Creating Graphical Interfaces

• When it comes to creating GUIs, Linux programmers have more options available than they do for creating TUIs. Probably the most popular and certainly the best known toolkits used to create graphical applications are Qt and GTK+.
  • Qt is the C++ application framework that powers KDE, the K Desktop Environment.
  • GTK+ is the toolkit underneath GNOME, the GNU Network Object Model Environment. GTK+ is written largely in C, but it has language bindings available for many other programming languages, such as Perl, C++, and Python, so you can use GTK+ features in many programming environments.
• There are many other toolkits, frameworks, and libraries that you can use to develop GUIbased applications for Linux. The following list, arranged alphabetically, describes some of the most common ones. Most of these toolkits and frameworks describe widget sets, which are implemented in one or more programming libraries. Widget is the term applied to a user interface abstraction, such as a scrollbar or a button, created using the toolkit.
  • Athena; The Athena library was one of the earliest widget libraries available for the X Window System. It was a thin layer of abstraction on top of raw Xlib calls that made it slightly less painful to create scrollbars, text entry boxes, and other typical GUI elements. It is part of the standard X11 distribution.
  • 3-D Athena Toolkit; The 3D Athena Toolkit was a 3D version of the original Athena toolkit. It gave Athena a 3D look and was a considerable visual improvement over plain vanilla Athena. The 3D Athena toolkit, although no longer widely used.
  • FLTK; FLTK, which is pronounced ``full tick'' is an acronym for the Fast Light Toolkit. FLTK is a GUI for X, Mac OS X, and Microsoft Windows. Written in C++, FLTK makes it possible to write GUIs that look almost identical regardless of the platform on which the GUI runs. FLTK also supports OpenGL graphics.
  • XForms; XForms is a GUI toolkit based on Xlib. It isn't highly configurable like the other GUI toolkits discussed in this section, but its simplicity makes XForms easier to use than the other graphical toolkits. It comes with a GUI builder that makes it fast and easy to get working application up and running.
  • OpenGL; OpenGL is the industry-standard 3D graphics toolkit. It provides the most realistic and lifelike graphics currently available for the X Window System. It is generally available as part of XFree86.
  • Motif; Motif was one of the first widget or interface toolkits available for the X Window System that combined both an interface toolkit and a window manager. Originally available only as a commercial product, it is now available in an open source version.
  • Xlib; Xlib is shorthand for the X library, a low-level, C-based interface to the raw X Window System protocol. If you want to write as close to the X graphics core as possible, you write Xlib-based programs. Indeed, most window managers, widget libraries, and GUI toolkits are written using Xlib function. While using straight Xlib gives you the best performance, it is extremely code intensive. Xlib is an essential ingredient of the standard X distribution.
  • Xt; Xt Intrinsics are a very thin layer of functions and data structures on top of Xlib. Xt Intrinsics create an object-oriented interface that C programs can use to create graphical elements. Without other widget sets, the Intrinsics are not especially useful. Xt, like Xlib, is a part of the standard X distribution and is not available separately.