A Standard for Application Starters

Mr. Anastácio demonstrates how to write an application starter in a standard format.

by Rui Anastácio

Most X users start applications from an X terminal. To do this, you must know the names of the programs, pass parameters each time you run them and include the programs in your search path.

Instead of calling applications from the terminal, you can use an application starter, a program that shows a list or menu of installed applications and lets you choose the one to start. Some starters show pretty icons and are very appealing with features like clocks, load meters, etc.

The problem is that each starter has a different way of describing the list of installed applications. Usually, this information is written in a text file in some format. For example, the starter of FVWM reads the .fvwmrc file for this information. Other window managers (WM) use different formats and files. If you use various WMs, things can get a bit messy.

Creating a standard format, location and name for application starters simplifies the process of creating, changing and exchanging information. Another advantage is in program installation. The installation process can read this file (open format and location) and automatically add the necessary entries to access the installed components. For example, when installing StarOffice, it would be nice if a group called StarOffice was created automatically with scalc, swrite and the rest.

This article proposes a standard format and a standard location for this application starter file and presents QStart, a starter which I have written (using the Qt Toolkit) in this format.

The File Format

The file, plain ASCII, consists of two parts: configuration parameters and menu definition.

The first part is used to define parameters, such as the directory in which icons are located. Each line starts with a reserved keyword, followed by the necessary parameters separated by a semicolon:

ReservedWord param1;param2;...;paramN

Only one standard reserved word, IconDir dir, is defined in which dir is the directory where the starter searches for the icons referred to in the Menu Definition.

Other reserved words can be added for different starters. For QStart, I have defined one more word (see next section).

As an example, the next lines can be used to configure QStart to search the icons in /usr/local/icons and place the button, which pops up the menu, at position 0,0 of the screen.

IconDir /usr/local/icons
Position 0;0

To avoid future problems, consider carefully whether to add new reserved words. My idea with standard words is that these are words which are absolutely necessary to any application starter.

As new starters arrive, new words will appear. It might be a good idea to use generic words. Here are some ideas:

ConfigFile file: define a specific file for extra, specific configuration.
Show elem1;elem2;...: show a clock or the work areas in the starter, for example Show Clock;WorkArea;IconsOnly.
Style style: use a different style to show the list of applications, for example Style Modern.

In order to keep track of future development, I have mounted a site at http://w3.ualg.pt/~ranasta/starter/ to centralize all related information.

The second part is the menu definition with the same syntax: a reserved word at the start of the line, followed by the parameters separated by a semicolon. All the applications are defined inside groups or menus. The main menu has the name ``Main'' and is the starting point. The menu name, or id, should be interpreted in a case insensitive manner; that is, writing ``Main'', ``MAIN'' or ``main'' should have the same effect. The reserved words should be interpreted in the same manner. Starting and ending a menu definition are the reserved words Menu and End.

Menu

Here, id is the name of the menu for internal identification; the menu with an id of main is the starting point. title is the title of the menu and icon is the icon file name.

Between Menu and End are menu items:

Separator: draw a separator, normally a horizontal line.
Text text: draw the text.
Image filename: draw the image stored in filename.
Program text;icon;command: an application. text is the text that appears on the menu entry; icon is the associated icon; command is the command invoked when this option is called.
SubMenu id: an entry point to menu id. The title and icon of the menu id should appear as data to this entry.

Two examples of Menu blocks are shown here:

Menu Main;Applications;apps.xbm
 Program Terminal;xterm.xbm;xterm
 Program Editor;edit.xmb;nedit
 Separator
 Text Groups
 SubMenu Graphics
End

Menu Graphics;Graphics;graph.xbm
 Text Image
 Program GIMP;gimp.xbm;gimp
 Program Paint;paint.xbm;paint
 Separator
 Text Draw
 Program tgif;tgif.xbm;tgif
End

The File Name and Location

In order for programs to know where to look for this file, it must have a standard name and location. The name is .apps and the location is found in this way. First, the home directory is searched so that different users can have different configurations. Next, the system directory /usr/local is searched. This is the default configuration for all users, and can be managed by the system administrator.

QStart

Most of my experience in GUI programming has been with Motif, Xforms and TclTk. To write Qstart, I chose to use QT because it is available for many platforms and is a powerful toolkit. Also, by choosing QT, I got to learn something new.

QStart reads the .apps file from the standard location. The icon of the main menu is displayed on-screen at the position indicated by the reserved word ``Position'' as a button. When you press this button with the left mouse button, the applications pop-up menu will appear and the list is shown. (See Figure 1.) Pressing the right mouse button pops up a configuration menu. This menu has the options Quit and Restart. Quit does just that; Restart runs the QStart program (have it in your path) and then quits. These are useful options when you make changes to the .apps file; calling restart automatically updates the applications list.

Figure 1. Applications Menu

QStart defines the following reserved word: Position x;y. This uses x,y as the position on the screen for the button which pops up the menu.

Qstart can be found in the archive file http://w3.ualg.pt/~ranasta/starter/qstart/qstart-1.0.tgz. This includes both binaries and source. Anyone interested is encouraged to use this code to build better starters.

The Future

Here are some points to think about for the future:

A stable format for this file
New starters built using this format--prettier, more efficient, etc.
Installation programs which automatically add entries for the installed components
Creation of a set of routines to facilitate the installation programs finding, changing, adding and deleting entries in the file
Support of this format in existing window managers

The future is unknown, but we can shape it or at least give it a try.

Rui Anastácio is currently teaching mathematics and computer science at Escola Superior de Tecnologia--Universidade do Algarve and uses Linux for part of his work. His free time is spent in sports such as tennis, table tennis, bicycling, jogging, kung fu, swimming and others. He also likes good books, music, photography, traveling and programming. He can be reached via e-mail at ranasta@ualg.pt.