[Android5.1]开机动画显示工作流程分析
网上有很多关于android开机动画显示的分析，但大部分是针对于android的早期版本。在android5.1中，开机动画显示的工作流程做了一些修改，下面就针对android5.1，分析一下开机动画的启动、显示和停止的整个过程。
1. bootanimation应用的启动过程
Android系统开机动画的显示是由bootanimation应用实现的。
bootanimation在init.rc中的定义如下：
service bootanim /system/bin/bootanimation
class core
user graphics
group graphics audio
disabled
oneshot可见，由于设置为"disable"，该应用在init启动过程中是不会启动的，需要其他地方显示的调用才能启动。那是什么时候启动的呢？当SurfaceFlinger服务启动时，会修改系统属性值ctl.start，通知init进程启动bootanimation。
在早期的Android版本中，SurfaceFlinger服务是由SystemServer启动的。但在Android5.1中，该服务是init进程启动过程中就启动了。在init.rc中能看到对该服务的描述：
service surfaceflinger /system/bin/surfaceflinger
class core
user system
group graphics drmrpc
onrestart restart zygoteSurfaceFlinger服务源码路径为：frameworks\native\services\surfaceflinger
服务的入口在main_surfaceflinger.cpp中，具体为：
int main(int, char**) {
// When SF is launched in its own process, limit the number of
// binder threads to 4.
ProcessState::self()->setThreadPoolMaxThreadCount(4);
// start the thread pool
sp ps(ProcessState::self());
ps->startThreadPool();
// instantiate surfaceflinger
sp flinger = new SurfaceFlinger();
#if defined(HAVE_PTHREADS)
setpriority(PRIO_PROCESS, 0, PRIORITY_URGENT_DISPLAY);
#endif
set_sched_policy(0, SP_FOREGROUND);
// initialize before clients can connect
flinger->init();
// publish surface flinger
sp sm(defaultServiceManager());
sm->addService(String16(SurfaceFlinger::getServiceName()), flinger, false);
// run in this thread
flinger->run();
return 0;
}
下面主要看一下SurfaceFlinger::init()方法，具体代码为：
void SurfaceFlinger::init() {
ALOGI( "SurfaceFlinger's main thread ready to run. "
"Initializing graphics H/W...");
......
// start boot animation
startBootAnim();
}void SurfaceFlinger::startBootAnim() {
// start boot animation
property_set("service.bootanim.exit", "0");
property_set("ctl.start", "bootanim");
}
可见，将系统属性ctl.start的值设置为"bootanim"。
回到init进程的init.c的main函数中：
int main(int argc, char **argv) {
.......
for(;;) {
.......
nr = poll(ufds, fd_count, timeout);
if (nr <= 0)
continue;
for (i = 0; i < fd_count; i++) {
if (ufds[i].revents & POLLIN) {
if (ufds[i].fd == get_property_set_fd())
handle_property_set_fd();
else if (ufds[i].fd == get_keychord_fd())
handle_keychord();
else if (ufds[i].fd == get_signal_fd())
handle_signal();
}
}
}
}if(memcmp(msg.name,"ctl.",4) == 0) {
// Keep the old close-socket-early behavior when handling
// ctl.* properties.
