OpenGL上下文和设备上下文如何工作？

I'm new to U/I programming, and I'm trying to get started with OpenGL. When I run an example program which creates a new OpenGL window with GLUT, it works fine. Good. However, in the context of another program, where I have to respond to Draw events (on Windows), with a device context passed to me - and where I might not have GLUT available - my confusion is this:I'm new to U/I programming, and I'm trying to g