connect(camera, static_cast
    
     (&QCamera::lockStatusChanged),      [=](QCamera::LockStatus status, QCamera::LockChangeReason reason){ /* ... */ });static_cast
     
      (&QCamera::lockStatusChanged)上面这句是一个静态转换 static_cast<>()QCamera::* 是类指针QCamera::LockStatus 函数参数QCamera::LockChangeReason 函数参数&QCamera::lockStatusChanged 函数地址