close(s);
if (check_control_mac_perms(msg.value, source_ctx)) {
handle_control_message((char*) msg.name + 4, (char*) msg.value);
} else {
ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
}
} 该函数会进一步执行handle_control_message()，传入的参数msg.name=ctl.start，msg.value=bootanim。
void handle_control_message(const char *msg, const char *arg)
{
if (!strcmp(msg,"start")) {
msg_start(arg);
} else if (!strcmp(msg,"stop")) {
msg_stop(arg);
} else if (!strcmp(msg,"restart")) {
msg_restart(arg);
} else {
ERROR("unknown control msg '%s'\n", msg);
}
}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);
}到此，bootanimation应用就启动了。
2. 开机动画的显示过程
下面，开始分析bootanimation是如何绘制并在屏幕上显示开机动画的。
代码路径为：frameworks\base\cmds\bootanimation。包括以下几个文件：
Android.mk ----------- 编译文件
BootAnimation.cpp ----------- BootAnimation类的定义和实现
BootAnimation.h ----------- BootAnimation的声明
BootAnimation_main.cpp ----------- 程序入口
AudioPlayer.cpp ----------- 视频播放类的定义和实现
AudioPlayer.h ----------- 视频播放类的声明
先看一下bootanimation的入口，BootAnimation_main.cpp中的main函数：
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) {
sp proc(ProcessState::self());
ProcessState::self()->startThreadPool();
sp boota = new BootAnimation();
IPCThreadState::self()->joinThreadPool();
}
return 0;
}
Main函数首先获取属性"debug.sf.nobootanimation"的值并判断，如果为1，函数退出，开机动画就不会显示了。如果为0，会开启一个binder线程池，用来在开机动画的过程中，与SurfaceFlinger通信，接着创建一个BootAnimation对象，该对象就是用来显示开机动画的。下面看一下BootAnimation类的声明：
class BootAnimation : public Thread, public IBinder::DeathRecipient
{
public:
BootAnimation();
virtual ~BootAnimation();
.......
private:
virtual bool threadLoop();
virtual status_t readyToRun();
virtual void onFirstRef();
virtual void binderDied(const wp& who);
status_t initTexture(Texture* texture, AssetManager& asset, const char* name);
status_t initTexture(const Animation::Frame& frame);
bool android();
bool readFile(const char* name, String8& outString);
bool movie();
......
}; onFirstRef() ----- 属于其父类RefBase，该函数在强引用sp新增引用计数時调用，就是当有sp包装的类初始化的时候调用；
binderDied() ----- 当对象死掉或者其他情况导致该Binder结束时，就会回调binderDied()方法;
readyToRun() ----- Thread执行前的初始化工作；
threadLoop() ----- 每个线程类都要实现的，在这里定义thread的执行内容。这个函数如果返回true，且没有requestExist()没有被调用，则该函数会再次执行；如果返回false，则threadloop中的内容仅仅执行一次，线程就会退出。
其他主要函数的说明如下：
android() ----- 显示系统默认的开机画面；
movie() ----- 显示用户自定义的开机动画。
BootAnimationL类的构造函数：
BootAnimation::BootAnimation() : Thread(false), mZip(NULL),mfd(-1)
{
mSession = new SurfaceComposerClient();
}主要是new一个SurfaceComposerClient对象，用来和SurfaceFlinger进行binder进程间通信。
由于在BootAnimation_main.cpp的main函数创建BootAnimation对象时，使用了智能指针引用，因此还会调用onFirstRef()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);
}
}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;
sp control = session()->createSurface(String8("BootAnimation"),
dinfo.w, dinfo.h, PIXEL_FORMAT_RGB_565);
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;
// 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);
ZipFileRO* zipFile = NULL;
if ((encryptedAnimation &&
(access(SYSTEM_ENCRYPTED_BOOTANIMATION_FILE, R_OK) == 0) &&
((zipFile = ZipFileRO::open(SYSTEM_ENCRYPTED_BOOTANIMATION_FILE)) != NULL)) ||
((access(OEM_BOOTANIMATION_FILE, R_OK) == 0) &&
((zipFile = ZipFileRO::open(OEM_BOOTANIMATION_FILE)) != NULL)) ||
((access(SYSTEM_BOOTANIMATION_FILE, R_OK) == 0) &&
((zipFile = ZipFileRO::open(SYSTEM_BOOTANIMATION_FILE)) != NULL))) {
mZip = zipFile;
}
return NO_ERROR;
} readyToRun函数主要做了一下几个工作：
第一，调用SurfaceComposerClient对象mSession的成员函数createSurface，获得一个SurfaceControl对象control，然后调用control的成员函数getSurface，获得一个Surface对象s。control和s都可以与SurgaceFlinger通过binder进行通信。
第二，初始化IOPENEGL和EGL。主要是四个参数：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。
第三，读取动画文件。动画文件的读取是按顺序进行的，如果读取成功，则不再读取后续的文件，如果失败，则读取下一个文件。顺序如下：
1--如果设备的加密功能已经开启，或者设备正在进行加密，则读取加密开机动画文件，路径为
#define SYSTEM_ENCRYPTED_BOOTANIMATION_FILE "/system/media/bootanimation-encrypted.zip"2--OEM厂商指定的开机动画，路径为：
#define OEM_BOOTANIMATION_FILE "/oem/media/bootanimation.zip"
#define SYSTEM_BOOTANIMATION_FILE "/system/media/bootanimation.zip"线程的初始化工作完成后，就要进入线程的主体函数，完成开机动画的绘制和显示。具体函数为threadLoop()：
bool BootAnimation::threadLoop()
{
bool r;
// We have no bootanimation file, so we use the stock android logo
// animation.
