void SurfaceFlinger::onFirstRef()
{
mEventQueue.init(this);
}
void MessageQueue::init(const sp<surfaceflinger>& flinger)
{
mFlinger = flinger;
mLooper = new Looper(true);
mHandler = new Handler(*this);
}
此处MessageQueue不是常见的消息队列，在surfaceFlinger目录单独编写，mEventQueue更像是消息循环机制的管理者，其中包含了一个looper，一个handler。
/* MessageQueue.cpp */
void MessageQueue::waitMessage() {
int32_tret = mLooper->pollOnce(-1);
}
handler也不是常见的那个handler，而是Messagequeue中自定义的一个事件处理器，是专门为surfaceflinger设计的，handler收到消息，进一步回调surfaceflinger中的onMessageReceived。
void MessageQueue::Handler::handleMessage(constMessage& message) {
switch(message.what) {
caseINVALIDATE:
mQueue.mFlinger->onMessageReceived(message.what);
} }
void SurfaceFlinger::init() {
ALOGI( "SurfaceFlinger's main thread ready to run. "
"Initializing graphics H/W..."); //开始SF线程的准备工作，初始化graphics H/W
{ // Autolock scope
Mutex::Autolock _l(mStateLock);
// initialize EGL for the default display即初始化EGL，作为默认显示（EGL见https://blog.csdn.net/ieearth/article/details/71180457）
mEGLDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);
eglInitialize(mEGLDisplay, NULL, NULL);
// start the EventThread开启事件线程
sp<VSyncSource> vsyncSrc = new DispSyncSource(&mPrimaryDispSync,
vsyncPhaseOffsetNs, true, "app");
mEventThread = new EventThread(vsyncSrc, *this);
sp<VSyncSource> sfVsyncSrc = new DispSyncSource(&mPrimaryDispSync,
sfVsyncPhaseOffsetNs, true, "sf");
mSFEventThread = new EventThread(sfVsyncSrc, *this);
mEventQueue.setEventThread(mSFEventThread);
// set SFEventThread to SCHED_FIFO to minimize jitter
struct sched_param param = {0};
param.sched_priority = 2;
if (sched_setscheduler(mSFEventThread->getTid(), SCHED_FIFO, ¶m) != 0) {
ALOGE("Couldn't set SCHED_FIFO for SFEventThread");
}
// Get a RenderEngine for the given display / config (can't fail)
mRenderEngine = RenderEngine::create(mEGLDisplay,
HAL_PIXEL_FORMAT_RGBA_8888);
}
// Drop the state lock while we initialize the hardware composer. We drop
// the lock because on creation, it will call back into SurfaceFlinger to
// initialize the primary display.即初始化硬件composer对象，和显示设备交互，硬件显示设备
mHwc = new HWComposer(this);
mHwc->setEventHandler(static_cast<HWComposer::EventHandler*>(this));
Mutex::Autolock _l(mStateLock);
// retrieve the EGL context that was selected/created即检索创建的EG