Android surfaceflinger（3）-DisplayDevice封装

  上一篇文章介绍了HWComposer的创建及初始化，本文将根据上述创建的HWComposer封装出DisplayDevice对象进行分析。

1、引言

  在此之前已经分析了HWComposer，接下来继续分析SurfaceFlinger::init的后续操作

void SurfaceFlinger::init() {    //详见http://blog.csdn.net/marshal_zsx/article/details/78054285    mHwc = new HWComposer(this,*static_cast<HWComposer::EventHandler *>(this));    // initialize our non-virtual displays    for (size_t i=0 ; i<DisplayDevice::NUM_BUILTIN_DISPLAY_TYPES ; i++) {        DisplayDevice::DisplayType type((DisplayDevice::DisplayType)i);        if (mHwc->isConnected(i) || type==DisplayDevice::DISPLAY_PRIMARY) {            // All non-virtual displays are currently considered secure.            bool isSecure = true;            createBuiltinDisplayLocked(type);//见第2节            wp<IBinder> token = mBuiltinDisplays[i];            sp<IGraphicBufferProducer> producer;            sp<IGraphicBufferConsumer> consumer;            BufferQueue::createBufferQueue(&producer, &consumer,                    new GraphicBufferAlloc());//见第3节            sp<FramebufferSurface> fbs = new FramebufferSurface(*mHwc, i,consumer);//见第4节            int32_t hwcId = allocateHwcDisplayId(type);            sp<DisplayDevice> hw = new DisplayDevice(this,                    type, hwcId, mHwc->getFormat(hwcId), isSecure, token,                    fbs, producer,mRenderEngine->getEGLConfig());//见第5节            mDisplays.add(token, hw);        }    }    // start boot animation    startBootAnim();//见下一篇文章}

2、token创建

  Android6.0支持多屏显示，为了区分不同的屏幕，需要创建不同的token（即使每一块屏幕唯一对应一个IBinder）；并用mBuiltinDisplays数组进行管理，具体代码如下：

void SurfaceFlinger::createBuiltinDisplayLocked(DisplayDevice::DisplayType type) {    ALOGW_IF(mBuiltinDisplays[type],            "Overwriting display token for display type %d", type);    mBuiltinDisplays[type] = new BBinder();    DisplayDeviceState info(type);    // All non-virtual displays are currently considered secure.    info.isSecure = true;    mCurrentState.displays.add(mBuiltinDisplays[type], info);}

3、建立bufferqueue生产者消费者

void BufferQueue::createBufferQueue(sp<IGraphicBufferProducer>* outProducer,        sp<IGraphicBufferConsumer>* outConsumer,        const sp<IGraphicBufferAlloc>& allocator) {    LOG_ALWAYS_FATAL_IF(outProducer == NULL,            "BufferQueue: outProducer must not be NULL");    LOG_ALWAYS_FATAL_IF(outConsumer == NULL,            "BufferQueue: outConsumer must not be NULL");    sp<BufferQueueCore> core(new BufferQueueCore(allocator));    LOG_ALWAYS_FATAL_IF(core == NULL,            "BufferQueue: failed to create BufferQueueCore");    //创建生产者    sp<IGraphicBufferProducer> producer(new BufferQueueProducer(core));    LOG_ALWAYS_FATAL_IF(producer == NULL,            "BufferQueue: failed to create BufferQueueProducer");    //创建消费者    sp<IGraphicBufferConsumer> consumer(new BufferQueueConsumer(core));    LOG_ALWAYS_FATAL_IF(consumer == NULL,            "BufferQueue: failed to create BufferQueueConsumer");    *outProducer = producer;    *outConsumer = consumer;}

4、创建FramebufferSurface

FramebufferSurface::FramebufferSurface(HWComposer& hwc, int disp,        const sp<IGraphicBufferConsumer>& consumer) :    ConsumerBase(consumer),    mDisplayType(disp),    mCurrentBufferSlot(-1),    mCurrentBuffer(0),    mHwc(hwc){    mName = "FramebufferSurface";    mConsumer->setConsumerName(mName);    int usage = GRALLOC_USAGE_HW_FB | GRALLOC_USAGE_HW_RENDER |                                       GRALLOC_USAGE_HW_COMPOSER;    if(disp != 0) {        usage |= GRALLOC_USAGE_HW_FBX;    }    //mConsumer是父类ConsumerBase的成员变量，故以下是调用IGraphicBufferConsumer对应的方法    mConsumer->setConsumerUsageBits(usage);    mConsumer->setDefaultBufferFormat(mHwc.getFormat(disp));//设置buffer格式    mConsumer->setDefaultBufferSize(mHwc.getWidth(disp),  mHwc.getHeight(disp));//设置buffer大小    mConsumer->setDefaultMaxBufferCount(NUM_FRAMEBUFFER_SURFACE_BUFFERS);}

5、创建DisplayDevice

DisplayDevice::DisplayDevice(        const sp<SurfaceFlinger>& flinger,        DisplayType type,        int32_t hwcId,        int format,        bool isSecure,        const wp<IBinder>& displayToken,        const sp<DisplaySurface>& displaySurface,        const sp<IGraphicBufferProducer>& producer,        EGLConfig config)    : lastCompositionHadVisibleLayers(false),      mFlinger(flinger),      mType(type), mHwcDisplayId(hwcId),      mDisplayToken(displayToken),      mDisplaySurface(displaySurface),      mDisplay(EGL_NO_DISPLAY),      mSurface(EGL_NO_SURFACE),      mDisplayWidth(), mDisplayHeight(), mFormat(),      mFlags(),      mPageFlipCount(),      mIsSecure(isSecure),      mSecureLayerVisible(false),      mLayerStack(NO_LAYER_STACK),      mOrientation(),      mPowerMode(HWC_POWER_MODE_OFF),      mActiveConfig(0){    mNativeWindow = new Surface(producer, false);    ANativeWindow* const window = mNativeWindow.get();    /*     * Create our display's surface     */    EGLSurface surface;    EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY);    if (config == EGL_NO_CONFIG) {        config = RenderEngine::chooseEglConfig(display, format);    }    surface = eglCreateWindowSurface(display, config, window, NULL);    eglQuerySurface(display, surface, EGL_WIDTH,  &mDisplayWidth);    eglQuerySurface(display, surface, EGL_HEIGHT, &mDisplayHeight);    mConfig = config;    mDisplay = display;    mSurface = surface;    mFormat  = format;    mPageFlipCount = 0;    mViewport.makeInvalid();    mFrame.makeInvalid();    // virtual displays are always considered enabled    mPowerMode = (mType >= DisplayDevice::DISPLAY_VIRTUAL) ?                  HWC_POWER_MODE_NORMAL : HWC_POWER_MODE_OFF;    // Name the display.  The name will be replaced shortly if the display    // was created with createDisplay().    switch (mType) {        case DISPLAY_PRIMARY:            mDisplayName = "Built-in Screen";            break;        case DISPLAY_EXTERNAL:            mDisplayName = "HDMI Screen";            break;        default:            mDisplayName = "Virtual Screen";    // e.g. Overlay #n            break;    }    //初始化显示方向转换。    setProjection(DisplayState::eOrientationDefault, mViewport, mFrame);}

  创建DisplayDevice对象完成后，调用mDisplays.add(token, hw)加入到mDisplays键值容器中，这就形成了每个屏幕都有唯一指定的token。

6、总结与展望

  当surfaceflinger初始化完成后，就会去启动开机动画；后面将分析开机动画是如何与surfaceflinger进行交互的。未完待续……