if (mZip == NULL) {
r = android();
} else {
r = movie();
}
eglMakeCurrent(mDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
eglDestroyContext(mDisplay, mSurface);
mFlingerSurface.clear();
mFlingerSurfaceControl.clear();
eglTerminate(mDisplay);
IPCThreadState::self()->stopProcess();
return r;
}这个函数流程比较简单，首先判断自定义的开机动画文件mZip是否存在，如果存在就调用movie()完成自定义开机画面的显示；如果不存在，调用android()完成系统默认开机画面的显示。然后进行开机动画显示后的销毁、释放工作，主要就是readyToRun中初始化的一些EGL对象。最后终止线程，并return。注意，movie()和android()的返回值都是false，因此线程结束也会返回false。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。
android()代码如下：
bool BootAnimation::android()
{
initTexture(&mAndroid[0], mAssets, "images/android-logo-mask.png");
initTexture(&mAndroid[1], mAssets, "images/android-logo-shine.png");
// clear screen
glShadeModel(GL_FLAT);
glDisable(GL_DITHER);
glDisable(GL_SCISSOR_TEST);
glClearColor(0,0,0,1);
glClear(GL_COLOR_BUFFER_BIT);
eglSwapBuffers(mDisplay, mSurface);
glEnable(GL_TEXTURE_2D);
glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
const GLint xc = (mWidth - mAndroid[0].w) / 2;
const GLint yc = (mHeight - mAndroid[0].h) / 2;
const Rect updateRect(xc, yc, xc + mAndroid[0].w, yc + mAndroid[0].h);
glScissor(updateRect.left, mHeight - updateRect.bottom, updateRect.width(),
updateRect.height());
// Blend state
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
const nsecs_t startTime = systemTime();
do {
nsecs_t now = systemTime();
double time = now - startTime;
float t = 4.0f * float(time / us2ns(16667)) / mAndroid[1].w;
GLint offset = (1 - (t - floorf(t))) * mAndroid[1].w;
GLint x = xc - offset;
glDisable(GL_SCISSOR_TEST);
glClear(GL_COLOR_BUFFER_BIT);
glEnable(GL_SCISSOR_TEST);
glDisable(GL_BLEND);
glBindTexture(GL_TEXTURE_2D, mAndroid[1].name);
glDrawTexiOES(x, yc, 0, mAndroid[1].w, mAndroid[1].h);
glDrawTexiOES(x + mAndroid[1].w, yc, 0, mAndroid[1].w, mAndroid[1].h);
glEnable(GL_BLEND);
glBindTexture(GL_TEXTURE_2D, mAndroid[0].name);
glDrawTexiOES(xc, yc, 0, mAndroid[0].w, mAndroid[0].h);
EGLBoolean res = eglSwapBuffers(mDisplay, mSurface);
if (res == EGL_FALSE)
break;
// 12fps: don't animate too fast to preserve CPU
const nsecs_t sleepTime = 83333 - ns2us(systemTime() - now);
if (sleepTime > 0)
usleep(sleepTime);
checkExit();
} while (!exitPending());
glDeleteTextures(1, &mAndroid[0].name);
glDeleteTextures(1, &mAndroid[1].name);
return false;
}首先，调用initTexture读取android系统默认的开机动画图片，生成纹理对象，并放在mAndroid数组中。开机动画图片共两张：android-logo-mask.png和android-logo-shine.png，存放在frameworks\base\core\res\assets\images路径下。其中android-logo-mask.png是黑底白字“android”字样；android-logo-shine.png是黑白渐变的显示背景。接着，clear screen。然后，在do...while循环中渲染两个纹理对象，从而生成开机动画。在循环语句最后会执行checkExit()函数。
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();
if (mAudioPlayer != NULL) {
mAudioPlayer->requestExit();
}
}
}首先调用property_get获取属性EXIT_PROP_NAME的值。
#define EXIT_PROP_NAME "service.bootanim.exit"然后判断该值，如果为1，则调用requestExit（）要求退出当前线程，该函数是异步的。
