Baby X is an open source, portable GUI toolkit aimed at smaller programs.
The idea is that Baby X programs will run on any major operating system, just by linking the correct version of the Baby X library. Currently we only support Linux (X Windows) and Microsoft Windows, but the aim is that Baby X programs should be easily portable to any environment, simply by rewriting the OS-specific portions oof the library.
The code is separated into several sections. At the lowest level, is the operating system specific layer. These are in the directories "windows" and "linux". Then at the next level is the core library, in the directory "common". This contains all of the simple widgets that can be written portably, plus the portable utility code. Then there is the widgets library, containing complicated widgets that are built on top of the other Baby X widgets. Finally we have the user programs. Some example programs are packaged with the Baby X distribution to provide a reference code base and to test how the library stand up to real life.
The code is all written in portable ANSI C, except for the operating system specific parts. We don't use derived types, most of the variables are simple ints, doubles, unsigned char, or char *s. We don't use const because it is not always obvious whether a Baby X function should make a chnage in an object or not. The structures are mostly opaque, created on the heap, and passed around by pointer.
The Baby X namespace is BBX_ for structures and internal functions, and bbx_ for user-callable functions, with a few exceptions such as the BABYX connection itself. Every fucntion prefixed BBX_ is operating system-specific and should not be called by user code. There is one header for all of the core library, which is "BabyX.h". This includes windows.h or X11/Xlib.h, so user programs should be careful not to use sysmbols which clash.
Baby X relies heavily on callback functions. Virtually all the widgets accept callbacks. Often these can be null because the sae information can be got by querying the widget. For example, a BBX_CheckBox can call a callback when it changes state, but it will usually be easier simply to query its tick state on dialog close, or if data is required. The callback always passes back a context pointer, which can be null, but means that there is no need for globals. Most of the widgets are BBX_Panels, and hnag widget-specific data off the panels' context pointer.
Destruction needs to be explicit and it reverse order of window hierarchy.
There is a simple graphicssupport library which is used internally by the core widgets to draw themselves. There is also a complicated graphicscontext which user programs can use to draw vector-style graphics. However because all graphics are implemented by drawing to rgba buffers, any graphics system can work alongside Baby X. The graphics context can also be taken and used in non-Baby X programs.
Text is handled as UTF-8. There is no support for right to left language such as Hebrew or Arabic, or for composite glyphs. Fonts are pre-rasterised, by the Baby X resource compiler.
There are two fonts currently packaged with the Baby X core library, the default gui font and the user font. the user font is monospaced.
Baby X is a "baby" toolkit. So currently there is no way to customise the appearance of most of the controls. Everything is grey, with light coming from the upper left. More customisation will be added as the library develops. However the goal is to keep it simple, and consistent.
The Baby X recource compiler, babyxrc, is designed to be used with Baby X programs. It packages assets as C source files for inclusion in Baby X programs. It's also a treasury of protable ANSI C code for parsing file formats that can be used in other projects. Plus the resource compiler is not only useful for Baby X, you might want it for your embedded project.
There are three "real" user programs, BabyBridge - a contract bridge game, BabyPerlin, a Perlin noise texture generator, and WordCatch, a game in which you try to spell words by catching falling letters. WordCatch shows off the simplicity of Baby X's graphics. It simply creates a full canvas covering the window, then draws rgba objects to it.
Current priorities are to get the documentation ready, and to improve the appearance of the Baby X widgets. The next thing is to get the audio system working. As a longer term goal, it should also be ported to Apple. We're always glad to receive help, feedback, suggestions, or Baby X programs that users have written.
Enjoy Baby X.