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Measuring
=========
Any string containing sequences can be measured by blessed using the :meth:`~.Terminal.length`
method. This means that blessed can measure, right-align, center, truncate, or word-wrap its
own output!
The :attr:`~.Terminal.height` and :attr:`~.Terminal.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 :meth:`~.Terminal.center`, :meth:`~.Terminal.ljust`, :meth:`~.Terminal.rjust`,
:meth:`~Terminal.truncate`, and :meth:`~Terminal.wrap` methods "just work" for strings that
contain sequences.
.. code-block:: python
with term.location(y=term.height // 2):
print(term.center(term.bold('press return to begin!')))
term.inkey()
In the following example, :meth:`~Terminal.wrap` word-wraps a short poem containing sequences:
.. code-block:: python
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:
.. code-block:: python
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()
.. image:: https://dxtz6bzwq9sxx.cloudfront.net/demo_resize_window.gif
:alt: A visual animated example of the on_resize() function callback
.. 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 :meth:`~.Terminal.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 :meth:`~.Terminal.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'
.. _SIGWINCH: https://en.wikipedia.org/wiki/SIGWINCH
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