回到android()代码：
while (!exitPending());这样，当属性“service.bootanim.exit”值被设为"1"时，android()就会调用requestExit()，exitPending()返回值为true。于是do...while()循环就会退出，开机动画绘制就会结束。
至于什么时候是哪个服务将属性“service.bootanim.exit”的值设置为1的，我们后面讲开机动画的停止的时候会提到。
下面分析一下movie()函数的具体实现。由于函数比较长，所以这里分段分析。
String8 desString;
if (!readFile("desc.txt", desString)) {
return false;
}
char const* s = desString.string();
// Create and initialize an AudioPlayer if we have an audio_conf.txt file
String8 audioConf;
if (readFile("audio_conf.txt", audioConf)) {
mAudioPlayer = new AudioPlayer;
if (!mAudioPlayer->init(audioConf.string())) {
ALOGE("mAudioPlayer.init failed");
mAudioPlayer = NULL;
}
}480 800 30
p 1 0 folder0
p 0 10 folder1第一行：前两个是开机动画在屏幕上显示的像素大小，分别为宽度和高度。第三个数字为每秒显示的帧数。
下面两行描述开机动画文件及显示的次数和间隔时间，每一行为一个片段。第一项类型，如p或c；第二项为该动画文件显示的次数，“0”表示重复显示；第三项为两次显示的间隔时间；第四项为动画文件。比如，"p 1 0 folder0"表示folder0文件夹中的动画只显示一次；”p 0 10 folder1“表示folder1中的动画文件重复显示，且两次显示的间隔时间为10秒。
// Parse the description file
for (;;) {
const char* endl = strstr(s, "\n");
if (!endl) break;
String8 line(s, endl - s);
const char* l = line.string();
int fps, width, height, count, pause;
char path[ANIM_ENTRY_NAME_MAX];
char color[7] = "000000"; // default to black if unspecified
char pathType;
if (sscanf(l, "%d %d %d %d", &width, &height, &fps, &flg) >= 3) {
//ALOGD("> w=%d, h=%d, fps=%d, flg=%d", width, height, fps, flg);
animation.width = width;
animation.height = height;
animation.fps = fps;
}
else if (sscanf(l, " %c %d %d %s #%6s", &pathType, &count, &pause, path, color) >= 4) {
// ALOGD("> type=%c, count=%d, pause=%d, path=%s, color=%s", pathType, count, pause, path, color);
Animation::Part part;
part.playUntilComplete = pathType == 'c';
part.count = count;
part.pause = pause;
part.path = path;
part.audioFile = NULL;
if (!parseColor(color, part.backgroundColor)) {
ALOGE("> invalid color '#%s'", color);
part.backgroundColor[0] = 0.0f;
part.backgroundColor[1] = 0.0f;
part.backgroundColor[2] = 0.0f;
}
animation.parts.add(part);
}
s = ++endl;
}上面这段代码主要是解析上面读取的desc.txt，并将相关参数保存到Animation对象animation中。
// read all the data structures
const size_t pcount = animation.parts.size();
void *cookie = NULL;
if (!mZip->startIteration(&cookie)) {
return false;
}
ZipEntryRO entry;
char name[ANIM_ENTRY_NAME_MAX];
while ((entry = mZip->nextEntry(cookie)) != NULL) {
const int foundEntryName = mZip->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) {
for (size_t j=0 ; jgetEntryInfo(entry, &method, NULL, NULL, NULL, NULL, NULL)) {
if (method == ZipFileRO::kCompressStored) {
FileMap* map = mZip->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.audioFile = map;
} else {
Animation::Frame frame;
frame.name = leaf;
frame.map = map;
part.frames.add(frame);
}
}
}
}
}
}
}
}
mZip->endIteration(cookie); 上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。下面就开始将开机动画绘制到屏幕上，代码如下：
// clear screen
glShadeModel(GL_FLAT);
