condif2css

condif2css helps translate Excel conditional formatting into reusable CSS classes.

The library is designed to work with openpyxl workbooks and is currently focused on:

• Evaluating conditional-format formulas per cell (processor.process)
• Resolving workbook/theme/indexed colors to aRGB (create_themed_css_color_resolver)
• Building deduplicated CSS rules from Cell / DifferentialStyle objects (css.py)

What It Does

1. Reads conditional-format rules from an openpyxl worksheet.
2. Evaluates each rule formula against each target cell (with relative/absolute ref offsets).
3. Returns matching (sheet, cell, priority, dxf_id, stop_if_true) metadata.
4. Converts style objects into CSS declarations and stable class names.

Installation

Install from PyPI:

pip install condif2css

If the latest published version is a pre-release, use:

pip install --pre condif2css

Local development install:

pip install -e .

Or with uv (including dev dependencies):

uv sync --group dev

Quick Example

from openpyxl import load_workbook

from condif2css import (
    CssBuilder,
    CssRulesRegistry,
    argb_to_css,
    create_get_css_from_cell,
    create_themed_css_color_resolver,
    get_differential_style,
    get_theme_colors,
    process_conditional_formatting,
)

wb = load_workbook("input.xlsx", data_only=True)
ws = wb["Sheet1"]

theme_colors = get_theme_colors(wb)
get_argb = create_themed_css_color_resolver(theme_colors)

def get_css_color(color):
    argb = get_argb(color)
    return argb_to_css(argb) if isinstance(argb, str) else None

css_builder = CssBuilder(get_css_color)
css_registry = CssRulesRegistry(prefix="cf")
get_css_from_cell = create_get_css_from_cell(css_registry, css_builder)

# { "Sheet1\\!A1": ("Sheet1", "A1", priority, dxf_id, stop_if_true), ... }
matched_rules = process_conditional_formatting(ws)

# Apply each matched differential style and collect class names per cell
cell_classes = {}
for code, (_, _, _, dxf_id, _) in matched_rules.items():
    dxf = get_differential_style(wb, dxf_id)
    if dxf is None:
        continue
    cell_classes[code] = sorted(get_css_from_cell(dxf, is_important=True))

# Final CSS text
css_text = "\n".join(css_registry.get_rules())

Public API (Current)

• condif2css.create_themed_css_color_resolver(theme_colors)
• condif2css.get_theme_colors(workbook, strict=False)
• condif2css.process_conditional_formatting(sheet, fail_ok=True)
• condif2css.get_differential_style(workbook, dxf_id)
• condif2css.ThemeColorsError
• condif2css.CssBuilder
• condif2css.CssRulesRegistry
• condif2css.create_get_css_from_cell(...)
• condif2css.color.argb_to_css(...) and color/tint utility helpers

Current Scope and Limitations

• Conditional-format evaluation currently expects rules with exactly one formula.
• Formula evaluation expects references that resolve to single cells.
• Non-boolean formula results are ignored.
• Style extraction supports:
  • Borders: top/right/bottom/left
  • Alignment: horizontal/vertical
  • Fill: solid fills (or DifferentialStyle.fill.bgColor)
  • Font: size, color, bold, italic, underline
• The package provides building blocks; no CLI is included.

Development

Run tests:

pytest

Acknowledgements

• Theme color extraction is based on public-domain work by Mike-honey: https://gist.github.com/Mike-Honey/b36e651e9a7f1d2e1d60ce1c63b9b633

License

Licensed under either of:

• Apache License, Version 2.0 (LICENSE_APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE_MIT or https://opensource.org/licenses/MIT)

at your option.