Office42 Spreadsheet

Office42 Spreadsheet (the binary is office42, and that is one word: Office42) is a spreadsheet in the shape of Excel 5 and at parity with Gnumeric, written from scratch in C on GTK 4, Pango and Cairo. It is the sister project of word42, built on the same principles: a small, honest codebase that does one thing well. The site is office42.net.

docs/GUIDE.md is the user guide: every menu, every dialog, the number-format codes, the keyboard and the terminal front-end. docs/PARITY.md is a review of the code and an honest estimate of how far it is from Excel and from Gnumeric.

Goals

office42 aims at two programs:

• Gnumeric, for what a free spreadsheet should be able to do and for how to do it right. Gnumeric was built by people who cared about numerical correctness more than about features, and that is the standard to hold to.
• Microsoft Excel 5 (1993), for what it should look like and how it should behave: a grid, a formula bar, a name box, two toolbars and sheet tabs along the bottom. No ribbon.

What it does

The window. A grid of 1,048,576 rows by 16,384 columns, with Excel's keys: Enter steps down, Tab steps right and Tab-Tab-Enter returns to the column the row began in. The formula bar is the same edit as the cell, with every reference in its own colour; two letters into a function name the matching functions are listed, and inside a call the signature is shown with the argument you are on in bold. Point mode writes a reference by clicking a cell, and F4 cycles its dollars. The fill handle continues a series, dragging a selection moves it and every formula that pointed at it, and AutoComplete offers the text already in the column. Zoom, freeze panes, split panes, custom views, outline groups, a second window on the same book, and undo of everything, deleting a sheet included.

Formatting. Excel 5's tabbed Format Cells dialog: number formats in Excel's own code language (#,##0.00;[Red](#,##0.00), dddd d mmmm yyyy, [h]:mm), fonts, rich text with several fonts in one cell, borders of every style and colour, pattern fills, indent, rotation, merged cells, named cell styles that restyle every cell wearing them, and conditional formats. Formats are interned, so a thousand bold cells share one record.

Formulas. A parser with Excel's precedence, A1 and $A$1 references, ranges, whole rows and columns, array constants, 3-D references across sheets, structured references into tables, names, LET and LAMBDA. Array formulas with Ctrl+Shift+Enter and dynamic arrays that spill. Recalculation is demand-driven with dirty flags, and circular references are reported rather than followed. 637 functions: every one Excel 2003 has, the statistics computed in two passes so they are accurate, the distributions on regularised incomplete gamma and beta functions, the whole bond arithmetic on the five day-count bases, the .INTL dates, the text-splitting and array-cutting functions of Excel 365, and Gnumeric's own besides: the complex functions Excel leaves out, twenty-eight random distributions, number theory, FOURIER, HPFILTER, INTERPOLATION, PERIODOGRAM, the movable feasts and Black and Scholes with its Greeks.

Charts and objects. Column, bar, line, area, pie, doughnut, radar, bubble, stock, surface, box and whiskers, histogram, polar, contour and XY scatter charts, in two or three dimensions, with trendlines, error bars, a second value axis and chart sheets, redrawn from the cells every time they are painted. Pictures, shapes, text boxes, grouped objects, notes, hyperlinks and the nine form controls of Excel's Forms toolbar, each bound to a cell.

Data. Sort, Find and Replace, AutoFilter and Advanced Filter, Text to Columns, Remove Duplicates, Subtotals, Consolidate, Scenarios, Data Validation, Tables, Pivot Tables with calculated fields and page filters, Goal Seek, a Solver and the statistical analysis tools: descriptive statistics, correlation, covariance, regression, histogram, ANOVA, rank and percentile, moving average. Each is one undo step.

Files. Gnumeric's .gnumeric, which carries everything; Excel's .xlsx and .xls (BIFF8 out, BIFF5 and BIFF8 in), with formulas, styles, charts, shapes, tables, names and notes, opening in Excel, LibreOffice and Gnumeric; OpenDocument .ods, checked against LibreOffice both ways; and HTML, CSV, DIF, SYLK, LaTeX and Lotus 1-2-3. The zip and OLE2 containers are a few hundred lines each, so no library was added. Printing, print preview, page setup with headers and footers, and export and import of PDF.

