上一篇文章介绍到，SurfaceComposerClient 中的 createSurface() 方法最终创建的是一个 Layer，这里我们接着看 Layer 的创建。

一、Layer创建

1、SurfaceFlinger.cpp 

源码位置：/frameworks/native/services/surfaceflinger/SurfaceFlinger.cpp

status_t SurfaceFlinger::createLayer(LayerCreationArgs& args, sp<IBinder>* outHandle,const sp<IBinder>& parentHandle, int32_t* outLayerId,const sp<Layer>& parentLayer, uint32_t* outTransformHint) {……status_t result = NO_ERROR;sp<Layer> layer;// 根据图层类型调用不同的创建函数switch (args.flags & ISurfaceComposerClient::eFXSurfaceMask) {case ISurfaceComposerClient::eFXSurfaceBufferQueue:case ISurfaceComposerClient::eFXSurfaceBufferState: {result = createBufferStateLayer(args, outHandle, &layer);// 用于跟踪缓冲区状态std::atomic<int32_t>* pendingBufferCounter = layer->get