`TextArea` wrapping tabs strangely with latest Rich

[TomJGooding]

When the text in the TextArea contains tabs, the wrapping seems a bit strange after upgrading to the latest Rich (14.3.0).

Here's a simple example with before and after screenshots for comparison:

rich 14.2.0	rich 14.3.0

from textual.app import App, ComposeResult
from textual.widgets import TextArea

TEXT = """\
#define SHORT_NAME\t\t 0x00FF
#define LONGER_NAME\t\t 0x0F0F
#define EVEN_LONGER_NAME 0xFFFF\
"""


class TextAreaExample(App):
    CSS = """
    TextArea { 
        width: 40;
    }
    """

    def compose(self) -> ComposeResult:
        yield TextArea(TEXT, show_line_numbers=True)


if __name__ == "__main__":
    app = TextAreaExample()
    app.run()

[github-actions]

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• How do I center a widget in a screen?

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[TomJGooding]

After a bit of digging, it looks like the problem is somewhere in compute_wrap_offsets:

from textual._wrap import compute_wrap_offsets
from textual.expand_tabs import get_tab_widths

line = "#define SHORT_NAME\t\t 0x00FF"

tab_sections = get_tab_widths(line, tab_size=4)
print(tab_sections)
# [('#define SHORT_NAME', 2), ('', 4), (' 0x00FF', 0)]

line_width = sum(len(section) + tab_width for section, tab_width in tab_sections)
print(line_width)
# 31

wrap_offsets = compute_wrap_offsets(
    line, width=32, tab_size=4, precomputed_tab_sections=tab_sections
)
print(wrap_offsets)
# rich 14.2.0: []
# rich 14.3.0: [21]

[TomJGooding]

I think I've found the problem. The width calculations expect cell_len from Rich to exclude tabs, but this isn't the case in the latest version.

textual/src/textual/_wrap.py

Lines 79 to 80 in 5013720

	for start, end, chunk in chunks(text):
	chunk_width = _cell_len(chunk) # this cell len excludes tabs completely

from rich.cells import cell_len

chunk = "SHORT_NAME\t\t "
chunk_width = cell_len(chunk)
print(chunk_width)
# rich 14.2.0: 11
# rich 14.3.0: 13

[TomJGooding]

Fixed in Rich 14.3.2 - thanks Will!

[github-actions]

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• Will McGugan