android开机动画启动流程
从知道，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。
service surfaceflinger /system/bin/surfaceflinger class main user system group graphics drmrpc onrestart restart zygotesurfaceflinger进程便启动了，跟着就会跑进程的main()函数。
frameworks/native/services/surfaceflinger/main_surfaceflinger.cpp
int main(int argc, char** argv) {.... // instantiate surfaceflinger sp flinger = new SurfaceFlinger();//创建surfaceflinger服务实例.... flinger->init(); // publish surface flinger sp sm(defaultServiceManager()); sm->addService(String16(SurfaceFlinger::getServiceName()), flinger, false);//注册到service manager里 // run in this thread flinger->run();//开跑 return 0;} 首先new一个SurfaceFlinger实例，然后init，然后run
frameworks/native/services/surfaceflinger/SurfaceFlinger.cpp
void SurfaceFlinger::init() { ALOGI( "SurfaceFlinger's main thread ready to run. " "Initializing graphics H/W..."); ..... // start boot animation startBootAnim();//开始播放动画} 初始化graphics之后，就调用startBootAnim()播放开机动画。
void SurfaceFlinger::startBootAnim() { // start boot animation mBootFinished = false; property_set("service.bootanim.exit", "0");//这个会有bootanimation进程周期检测,=1退出动画 property_set("ctl.start", "bootanim");//通过ctl.start命令启动bootanim} 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
int main(int argc, char** argv){ sp proc(ProcessState::self()); ProcessState::self()->startThreadPool(); // create the boot animation object sp boot = new BootAnimation();//创建BootAnimation实例 IPCThreadState::self()->joinThreadPool();//binder线程池，与surfaceflinger通信用的。 } return 0;} 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
BootAnimation::BootAnimation() : Thread(false){ mSession = new SurfaceComposerClient();//创建一个对象} 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 void BootAnimation::onFirstRef() { status_t err = mSession->linkToComposerDeath(this);//注册surfaceflinger死亡消息的通知书 ALOGE_IF(err, "linkToComposerDeath failed (%s) ", strerror(-err)); if (err == NO_ERROR) { run("BootAnimation", PRIORITY_DISPLAY);//开跑 }} 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。
void BootAnimation::binderDied(const wp& who){ // woah, surfaceflinger died! ALOGD("SurfaceFlinger died, exiting..."); // calling requestExit() is not enough here because the Surface code // might be blocked on a condition variable that will never be updated. kill( getpid(), SIGKILL );//收到surfaceflinger死亡的消息，好吧自己也跟着去了。 requestExit();}
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
status_t Thread::run(const char* name, int32_t priority, size_t stack){ ... if (mCanCallJava) { res = createThreadEtc(_threadLoop,//创建线程 this, name, priority, stack, &mThread); } else { res = androidCreateRawThreadEtc(_threadLoop, this, name, priority, stack, &mThread); } ....} 创建_threadLoop线程
int Thread::_threadLoop(void* user){.... do { bool result; if (first) { first = false; self->mStatus = self->readyToRun();//这个函数被bootanimation重写了 result = (self->mStatus == NO_ERROR); if (result && !self->exitPending()) { ... result = self->threadLoop();//这个函数被bootanimation重写了 } } else { result = self->threadLoop(); } ... return 0;}
readyToRun函数实现
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; char value[PROPERTY_VALUE_MAX]; property_get("persist.panel.orientation", value, "0"); int orient = atoi(value) / 90; if(orient == eOrientation90 || orient == eOrientation270) { int temp = dinfo.h; dinfo.h = dinfo.w; dinfo.w = temp; } Rect destRect(dinfo.w, dinfo.h); mSession->setDisplayProjection(dtoken, orient, destRect, destRect); // 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, 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); if ((encryptedAnimation && (access(SYSTEM_ENCRYPTED_BOOTANIMATION_FILE, R_OK) == 0) && (mZip.open(SYSTEM_ENCRYPTED_BOOTANIMATION_FILE) == NO_ERROR)) || ((access(USER_BOOTANIMATION_FILE, R_OK) == 0) && (mZip.open(USER_BOOTANIMATION_FILE) == NO_ERROR)) || ((access(SYSTEM_BOOTANIMATION_FILE, R_OK) == 0) && (mZip.open(SYSTEM_BOOTANIMATION_FILE) == NO_ERROR))) { mAndroidAnimation = false; } return NO_ERROR;} threadloop实现
bool BootAnimation::threadLoop(){ bool r; if (mAndroidAnimation) { r = android();//显示android默认动画 } else { r = movie();//显示自定义的动画 } // No need to force exit anymore property_set(EXIT_PROP_NAME, "0"); 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;} movie()的实现
bool BootAnimation::movie(){ //读取bootanimation.zip文件并解释 // clear screen //下面是循环显示 for (int i=0 ; i 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();//检测是否退出动画 } 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
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
void BootAnimation::checkExit() { // Allow surface flinger to gracefully request shutdown char value[PROPERTY_VALUE_MAX]; property_get(EXIT_PROP_NAME, value, "0");//属性为1，说明要退出了 int exitnow = atoi(value); if (exitnow) { requestExit(); }}
