1.  Tabular

Tabular is a Tcl/Tk mega-widget for handling tables of data. It can efficiently manage large data variables, has a treeview mode for hierarchical data, and supports multiple images/windows/text/tags per cell. Tabular also comes with the mini-database applet EdiTbl.tcl to exercise some of its capabilities. (download here)

2.  Features

• Auto-sizing columns for visible cell.
• Interactively resizable columns.
• Sort columns with click on title.
• Column alignment: left, right, center and numeric.
• Columns defined by tab chars providing fast dynamic resizing.
• Support for -variable (array or list) as well as callback commands (eg. sqlite)
• Cell's with any number of text/tags, images and/or windows.
• A tree mode for displaying hierarchical data.
• Good performance with large data sets (eg. 100K+ rows).
• Implementation is pure Tcl ($tk_version >= 8.3).

3.  Programming

Programming information is available in the interface specification and auto-documentation, viewing the tests code, or by inspecting the widget code directly.

Tabular uses two Tk text widgets: one for the title row and the other for the body or remaining rows in table. Direct access to sub-widgets is used to manage tags, text, images, etc, while minimizing the size of the Tabular API.

4.  Cells

A row of cells is simply a line of text where each cell begins with a pair of tabs "\t\t" and ends with a single tab "\t". Consequently, cell data containing the characters "\t", "\r" or "\n" is escaped with a backslash.

Cells in Tabular are indexed using COL,ROW order, ie. as in spreadsheet. Cell numbering starts from 0, and row 0 contains the column titles (but there are no row titles).

Tabular can handle large data reasonably well because it implements dynamic tagging and/or filling-in of rows as they appear. Tagging consists of adding the following tags to cells/rows:

   #cell #oddrow #oddcol #oddcell #rowNNN #colNNN

5.  Variables

The -variable option is intended to provide simple deferred loading of table data. Two types of variables are supported: array and list.

5.1  List

A list variable contains column titles in the first element, and data in the remaining rows.

5.2  Array

A array variable uses the empty element {} to contain titles. All other elements in the array are data rows, and these are displayed sorted by the key.

The special case where field names start with a dash - implies name/value pairs, with -fields containing the names. This is the same form used by tad, providing database-like features for arrays (eg. ad-hoc queries).

Simple examples of -variable are:

    package require Tabular
    # source Tabular.tcl

    variable ::x { {A B C} {1 2 3} {4 5 6} }
    pack [tabular .tx -variable ::x]

    variable ::y
    array set ::y { {} {A B C}  0 {1 2 3} 1 {4 5 6} }
    pack [tabular .ty -variable ::y]

One issue to be aware of with -variable is that user edits in Tabular automatically update the variable data. But changes to the variable do not appear as changes in the widget (unless the --syncvar option is also used).

6.  Tests

Various Tabular tests can be tried out using:

    wish Tabular.tcl -test

7.  Internal Requirements:

Requirements (except the optional Mod package) are actually included with the package.

1. solid.xpm (or write perms in appdir) for cell borders.
2. Either Modlite.tcl in appdir, or the package Mod.
3. Type checking and query, requires tad.tcl in appdir (if not using Mod).
4. Support for sqlite needs the tclsqlite package/library.
5. Combo (ie. with -type Choice) falls back to entry/spinbox without Mod.

8.  Issues

Column width calculations are not very accurate on really wide columns.

Tcl 8.4 is recommended for Tabular as there are several issues with $tk_version >= 8.5. The first is that Tk 8.5's text widget displays pathological scrollbar behaviour with large tables. Also, [clock scan] about 25 times slower, so if you must use 8.5+ consider using clockold.

© 2008 Peter MacDonald