Resources for Programming the Linux X-Server

Question

Are there any out there that are easy to get ahold of? Preferably free, as I don't have any money to spend right now.

What I'm trying to Accomplish

Basically, I'm writing a multi-platform application in native C/C++, and now that I have Linux installed, I feel as though I'm truly ready to make the "multi-platform" development go. Before anyone says "use SDL" or "Qt", note that I'm doing this for an application which I plan to go commercial with (Qt costs money for commercial applications). While SDL is good, I'm also looking to learn about window managers in general. I feel as though the best way to learn how to communicate directly with the operating system is to write the application yourself.

So, are there any resources out there?

Answer 1

First of all X-Windows has nothing to do with Linux.

X-Windows is both a graphical protocol and a GUI system built up around it. X runs on most OSes including Windows and Mac. The most typical scenario is for an X application to run on a multiuser computer running a UNIX-like OS (for instance Linux) and for the users to interact with it using an X-server which runs on either an X-terminal or a desktop OS. The X-Server is a standard piece of the X-System. If you install an X-Server on Windows then you will be able to interact with graphical applications running on one or more other computers.

It sounds like you want to focus on building the X applications, not the device drivers or the server or any other part of the X-system. Linux is as good a choice as any, but the books and documents that you need were likely written using Solaris or BSD UNIX. But it's the same API.

Since X has been widespread since at least the early 90's, look for books in secondhand shops and university jumble sales. Advertise on Craigslist for X related books.

The lowest level API for X is called Xlib. Toolkits like GTK and QT are layered on top of this so studying their code is a good way to learn how to do things. But there is also something called the X-Toolkit that runs over Xlib and used to be the foundation layer for GUI toolkits like Motif and others. If I were you I would start with X-Toolkit, to get familiar with all the component parts of X and how they interact. For instance, it will take you a while to get used to the fact that a window manager which manages the windows on an X-Server display, doesn't run on the X-server but runs on a remote system. Or that you can have apps running on Linux and OS/X and Solaris all displaying their windows on the X-server on a single Windows box.

Google X Toolkit intrinsics to get all kinds of info including free reference manuals.

As you read more about it you will come across a lot of other unique terms that you can google to get additional info and a broader perspective. Don't spend too much time with old toolkits like Athena Widgets or Motif.

Since there were more people programming X in the early days of the Internet than today, the USENET FAQs are still a good source of introductory tips, e.g. http://www.faqs.org/faqs/Xt-FAQ/

Answer 2

You can write your app as a server in C. Call it Engine. No need to think about the User Interface. After that you can create interface in Qt. The communication protocol will be public (or private) and your Qt application will be open-source. Later if you like you can create many more interface to your application. Such as web interface, Gnome interface, C#.NET interface etc.