TIP #37 Version 1.1: Uniform Rows and Columns in Grid

This is not necessarily the current version of this TIP.

Abstract

This TIP proposes to add a -uniform option to grid rowconfigure and grid columnconfigure so as to make it easier to create layouts where cells are constrained to have identical dimensions.

Introduction

The geometry managers in Tk are very powerful and can do most things needed to layout a GUI. One thing that is tricky to do though is to put widgets in rows or columns of the same width. This would be useful for example to layout a row of buttons symmetrically. This could easily be done with the grid manager if an additional option is added.

Specification

Anywhere column is used below, the same applies to row too.

A new option, -uniform, is added to grid columnconfigure. The option takes an arbitrary string, the default value being the empty string. Any column with a non-empty value will be grouped with other columns with the same value. All columns in a group will get the size of the group's smallest member.

In the grid algorithm, -uniform will be used before -weight. Thus the requested size will be affected by -uniform, but the distribution of extra size will only take -weight into consideration.

A consequence is that the columns in a -uniform group should have the same -weight to ensure that they have the same width after a resize.

Rationale

To put -uniform before -weight in the algorithm was based mainly on simplicity. It gives a simpler algorithm that is both easier to explain to the user and to code.

The alternative would be to force the -weight value to be same for all columns in a group before doing the resize calculations. The only benefit for the user would be to only have to specify -weight for one column in a group, but in practice this is hardly no gain at all since a typical usage looks like this:

grid columnconfigure . {0 1 2} -uniform a -weight 1

Implementation

A quick try shows that this is fairly straightforward to implement. The memory cost for the change is a Tk_Uid field in the column slot structure to hold the option, and the CPU overhead is small for a grid that don't use the option.

Copyright

This document has been placed in the public domain.

This is not necessarily the current version of this TIP.