surfaceflinger刷新动作和client合成

首先来看看,createlayer这个是后面刷新的基本。createsurface生成surface的时候会调用createlayer

status_t SurfaceFlinger::createLayer(
        const String8& name,
        const sp<Client>& client,
        uint32_t w, uint32_t h, PixelFormat format, uint32_t flags,
        uint32_t windowType, uint32_t ownerUid, sp<IBinder>* handle,
        sp<IGraphicBufferProducer>* gbp, sp<Layer>* parent)
{
   
    if (int32_t(w|h) < 0) {
   
        ALOGE("createLayer() failed, w or h is negative (w=%d, h=%d)",
                int(w), int(h));
        return BAD_VALUE;
    }

    status_t result = NO_ERROR;

    sp<Layer> layer;

    String8 uniqueName = getUniqueLayerName(name);

	//创建layer
    switch (flags & ISurfaceComposerClient::eFXSurfaceMask) {
   
        case ISurfaceComposerClient::eFXSurfaceNormal:
            result = createNormalLayer(client,
                    uniqueName, w, h, flags, format,
                    handle, gbp, &layer);
            break;
        case ISurfaceComposerClient::eFXSurfaceDim:
            result = createDimLayer(client,
                    uniqueName, w, h, flags,
                    handle, gbp, &layer);
            break;
        default:
            result = BAD_VALUE;
            break;
    }

    if (result != NO_ERROR) {
   
        return result;
    }

    // window type is WINDOW_TYPE_DONT_SCREENSHOT from SurfaceControl.java
    // TODO b/64227542
    if (windowType == 441731) {
   
        windowType = 2024; // TYPE_NAVIGATION_BAR_PANEL
        layer->setPrimaryDisplayOnly();
    }

    layer->setInfo(windowType, ownerUid);

	//将layer增加到mCurrentState的layer向量里面
    result = addClientLayer(client, *handle, *gbp, layer, *parent);
    if (result != NO_ERROR) {
   
        return result;
    }
    mInterceptor.saveSurfaceCreation(layer);

    setTransactionFlags(eTransactionNeeded);
    return result;
}
status_t SurfaceFlinger::addClientLayer(const sp<Client>& client,
        const sp<IBinder>& handle,
        const sp<IGraphicBufferProducer>& gbc,
        const sp<Layer>& lbc,
        const sp<Layer>& parent)
{
   
    // add this layer to the current state list
    {
   
        Mutex::Autolock _l(mStateLock);
        if (mNumLayers >= MAX_LAYERS) {
   
            ALOGE("AddClientLayer failed, mNumLayers (%zu) >= MAX_LAYERS (%zu)", mNumLayers,
                  MAX_LAYERS);
            return NO_MEMORY;
        }
        if (parent == nullptr) {
   
        	//增加到向量里面，后面能得到的layer都是从这里来的
            mCurrentState.layersSortedByZ.add(lbc);
        } else {
   
            if (mCurrentState.layersSortedByZ.indexOf(parent) < 0) {
   
                ALOGE("addClientLayer called with a removed parent");
                return NAME_NOT_FOUND;
            }
            parent->addChild(lbc);
        }

        mGraphicBufferProducerList.add(IInterface::asBinder(gbc));
        mLayersAdded = true;
        mNumLayers++;
    }

    // attach this layer to the client
    client->attachLayer(handle, lbc);

    return NO_ERROR;

在创建surface时候会创建layer同时会保存到mCurrentState里面

２.handleMessageRefresh

void SurfaceFlinger::handleMessageRefresh() {
   
    ATRACE_CALL();

    mRefreshPending = false;

    nsecs_t refreshStartTime = systemTime(SYSTEM_TIME_MONOTONIC);

    preComposition(refreshStartTime);
    rebuildLayerStacks();
    setUpHWComposer();
    doDebugFlashRegions();
    doComposition();
    postComposition(refreshStartTime);

    mPreviousPresentFence = mHwc->getPresentFence(HWC_DISPLAY_PRIMARY);

    mHadClientComposition = false;
    for (size_t displayId = 0; displayId < mDisplays.size