Measuring

Any string containing sequences can be measured by blessed using the length() method. This means that blessed can measure, right-align, center, truncate, or word-wrap its own output!

The height and width properties always provide a current readout of the size of the window:

>>> term.height, term.width
(34, 102)

By combining the measure of the printable width of strings containing sequences with the terminal width, the center(), ljust(), rjust(), truncate(), and wrap() methods “just work” for strings that contain sequences.

with term.location(y=term.height // 2):
    print(term.center(term.bold('press return to begin!')))
    term.inkey()

In the following example, wrap() word-wraps a short poem containing sequences:

from blessed import Terminal

term = Terminal()

poem = (term.bold_cyan('Plan difficult tasks'),
        term.cyan('through the simplest tasks'),
        term.bold_cyan('Achieve large tasks'),
        term.cyan('through the smallest tasks'))

for line in poem:
    print('\n'.join(term.wrap(line, width=25, subsequent_indent=' ' * 4)))

Resizing

To detect when the size of the window changes, you can author a callback for SIGWINCH signals:

import signal
from blessed import Terminal

term = Terminal()

def on_resize(sig, action):
    print(f'height={term.height}, width={term.width}')

signal.signal(signal.SIGWINCH, on_resize)

# wait for keypress
term.inkey()

Note

This is not compatible with Windows! We hope to make a cross-platform API for this in the future https://github.com/jquast/blessed/issues/131.

Sometimes it is necessary to make sense of sequences, and to distinguish them from plain text. The split_seqs() method can allow us to iterate over a terminal string by its characters or sequences:

>>> term.split_seqs(term.bold('bbq'))
['\x1b[1m', 'b', 'b', 'q', '\x1b(B', '\x1b[m']

Will display something like, ['\x1b[1m', 'b', 'b', 'q', '\x1b(B', '\x1b[m']

Method strip_seqs() can remove all sequences from a string:

>>> phrase = term.bold_black('coffee')
>>> phrase
'\x1b[1m\x1b[30mcoffee\x1b(B\x1b[m'
>>> term.strip_seqs(phrase)
'coffee'