Adjustable tables
Tables' default width gets computed based on the width of the tables' items. An optional table setting enables adjustable tables. Adjustable tables allow their width to expand, and their individual columns' relative width to be manually adjusted using the mouse pointer.
table2.C is a modified version of the example from this chapter that enables adjustable table features:
ntlm.adjustable("main_table"); ntlm.table_width=200; ntlm.maximum_table_width=500;
x::w::new_tablelayoutmanager's
adjustable() enables adjustable table columns
and assigns the table's label for
saving the adjustable
table column widths and restoring them the next time the
table window gets opened.
Moving the mouse pointer on top of a dividing border
in the header row changes the pointer to
a bi-directional horizontal arrow. Pressing pointer button #1 drags
the border under the pointer horizontally and adjusts the relative
widths of the columns on both sides of the border.
Pressing pointer button #1 while holding down the
Alt key restores all columns to their initial
unadjusted width.
Setting table_width and
maximum_table_width specifies the initial and the
maximum width of the table, in millimeters.
table2.C's window's width is expandable, this
adjusts the size of its table until its table reaches its maximum
width.
Calling unlimited_table_width() removes the
maximum limit for the table's width, completely.
Note
Other widgets in the same window affect the table's actual and maximum widths. The main window's grid layout manager (or the table's container's layout manager) has to calculate the other window elements' metrics. Unless the other widgets in the window can be sized accordingly, the table may not end up being sizable to its maximum width.
Adjusting table column widths using the keyboard
Each border between the columns in an adjustable table is draggable directly, by the pointer. This adjusts the relative sizes of the two columns on either sides of the border. The column sizes are also adjustable using the keyboard.
When the keyboard focus is on the table's list the Tab key highlights each border in the header row in turn the Tab key moves the keyboard focus out of the talbe list, as with other focusable widgets (Shift-Tab highlights the previous border in this mode). Cursor-Left and Cursor-Right move the highlighted border by a moderate amount, and by one precise pixel together with the Ctrl key.
Column width adjusting mode gets terminated immediately by the Esc key, or by repeatedly tabbing until the keyboard focus leaves the table list, or the header row. Pressing Esc while holding down the Alt key goes one step further and restores all columns to their initial unadjusted width.
Preserving table columns' widths
It's natural to expect that reopening an application opens the
table and its columns using their original size. This behavior
is enabled by assigning a unique label to each table in the window,
and passing this label to adjustable().
table2.C gives an example of
enabling adjustable table columns:
x::w::new_tablelayoutmanager ntlm{ // ... }; ntlm.adjustable("main_table"); f->create_focusable_container ([&] (const x::w::focusable_container &) { // ... }, ntlm);
A unique identifier must get assigned to each table in a window that
has adjustable columns.
table2.C calls its sole table, unimaginatively,
“main_table”.
ntlm.adjustable();
Calling adjustable() without any parameters
enables adjustable table column widths, but they do not get preserved
and each time the window gets opened the column widths get reset
to their default values.
ntlm.adjustable("main_table", false);
Passing a false as the optional 2nd parameter
enables adjustable column widths, but resets all column widths to their
default values. They'll still get preserved and the next time the
window gets opened the column widths will get restored to what they
were, once more.