struct CallbackTranslation {
    TransactionCompletedCallback callbackFunction;
    std::unordered_map<sp<IBinder>, sp<SurfaceControl>, SurfaceComposerClient::IBinderHash>
            surfaceControls;
};

• TransactionCompletedCallback 是一个函数指针类型。

  using TransactionCompletedCallback =
          std::function<void(nsecs_t /*latchTime*/, const sp<Fence>& /*presentFence*/,
                             const std::vector<SurfaceControlStats>& /*stats*/)>;
  

• surfaceControls 的 key 是 SurfaceControl::mHandle。

CallbackTranslation 作为 TransactionCompletedListener::mCallbacks 的 value 类型，key 是 CallbackId。

std::unordered_map<CallbackId, CallbackTranslation, CallbackIdHash> mCallbacks
        GUARDED_BY(mMutex);