Re: Backend Docs (Was: GNUstep Window Manager (was RE: Idea))

[Richard Frith-Macdonald]

On Monday, January 8, 2001, at 07:09 AM, Sungjin Chun wrote:

> Hi, 
>  
> That's the problem; we have almost no documentation or 
> information on how to make a backend system and how 
> currnet backend system works. Yes, I can refer the source code 
> but it's too much for me T_T. Any suggestion or correction? 

Sorry - last post .. I have to go catch a train soon, but I'll try to collect 
email this evening.

The backend has two aspects 
1. Event handling - uses NSRunLoop to watch the system and creates NSEvents that
it passes to the frontend.
2. Drawing/window management - a cut-down, dps-like API.

These are mediated by the NSgraphicsContext class - each backend provides its 
own
subclass of this.
The drawing functions are implemented as inline functions that reference through
a lookup table to call the objc methods of the graphics context without the 
overheads of going through the objc runtime, and are therefore pretty efficient.

The header files to look at are
NSGraphicsContext.h (the claass) and PSOperators.h, DPSOperators.h (inline 
functions)

The backend provides the implementation for the stuff declared in these headers.