xxl: A Free Spreadsheet for Linux

xxl is the fruit of a long-term student project of the “Maitrise d'Informatique” at the University of Nice-Sophia Antipolis in France. The intent of xxl is to produce a graphical spreadsheet which is both uncomplicated and easy to learn and use. xxl, along with the STk and TkTable packages upon which it depends, are freely available, open-source software. The license terms are similar to those accompanying the Tcl/Tk software.

Figure 1. xxl Toolbar

This spreadsheet is not completely self-contained. It needs a working installation of STk, a variation of the Tk toolkit which uses the Scheme programming language as a command interpreter instead of the usual Tcl. The TkTable widget library (which gives Tk the ability to display data in a tabular format) is included with the xxl distribution.

xxl is not designed to load or save files in the proprietary formats used by commercial spreadsheets. Files can be saved in four formats: HTML, plaintext, LaTeX and CSV (comma-separated values). The CSV format is supported by many commercial spreadsheets; it is sort of a least-common-denominator ASCII text data format which uses new lines to distinguish the rows and commas to separate the columns.

xxl does not install quickly, due to its dependence on the STk package. STk can be obtained from http://kaolin.unice.fr/STk/ in both source and binary formats; the source code is preferable, since it will most likely be the latest version. Luckily, STk is not at all difficult to build. Before installing xxl, it is a good idea to try out the test programs in the /Tests subdirectory of the STk source distribution, just to be sure it is working correctly.

Once STk is up and running, compiling and installing xxl is relatively easy. A configure script adapts the Makefile to your system, and there really isn't much code to be compiled. Most of xxl (aside from the TkTable library and a few other small shared libraries) is in the form of STk and STklos scripts, which are written in Scheme. The make install copies the xxl files to /usr/local/lib/xxl. In order to be able to run xxl from any directory, I created a symbolic link from xxl.stk to /usr/local/bin/xxl. Make sure you save a copy of the sole documentation file, xxl.doc.ps, and the files in the /Tests subdirectory, which are example spreadsheets saved in various formats. These files are helpful as examples while learning the application.

In order to make full use of this spreadsheet, a TeX and LaTeX installation is also needed. Although xxl can save files in other formats, the LaTeX format enables high-quality PostScript versions of files to be created, which are well-suited for printing.

When xxl starts up, two windows are created. The larger one is the spreadsheet and the other is an independent control window containing the icons and menus. Small “balloon help” messages appear above each icon when a mouse cursor lingers over it. At first glance, I thought I would be able to create a simple spreadsheet without consulting the documentation, but after several fruitless attempts to enter the formula for the sum of a column, I finally read the PostScript documentation.

Figure 2. xxl Screenshot

My assumption that simply clicking on the icon would be enough to sum cell values was wrong; doing this will enter part of what is needed into the command-input entry field, but the remainder has to be entered manually. Clicking the icon will enter sum(, but what is needed is (as an example) =sum(B2:B8). This has to be done only once, as the copy-and-paste key bindings can copy a formula from one cell and paste it into another; the column location is automatically changed to accommodate the new location. Columns are automatically recalculated when entries are added or changed.

xxl has some useful mouse-based features. Clicking button two on a cell border allows the cell to be dynamically resized. Cutting, copying and pasting of cell values is analogous to the standard x-selection method.

The font, font size and style of either individual cells or selected groups of cells can be set from the control bar. Currently, no support exists for graphing or charting of the spreadsheet data. A wide variety of mathematical, statistical and Boolean functions can be applied to selected cells or columns, but as with the above “sum cell values” example, only a bare skeleton of the required formula command is entered into the command entry field. The remainder needs to be entered by hand, but thereafter the formula can be easily copied and pasted into other cells. Any row or column can be “stuck” in place, which is typically used for identification text at the left and top. These fixed rows and columns will remain visible when a spreadsheet is scrolled.

Several sample spreadsheets are included with the xxl source. I found these to be at least as useful as the documentation while learning to create a spreadsheet with xxl. Load one of these examples into the main window, then select one of the cells and the formula which produced it will be shown in the input entry field.