Automation. Python instead of Visual Basic: a console with book and sheet bound, scripts kept in the file, a macro recorder that writes Python, =PY("expression") in a cell, and functions defined in Python that appear in the Function Wizard. A book that arrives with scripts offers to run them and never runs them by itself. A SQLite database can sit beside the book or inside it, queried from Data ▸ Get Data or from a cell with =SQLVALUE(...). See docs/PYTHON.md and docs/DATABASE.md.

Spelling with Hunspell, and the terminal. office42-calc drives the whole engine from stdin, which is how it is checked:

$ ./builddir/src/office42-calc
A1 = 10
A2 = 20
B1 = =SUM(A1:A2)*2
B1
B1      60      (=SUM(A1:A2)*2)
dump
      A             B
1     10            60
2     20

Not planned: the ribbon, Visual Basic, co-authoring, Power Query and the Quattro Pro and Applix formats. docs/ROADMAP.md says why.

Building

office42 needs a C11 compiler, Meson, Ninja, and GTK 4.10 or newer with Pango, Cairo and gdk-pixbuf. Importing PDF needs poppler-glib; without it office42 still builds and still exports PDF. Python (python3-embed), spelling (Hunspell) and the database (SQLite) are used if they are there and can be turned off with -Dpython=disabled, -Dspell=disabled and -Dsqlite=disabled. The toolbar icons are SVG, so gdk-pixbuf wants its SVG loader at run time (librsvg2-common on Debian and Ubuntu).

meson setup builddir
meson compile -C builddir
./builddir/src/office42            # the window
./builddir/src/office42-calc       # the engine, from a terminal

Per-platform dependency lists are the same as word42's; see its docs/BUILD.md. On Windows, build-aux/bundle-windows.sh gathers a tree that runs without MSYS2 and build-aux/pack-msix.sh makes the Microsoft Store package from it; docs/WINDOWS-STORE.md has the procedure.

office42 --screenshot out.png book.gnumeric renders the window to a PNG without a compositor or a person at the keyboard; --activate ACTION, --select B4, --type '=SU' and --keys down,tab,enter open a dialog, move the selection, type and press keys first. It is how the pictures here are made and how a change to the grid is checked from a script.

How it works

The sheet is sparse: cells live in a hash table keyed by a packed row and column, and an empty cell costs nothing. Formulas are parsed once and kept as trees. Each formula cell records the rectangles it reads; when a cell changes the sheet marks stale every formula whose rectangles contain it, and theirs in turn, and nothing is recomputed until something asks. The evaluator does not know what a sheet is: it reads values through a callback, which is why the engine builds as a library of its own and is driven from a terminal. Cell formats are interned, as word42's character formats are. docs/ARCHITECTURE.md goes into detail.

src/util/      cell addresses, values, number formats, dates
src/model/     the sheet, the book, charts, shapes, undo
src/formula/   the parser, the evaluator, the function library
src/io/        .gnumeric, .xlsx, .xls, .ods, CSV and the rest, PDF, SQLite
src/script/    Python: the office42 module, the interpreter
src/ui/        the grid, the window, the dialogs
src/main.c        the window's entry point
src/calc-main.c   the terminal front-end
data/          menus, icons, stylesheet
docs/          the guide, the architecture, the parity review

The model and the formula engine never include GTK.

Prior art

office42 studies three projects and copies none of their code: Gnumeric for what a spreadsheet engine should get right; AbiWord, by way of word42, for interned formatting and symmetric undo records; and northstar-browser for how to ship a large C/GTK 4 program with Meson and CI on three platforms.

Licence

GPL-3.0-or-later. See LICENSE.

office42 is an independent program. It is not affiliated with, endorsed by or derived from Microsoft, the GNOME Foundation or The Document Foundation, and no code, artwork or resource of theirs is in it. Microsoft, Excel and Office Open XML are trademarks of Microsoft Corporation; Gnumeric and GTK belong to the GNOME Foundation; the other names used here belong to their owners, and are used only to say what office42 reads, writes or resembles. NOTICE.md lists them and gives the terms of every library office42 links against.