<< Back to man.ChinaUnix.net

5.4. Packing Using Tables

Let's take a look at another way of packing - Tables. These can be extremely useful in certain situations.

Using tables, we create a grid that we can place widgets in. The widgets may take up as many spaces as we specify.

The first thing to look at, of course, is the gtk_table_new() function:

GtkWidget *gtk_table_new( guint    rows,
                          guint    columns,
                          gboolean homogeneous );

The first argument is the number of rows to make in the table, while the second, obviously, is the number of columns.

The homogeneous argument has to do with how the table's boxes are sized. If homogeneous is TRUE, the table boxes are resized to the size of the largest widget in the table. If homogeneous is FALSE, the size of a table boxes is dictated by the tallest widget in its same row, and the widest widget in its column.

The rows and columns are laid out from 0 to n, where n was the number specified in the call to gtk_table_new. So, if you specify rows = 2 and columns = 2, the layout would look something like this:

 0          1          2
0+----------+----------+
 |          |          |
1+----------+----------+
 |          |          |
2+----------+----------+

Note that the coordinate system starts in the upper left hand corner. To place a widget into a box, use the following function:

void gtk_table_attach( GtkTable         *table,
                       GtkWidget        *child,
                       guint            left_attach,
                       guint            right_attach,
                       guint            top_attach,
                       guint            bottom_attach,
                       GtkAttachOptions xoptions,
                       GtkAttachOptions yoptions,
                       guint            xpadding,
                       guint            ypadding );

The first argument ("table") is the table you've created and the second ("child") the widget you wish to place in the table.

The left and right attach arguments specify where to place the widget, and how many boxes to use. If you want a button in the lower right table entry of our 2x2 table, and want it to fill that entry only, left_attach would be = 1, right_attach = 2, top_attach = 1, bottom_attach = 2.

Now, if you wanted a widget to take up the whole top row of our 2x2 table, you'd use left_attach = 0, right_attach = 2, top_attach = 0, bottom_attach = 1.

The xoptions and yoptions are used to specify packing options and may be bitwise OR'ed together to allow multiple options.

These options are:

GTK_FILL

If the table box is larger than the widget, and GTK_FILL is specified, the widget will expand to use all the room available.

GTK_SHRINK

If the table widget was allocated less space then was requested (usually by the user resizing the window), then the widgets would normally just be pushed off the bottom of the window and disappear. If GTK_SHRINK is specified, the widgets will shrink with the table.

GTK_EXPAND

This will cause the table to expand to use up any remaining space in the window.

Padding is just like in boxes, creating a clear area around the widget specified in pixels.

gtk_table_attach() has a lot of options. So, there's a shortcut:

void gtk_table_attach_defaults( GtkTable  *table,
                                GtkWidget *widget,
                                guint      left_attach,
                                guint      right_attach,
                                guint      top_attach,
                                guint      bottom_attach );

The X and Y options default to GTK_FILL | GTK_EXPAND, and X and Y padding are set to 0. The rest of the arguments are identical to the previous function.

We also have gtk_table_set_row_spacing() and gtk_table_set_col_spacing(). These places spacing between the rows at the specified row or column.

void gtk_table_set_row_spacing( GtkTable *table,
                                guint     row,
                                guint     spacing );

and

void gtk_table_set_col_spacing ( GtkTable *table,
                                 guint     column,
                                 guint     spacing );

Note that for columns, the space goes to the right of the column, and for rows, the space goes below the row.

You can also set a consistent spacing of all rows and/or columns with:

void gtk_table_set_row_spacings( GtkTable *table,
                                 guint    spacing );

And,

void gtk_table_set_col_spacings( GtkTable *table,
                                 guint     spacing );

Note that with these calls, the last row and last column do not get any spacing.