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.. SPDX-License-Identifier: BSD-2-Clause
Copyright 2013-2023, John McNamara, jmcnamara@cpan.org
.. _ex_inheritance2:
Example: Advanced example of subclassing
========================================
Example of how to subclass the Workbook and Worksheet objects. See also the
simpler :ref:`inheritance1.py <ex_inheritance1>` example.
In this example we see an approach to implementing a simulated autofit in a
user application. This works by overriding the ``write_string()`` method to
track the maximum width string in each column and then set the column widths
when closing the workbook.
Some notes on this:
* **This isn't a fully functional autofit example** (as shown by the longer
strings in the screen shot). It is only a proof or concept or a framework to
try out solutions. See the the worksheet :func:`autofit` method instead.
* The hard part is coming up with an accurate (or mainly accurate)
``excel_string_width()`` function. One possibility is to use the PIL
`ImageFont()
<https://pillow.readthedocs.io/en/latest/reference/ImageFont.html>`_ method
and convert the pixel width back to a character width.
* A more rigorous approach would have to consider font sizes, bold, italic,
etc.
* The ``set_column()`` calls in ``close()`` will override any others set by the
user. They also don't set any column formats.
* It doesn't work for horizontal merge ranges.
* There are probably some other corner cases hiding here.
.. image:: _images/inheritance2.png
.. literalinclude:: ../../../examples/inheritance2.py
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