glDisable(GL_DITHER);
glDisable(GL_SCISSOR_TEST);
glDisable(GL_BLEND);
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 (size_t i=0 ; iplayFile(part.audioFile);
}
for (size_t j=0 ; j 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);
}
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 (size_t j=0 ; j 到此，开机动画的显示流程就完成了。下面，分析一下开机动画是怎么停止的。
3 开机动画的停止
当SystemServer将系统中的关键服务启动完成后，会启动桌面启动器Launcher。Launcher启动后，会向ActivityManagerService发送一个Activity组件空闲通知，AMS收到该通知后，就会调用成员函数enableScreenAfterBoot()停止开机动画，以便让屏幕显示桌面。enableScreenAfterBoot()代码如下：
void enableScreenAfterBoot() {
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_ENABLE_SCREEN,
SystemClock.uptimeMillis());
mWindowManager.enableScreenAfterBoot();
synchronized (this) {
updateEventDispatchingLocked();
}
}
public void enableScreenAfterBoot() {
synchronized(mWindowMap) {
......
if (mSystemBooted) {
return;
}
mSystemBooted = true;
hideBootMessagesLocked();
// If the screen still doesn't come up after 30 seconds, give
// up and turn it on.
mH.sendEmptyMessageDelayed(H.BOOT_TIMEOUT, 30*1000);
}
mPolicy.systemBooted();
performEnableScreen();
}成员变量mSystemBooted用来标识系统是否已经启动，true代表启动，false代表未启动。这里，应该是false。因此，程序会继续往下执行，先把mSystemBooted设为true，然后调用performEnableScreen。代码如下：
public void performEnableScreen() {
synchronized(mWindowMap) {
......
if (mDisplayEnabled) {
return;
}
if (!mSystemBooted && !mShowingBootMessages) {
return;
}
// Don't enable the screen until all existing windows have been drawn.
if (!mForceDisplayEnabled && checkWaitingForWindowsLocked()) {
return;
}
if (!mBootAnimationStopped) {
// Do this one time.
try {
IBinder surfaceFlinger = ServiceManager.getService("SurfaceFlinger");
if (surfaceFlinger != null) {
//Slog.i(TAG, "******* TELLING SURFACE FLINGER WE ARE BOOTED!");
Parcel data = Parcel.obtain();
data.writeInterfaceToken("android.ui.ISurfaceComposer");
surfaceFlinger.transact(IBinder.FIRST_CALL_TRANSACTION, // BOOT_FINISHED
data, null, 0);
data.recycle();
}
} catch (RemoteException ex) {
Slog.e(TAG, "Boot completed: SurfaceFlinger is dead!");
}
mBootAnimationStopped = true;
}
......
}SurfaceFlinger中处理该请求的函数为bootFinished。代码如下：
void SurfaceFlinger::bootFinished()
{
const nsecs_t now = systemTime();
const nsecs_t duration = now - mBootTime;
ALOGI("Boot is finished (%ld ms)", long(ns2ms(duration)) );
mBootFinished = true;
// wait patiently for the window manager death
const String16 name("window");
sp window(defaultServiceManager()->getService(name));
if (window != 0) {
window->linkToDeath(static_cast(this));
}
// 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");
} 这里注意：在android之前版本中，bootFinished不是设置属性“service.bootanim.exit”，而是调用：
property_set("ctl.stop", "bootanim");这样，init进程会直接kill掉bootanimation进程，从而结束开机动画的显示。
4 开机音乐的实现
使用MediaPlay实现，思路大致如下：
Makefile文件中添加：
LOCAL_SHARED_LIBRARIES += \
libmedia
#include
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();
}