2. The look of the bar

The bar of chapter 1 is a row of stars. Its look is made of elements, each one a string you choose:

call bar%initialize(prefix_string='march ', suffix_string=' time steps', &
                    bracket_left_string='[', bracket_right_string=']',   &
                    filled_char_string='#', empty_char_string='.',       &
                    width=40, max_value=real(steps, R8P))

While running:

$ march
march [####################....................] time steps

The line is drawn in this order:

prefix  bracket_left  filled × n  empty × (width − n)  bracket_right  suffix
march   [             ##########  ..........           ]              time steps

• width is the number of characters between the brackets; n is the progress times width, rounded.
• filled_char_string and empty_char_string are repeated n and width − n times: use one character each, or the bar becomes wider than width.
• The prefix, the brackets and the suffix are drawn as given, spaces included: prefix_string='march ' ends with a space to keep the name apart from the bracket.

Unicode

Every string can be Unicode: write it in the source, saved as UTF-8.

call bar%initialize(prefix_string='march ', bracket_left_string='▕', bracket_right_string='▏', &
                    filled_char_string='█', empty_char_string='░',                         &
                    width=40, max_value=real(steps, R8P))

$ march
march ▕████████████████████░░░░░░░░░░░░░░░░░░░░▏

The strings are class(*): plain literals as above, or literals of the UCS4 kind that forbear exports (UCS4_'█'), both work.

A smooth bar

A character is a coarse step: with width=40, one step every 2.5%. partial_blocks=.true. draws the bar with the Unicode partial blocks ▏▎▍▌▋▊▉█, eight steps per character:

call bar%initialize(prefix_string='march ', bracket_left_string='▕', bracket_right_string='▏', &
                    partial_blocks=.true., filled_char_color_fg='cyan',                     &
                    width=40, max_value=real(steps, R8P))

$ march
march ▕██████████████████▍                     ▏

While running, at 46%: 18 full cells and three eighths of the next one. The done part is always the full block █, in the colours of filled_char; the empty part is empty_char_string, a space by default. To draw the track of the bar, give the empty part a background colour (empty_char_color_bg): the partial cell takes it too, and the bar has no seam.

What you learned

The elements of the line, their order, the width; Unicode strings; partial blocks. Reference: The bar object.

Next: 3. Colours and styles.