property_get(EXIT_PROP_NAME, value, "0");检测这个属性，=1就退出动画
#define EXIT_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
private class Idler implements MessageQueue.IdleHandler {... IActivityManager am = ActivityManagerNative.getDefault(); ... try { am.activityIdle(a.token, a.createdConfig, stopProfiling); a.createdConfig = null; } catch (RemoteException ex) { // Ignore } .... } 上面的ActivityManagerNavtive.getDefault()得到am
来到frameworks/base/core/java/android/app/ActivityManagerNative.java
static public IActivityManager getDefault() { return gDefault.get();//getDefault的实现 }private static final Singleton gDefault = new Singleton () { protected IActivityManager create() { IBinder b = ServiceManager.getService("activity"); if (false) { Log.v("ActivityManager", "default service binder = " + b); } IActivityManager am = asInterface(b); if (false) { Log.v("ActivityManager", "default service = " + am); } return am; } };
gDefault实际上是IActivityManager,往下看
class ActivityManagerProxy implements IActivityManager{ ActivityManagerProxy实现了IActivityManager
那么am.activityIdle()就是ActivityManagerProxy里的函数，如下
public void activityIdle(IBinder token, Configuration config, boolean stopProfiling) throws RemoteException { ... mRemote.transact(ACTIVITY_IDLE_TRANSACTION, data, reply, IBinder.FLAG_ONEWAY);//发送ACTIVITY_IDLE_TRANSACTION .... } 发送了ACTIVITY_IDLE_TRANSACTION的进程间通信，这个消息被 ActivityManagerNative接收处理了。
case ACTIVITY_IDLE_TRANSACTION: { //收到消息 data.enforceInterface(IActivityManager.descriptor); IBinder token = data.readStrongBinder(); Configuration config = null; if (data.readInt() != 0) { config = Configuration.CREATOR.createFromParcel(data); } boolean stopProfiling = data.readInt() != 0; if (token != null) { activityIdle(token, config, stopProfiling);//这个函数在ActivityManagerService被重写 } reply.writeNoException(); return true; } 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
@Override public final void activityIdle(IBinder token, Configuration config, boolean stopProfiling) { final long origId = Binder.clearCallingIdentity(); synchronized (this) { ActivityStack stack = ActivityRecord.getStackLocked(token); if (stack != null) { ActivityRecord r = mStackSupervisor.activityIdleInternalLocked(token, false, config); if (stopProfiling) { if ((mProfileProc == r.app) && (mProfileFd != null)) { try { mProfileFd.close(); } catch (IOException e) { } clearProfilerLocked(); } } } } Binder.restoreCallingIdentity(origId); } 调用activityIdleInternalLocked函数，在下面实现
frameworks/base/services/java/com/android/server/am/ActivityStackSupervisor.java
final ActivityRecord activityIdleInternalLocked(final IBinder token, boolean fromTimeout, Configuration config) { .... if (enableScreen) { mService.enableScreenAfterBoot();//调ActivityManagerService类的enableScreenAfterBoot()函数 }.... if (activityRemoved) { resumeTopActivitiesLocked(); } return r; }
来到frameworks/base/services/java/com/android/server/am/ActivityManagerService.java
void enableScreenAfterBoot() { EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_ENABLE_SCREEN, SystemClock.uptimeMillis()); mWindowManager.enableScreenAfterBoot();//调WindowManagerService类里的enableScreenAfterBoot()函数 synchronized (this) { updateEventDispatchingLocked(); } }
来到frameworks/base/services/java/com/android/server/wm/WindowManagerService.java
public void enableScreenAfterBoot() { .... performEnableScreen(); } performEnableScreen()实现
public void performEnableScreen() { ..... surfaceFlinger.transact(IBinder.FIRST_CALL_TRANSACTION, // BOOT_FINISHED data, null, 0); .... } 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
class BnSurfaceComposer: public BnInterface{public: enum { // Note: BOOT_FINISHED must remain this value, it is called from // Java by ActivityManagerService. BOOT_FINISHED = IBinder::FIRST_CALL_TRANSACTION, ... }; virtual status_t onTransact(uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags = 0);}; frameworks/native/libs/gui/ISurfaceComposer.cpp
status_t BnSurfaceComposer::onTransact( uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags){ switch(code) { .... case BOOT_FINISHED: { CHECK_INTERFACE(ISurfaceComposer, data, reply); bootFinished();//调用 bootFinished() return NO_ERROR; } .... } // should be unreachable return NO_ERROR;}
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
class BpSurfaceComposer : public BpInterface{ virtual void bootFinished() { Parcel data, reply; data.writeInterfaceToken(ISurfaceComposer::getInterfaceDescriptor()); remote()->transact(BnSurfaceComposer::BOOT_FINISHED, data, &reply); }
重写
frameworks/native/services/surfaceflinger/SurfaceFlinger.cpp
void SurfaceFlinger::bootFinished(){... property_set("service.bootanim.exit", "1");} 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。