Surfaceflinger process流程分析

 

Surfaceflinger process流程分析

转载地址：http://blog.csdn.net/myarrow/article/details/7165701，多谢分享喽

根据前面的介绍，surfaceflinger作为一个server process（其进程入口见main_surfaceflinger.cpp中的main函数），上层的应用程序（作为client）通过Binder方式与其进行通信。Surfaceflinger作为一个进程，这里把它分为3个部分，如下：

1、 Thread本身处理部分，包括初始化以及thread loop。

2、 Binder部分，负责接收上层应用的各个设置和命令，并反馈状态标志给上层。

3、 与底层的交互，负责调用底层接口（HAL）。

结构图如下：

注释：

a、 Binder接收到应用程序的命令（如创建surface、设置参数等），传递给flinger。

b、 Flinger完成对应命令后将相关结果状态反馈给上层。

c、 在处理上层命令过程中，根据需要设置event（主要和显示有关），通知Thread Loop进行处理。

d、 Flinger根据上层命令通知底层进行处理（主要是设置一些参数，Layer、position等）

e、 Thread Loop中进行surface的合成并通知底层进行显示（Post buffer）。

f、  DisplayHardware层根据flinger命令调用HAL进行HW的操作。

下面来具体分析一些SurfaceFlinger中重要的处理函数以及surface、Layer的属性

1. SurfaceFlinger::readyToRun

   SurfaceFlinger thread的初始化函数，主要任务是分配内存和设置底层接口(EGL&HAL)。

 status_t SurfaceFlinger::readyToRun()
 {
     LOGI(   "SurfaceFlinger's main thread ready to run. "
             "Initializing graphics H/W...");

     // we only support one display currently
     int dpy = 0;

     {
         // initialize the main display
         GraphicPlane& plane(graphicPlane(dpy));
         DisplayHardware* const hw = new DisplayHardware(this, dpy);
         plane.setDisplayHardware(hw);
     }

     // create the shared control-block
     mServerHeap = new MemoryHeapBase(4096,
             MemoryHeapBase::READ_ONLY, "SurfaceFlinger read-only heap");
     LOGE_IF(mServerHeap==0, "can't create shared memory dealer");

     mServerCblk = static_cast<surface_flinger_cblk_t*>(mServerHeap->getBase());
     LOGE_IF(mServerCblk==0, "can't get to shared control block's address");

     new(mServerCblk) surface_flinger_cblk_t;

     // initialize primary screen
     // (other display should be initialized in the same manner, but
     // asynchronously, as they could come and go. None of this is supported
     // yet).
     const GraphicPlane& plane(graphicPlane(dpy));
     const DisplayHardware& hw = plane.displayHardware();
     const uint32_t w = hw.getWidth();
     const uint32_t h = hw.getHeight();
     const uint32_t f = hw.getFormat();
     hw.makeCurrent();

     // initialize the shared control block
     mServerCblk->connected |= 1<<dpy;
     display_cblk_t* dcblk = mServerCblk->displays + dpy;
     memset(dcblk, 0, sizeof(display_cblk_t));
     dcblk->w            = plane.getWidth();
     dcblk->h            = plane.getHeight();
     dcblk->format       = f;
     dcblk->orientation  = ISurfaceComposer::eOrientationDefault;
     dcblk->xdpi         = hw.getDpiX();
     dcblk->ydpi         = hw.getDpiY();
     dcblk->fps          = hw.getRefreshRate();
     dcblk->density      = hw.getDensity();

     // Initialize OpenGL|ES
     glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
     glPixelStorei(GL_PACK_ALIGNMENT, 4);
     glEnableClientState(GL_VERTEX_ARRAY);
     glEnable(GL_SCISSOR_TEST);
     glShadeModel(GL_FLAT);
     glDisable(GL_DITHER);
     glDisable(GL_CULL_FACE);

     const uint16_t g0 = pack565(0x0F,0x1F,0x0F);
     const uint16_t g1 = pack565(0x17,0x2f,0x17);
     const uint16_t wormholeTexData[4] = { g0, g1, g1, g0 };
     glGenTextures(1, &mWormholeTexName);
     glBindTexture(GL_TEXTURE_2D, mWormholeTexName);
     glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
     glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
     glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
     glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 2, 2, 0,
             GL_RGB, GL_UNSIGNED_SHORT_5_6_5, wormholeTexData);

     const uint16_t protTexData[] = { pack565(0x03, 0x03, 0x03) };
     glGenTextures(1, &mProtectedTexName);
     glBindTexture(GL_TEXTURE_2D, mProtectedTexName);
     glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
     glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
     glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
     glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 1, 1, 0,
             GL_RGB, GL_UNSIGNED_SHORT_5_6_5, protTexData);

     glViewport(0, 0, w, h);
     glMatrixMode(GL_PROJECTION);
     glLoadIdentity();
     // put the origin in the left-bottom corner
     glOrthof(0, w, 0, h, 0, 1); // l=0, r=w ; b=0, t=h

     mReadyToRunBarrier.open();

     /*
      *  We're now ready to accept clients...
      */

     // start boot animation
     property_set("ctl.start", "bootanim");

     return NO_ERROR;
 }

2. SurfaceFlinger::threadLoop

       Surfaceflinger的loop函数，主要是等待其他接口发送的event，进行显示数据的合成以及显示。

 bool SurfaceFlinger::threadLoop()
 {
     waitForEvent();  //等待其他接口的signal event

     // post surfaces (if needed)
     handlePageFlip();   //处理翻页机制

     if (UNLIKELY(mHwWorkListDirty)) {
         // build the h/w work list
         handleWorkList();
     }

     const DisplayHardware& hw(graphicPlane(0).displayHardware());
     if (LIKELY(hw.canDraw())) {
         // repaint the framebuffer (if needed)

         const int index = hw.getCurrentBufferIndex();
         GraphicLog& logger(GraphicLog::getInstance());

         logger.log(GraphicLog::SF_REPAINT, index);
         handleRepaint(); //合并所有layer并填充到buffer中去

