android Gui系统之SurfaceFlinger(1)---SurfaceFlinger概论【转】

FramebufferNativeWindow::FramebufferNativeWindow() 
    : BASE(), fbDev(0), grDev(0), mUpdateOnDemand(false)
{
    hw_module_t const* module;
    if (hw_get_module(GRALLOC_HARDWARE_MODULE_ID, &module) == 0) {
        int stride;
        int err;
        int i;
        err = framebuffer_open(module, &fbDev);
        ALOGE_IF(err, "couldn‘t open framebuffer HAL (%s)", strerror(-err));
        
        err = gralloc_open(module, &grDev);
        ALOGE_IF(err, "couldn‘t open gralloc HAL (%s)", strerror(-err));

        // bail out if we can‘t initialize the modules
        if (!fbDev || !grDev)
            return;
        
        mUpdateOnDemand = (fbDev->setUpdateRect != 0);
        
        // initialize the buffer FIFO
        if(fbDev->numFramebuffers >= MIN_NUM_FRAME_BUFFERS &&
           fbDev->numFramebuffers <= MAX_NUM_FRAME_BUFFERS){
            mNumBuffers = fbDev->numFramebuffers;
        } else {
            mNumBuffers = MIN_NUM_FRAME_BUFFERS;
        }
        mNumFreeBuffers = mNumBuffers;
        mBufferHead = mNumBuffers-1;

        /*
         * This does not actually change the framebuffer format. It merely
         * fakes this format to surfaceflinger so that when it creates
         * framebuffer surfaces it will use this format. It‘s really a giant
         * HACK to allow interworking with buggy gralloc+GPU driver
         * implementations. You should *NEVER* need to set this for shipping
         * devices.
         */
#ifdef FRAMEBUFFER_FORCE_FORMAT
        *((uint32_t *)&fbDev->format) = FRAMEBUFFER_FORCE_FORMAT;
#endif

        for (i = 0; i < mNumBuffers; i++)
        {
                buffers[i] = new NativeBuffer(
                        fbDev->width, fbDev->height, fbDev->format, GRALLOC_USAGE_HW_FB);
        }

        for (i = 0; i < mNumBuffers; i++)
        {
                err = grDev->alloc(grDev,
                        fbDev->width, fbDev->height, fbDev->format,
                        GRALLOC_USAGE_HW_FB, &buffers[i]->handle, &buffers[i]->stride);

                ALOGE_IF(err, "fb buffer %d allocation failed w=%d, h=%d, err=%s",
                        i, fbDev->width, fbDev->height, strerror(-err));

                if (err)
                {
                        mNumBuffers = i;
                        mNumFreeBuffers = i;
                        mBufferHead = mNumBuffers-1;
                        break;
                }
        }

        const_cast<uint32_t&>(ANativeWindow::flags) = fbDev->flags; 
        const_cast<float&>(ANativeWindow::xdpi) = fbDev->xdpi;
        const_cast<float&>(ANativeWindow::ydpi) = fbDev->ydpi;
        const_cast<int&>(ANativeWindow::minSwapInterval) = 
            fbDev->minSwapInterval;
        const_cast<int&>(ANativeWindow::maxSwapInterval) = 
            fbDev->maxSwapInterval;
    } else {
        ALOGE("Couldn‘t get gralloc module");
    }

    ANativeWindow::setSwapInterval = setSwapInterval;
    ANativeWindow::dequeueBuffer = dequeueBuffer;
    ANativeWindow::queueBuffer = queueBuffer;
    ANativeWindow::query = query;
    ANativeWindow::perform = perform;

    ANativeWindow::dequeueBuffer_DEPRECATED = dequeueBuffer_DEPRECATED;
    ANativeWindow::lockBuffer_DEPRECATED = lockBuffer_DEPRECATED;
    ANativeWindow::queueBuffer_DEPRECATED = queueBuffer_DEPRECATED;
}