Mastering Perl/Tk

The grid Geometry Manager

The grid geometry manager divides the window into a grid composed of columns and rows starting at (0, 0) in the upper-left corner. Figure 2-29 shows a sample grid.

Figure 2-29. A window divided into grids

Rather than using the sides of a window as reference points, grid divides the screen into columns and rows. It looks a lot like a spreadsheet, doesn’t it? Each widget is assigned a grid cell using the options available to grid.

The grid method takes a list of widgets instead of operating on only one widget at a time.^[1] Here is the generic usage:

$widget1->grid( [ $widget2, ... , ] [ option => value, ... ] );

A specific example is:

$widget1->grid($widget2, $widget3);

Instead of using three separate calls, you can use one grid call to display all three widgets. You can also invoke grid on each widget independently, just as you can pack. Each call to grid will create another row in the window. So in our example, $widget1, $widget2, and$widget3 will be placed in the first row. Another call to grid creates a second row. This is what happens when you do not specify any additional options to the grid call.

The previous example can be rewritten like this:

Tk::grid($widget1, $widget2, $widget3);

But beware, this is not necessarily equivalent to the previous statement, due to inheritance, an object-oriented concept. For more information, please refer to Chapter 14 ...