
  4. switch(code){
  6. ....
  7. caseBOOT_FINISHED:{
  8. CHECK_INTERFACE(ISurfaceComposer,data,reply);
  9. bootFinished();//调用bootFinished()
  10. returnNO_ERROR;
  11. }
  13. ....
  14. }
  15. //shouldbeunreachable
  16. returnNO_ERROR;
  17. }

bootFinished()函数BpSurfaceComposer里实现，但发现没有，他又发了一个BOOT_FINISHED，死循环了，其实没有。bootFinished()被 SurfaceFlinger类重写了

[cpp] view plain copy
  1. classBpSurfaceComposer:publicBpInterface<ISurfaceComposer>
  2. {
  4. virtualvoidbootFinished()
  5. {
  6. Parceldata,reply;
  7. data.writeInterfaceToken(ISurfaceComposer::getInterfaceDescriptor());
  8. remote()->transact(BnSurfaceComposer::BOOT_FINISHED,data,&reply);
  9. }

重写

frameworks/native/services/surfaceflinger/SurfaceFlinger.cpp

[cpp] view plain copy
  1. voidSurfaceFlinger::bootFinished()
  2. {
  3. ...
  4. property_set("service.bootanim.exit","1");
  5. }

把service.bootanim.exit写成1，然后bootanimation进程的checkExit()检测到就退出进程，停止播放。

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