`ProgressBar` can be caused to crash with CSS since 5.0.0

[davep]

Given this code:

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

class WideBarApp(App[None]):

    CSS = """
    ProgressBar Bar {
        width: 1fr;
    }
    """

    def compose(self) -> ComposeResult:
        yield ProgressBar()

if __name__ == "__main__":
    WideBarApp().run()

Up until Textual 4.x, it ran fine. As of Textual 5.0 it causes the following crash (trimmed to the last bit, because the traceback ends up being way too big for a GitHub issue; to the point that it refuses to accept it):

│ /Users/davep/temp/wide-bar/.venv/lib/python3.11/site-packages/textual/widgets/_progress_bar.py:100 in render        │
│                                                                                                                     │
│    97 │   def render(self) -> RenderResult:                                                                         │
│    98 │   │   """Render the bar with the correct portion filled."""                                                 │
│    99 │   │   if self.percentage is None:                                                                           │
│ ❱ 100 │   │   │   return self.render_indeterminate()                                                                │
│   101 │   │   else:                                                                                                 │
│   102 │   │   │   bar_style = (                                                                                     │
│   103 │   │   │   │   self.get_component_rich_style("bar--bar")                                                     │
│                                                                                                                     │
│ ╭─────── locals ───────╮                                                                                            │
│ │ self = Bar(id='bar') │                                                                                            │
│ ╰──────────────────────╯                                                                                            │
│                                                                                                                     │
│ /Users/davep/temp/wide-bar/.venv/lib/python3.11/site-packages/textual/widgets/_progress_bar.py:128 in               │
│ render_indeterminate                                                                                                │
│                                                                                                                     │
│   125 │   │   else:                                                                                                 │
│   126 │   │   │   speed = 30  # Cells per second.                                                                   │
│   127 │   │   │   # Compute the position of the bar.                                                                │
│ ❱ 128 │   │   │   start = (speed * self._clock.time) % (2 * total_imaginary_width)                                  │
│   129 │   │   │   if start > total_imaginary_width:                                                                 │
│   130 │   │   │   │   # If the bar is to the right of its width, wrap it back from right to le                      │
│   131 │   │   │   │   start = 2 * total_imaginary_width - start  # = (tiw - (start - tiw))                          │
│                                                                                                                     │
│ ╭─────────────── locals ────────────────╮                                                                           │
│ │ highlighted_bar_width = 0.0           │                                                                           │
│ │                  self = Bar(id='bar') │                                                                           │
│ │                 speed = 30            │                                                                           │
│ │ total_imaginary_width = 0.0           │                                                                           │
│ │                 width = 0             │                                                                           │
│ ╰───────────────────────────────────────╯                                                                           │
╰─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
ZeroDivisionError: float modulo

NOTE: 1 of 2 errors shown. Run with textual run --dev to see all errors.

[TomJGooding]

This seems a simple reprodution of the issue described in #6052?

[davep]

Looks the same, albeit a version that would be someone seeking¹ to expand the width of a ProgressBar rather than set it to 0. But, if it's seen as an acceptable crash from 5.0 onwards, so be it...

Footnotes

1. And failing to, of course, but what I was doing there isn't too odd and would be an intermediate step to the right approach and so will on occasion have someone report the issue. ↩

[github-actions]

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• Will McGugan