         // inform the h/w that we're done compositing
         logger.log(GraphicLog::SF_COMPOSITION_COMPLETE, index);
         hw.compositionComplete();

         logger.log(GraphicLog::SF_SWAP_BUFFERS, index);
         postFramebuffer();  //互换front buffer和back buffer，调用EGL接口进行显示

         logger.log(GraphicLog::SF_REPAINT_DONE, index);
     } else {
         // pretend we did the post
         hw.compositionComplete();
         usleep(16667); // 60 fps period,每秒刷新60次
     }
     return true;
 }

3. SurfaceFlinger::createSurface 

      提供给应用程序的主要接口，该接口可以创建一个surface，底层会根据参数创建layer以及分配内存（共2个buffer：front/back buffer），surface相关参数会反馈给上层。 

 sp<ISurface> SurfaceFlinger::createSurface(
         ISurfaceComposerClient::surface_data_t* params,
         const String8& name,
         const sp<Client>& client,
         DisplayID d, uint32_t w, uint32_t h, PixelFormat format,
         uint32_t flags)
 {
     sp<LayerBaseClient> layer;
     sp<ISurface> surfaceHandle;

     if (int32_t(w|h) < 0) {
         LOGE("createSurface() failed, w or h is negative (w=%d, h=%d)",
                 int(w), int(h));
         return surfaceHandle;
     }

     //LOGD("createSurface for pid %d (%d x %d)", pid, w, h);
     sp<Layer> normalLayer;
     //创建layer，根据参数（宽高格式）分配内存（共2个buffer：front/back buffer）
     switch (flags & eFXSurfaceMask) {
         case eFXSurfaceNormal:
             normalLayer = createNormalSurface(client, d, w, h, flags, format);
             layer = normalLayer;
             break;
         case eFXSurfaceBlur:
             // for now we treat Blur as Dim, until we can implement it
             // efficiently.
         case eFXSurfaceDim:
             layer = createDimSurface(client, d, w, h, flags);
             break;
         case eFXSurfaceScreenshot:
             layer = createScreenshotSurface(client, d, w, h, flags);
             break;
     }

     if (layer != 0) {
         layer->initStates(w, h, flags);
         layer->setName(name);
         ssize_t token = addClientLayer(client, layer);

         //创建surface
         surfaceHandle = layer->getSurface();
         if (surfaceHandle != 0) {
             params->token = token;
             params->identity = layer->getIdentity();
             if (normalLayer != 0) {
                 Mutex::Autolock _l(mStateLock);
                 mLayerMap.add(layer->getSurfaceBinder(), normalLayer);
             }
         }

         setTransactionFlags(eTransactionNeeded);
     }

     return surfaceHandle;
 }

 4. SurfaceFlinger::setTransactionState

处理上层的各个命令，并根据flag设置event通知Threadloop进行处理。

 void SurfaceFlinger::setTransactionState(const Vector<ComposerState>& state,
         int orientation) {
     Mutex::Autolock _l(mStateLock);

     uint32_t flags = 0;
     if (mCurrentState.orientation != orientation) {
         if (uint32_t(orientation)<=eOrientation270 || orientation==42) {
             mCurrentState.orientation = orientation;
             flags |= eTransactionNeeded;
             mResizeTransationPending = true;
         } else if (orientation != eOrientationUnchanged) {
             LOGW("setTransactionState: ignoring unrecognized orientation: %d",
                     orientation);
         }
     }

     const size_t count = state.size();
     for (size_t i=0 ; i<count ; i++) {
         const ComposerState& s(state[i]);
         sp<Client> client( static_cast<Client *>(s.client.get()) );
         flags |= setClientStateLocked(client, s.state);
     }
     if (flags) {
         setTransactionFlags(flags);
     }

     signalEvent();

     // if there is a transaction with a resize, wait for it to
     // take effect before returning.
     while (mResizeTransationPending) {
         status_t err = mTransactionCV.waitRelative(mStateLock, s2ns(5));
         if (CC_UNLIKELY(err != NO_ERROR)) {
             // just in case something goes wrong in SF, return to the
             // called after a few seconds.
             LOGW_IF(err == TIMED_OUT, "closeGlobalTransaction timed out!");
             mResizeTransationPending = false;
             break;
         }
     }
 }

5. SurfaceFlinger::composeSurfaces

      该接口在threadLoop->handleRepaint中被调用，负责将所有存在的surface进行合并，OpenGL模块负责这个部分。

6. SurfaceFlinger::postFramebuffer

      该接口在threadLoop中被调用，负责将合成好的数据（存在于back buffer中）推入front buffer中，然后调用HAL接口命令底层显示。 

 7. surface与layer

     从3中可知，上层每创建一个surface的时候，底层都会同时创建一个layer，下面看一下surface及layer的相关属性。

Note：code中相关结构体太大，就不全部罗列出来了

A、Surface相关属性（详细参考文件surface.h）

      a1：SurfaceID：根据此ID把相关surface和layer对应起来

      a2：SurfaceInfo   包括宽高格式等信息

      a3：2个buffer指针、buffer索引等信息

B、Layer相关属性（详细参考文件layer.h/layerbase.h/layerbitmap.h）

      包括Layer的ID、宽高、位置、layer、alpha指、前后buffer地址及索引、layer的状态信息（如eFlipRequested、eBusy、eLocked等）

待续。。。