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……