[iluebbe]

Fixes #1158 and #1159. Data bars told Excel's Automatic bounds and Lowest/Highest Value apart nowhere, and drew every bar from 0 with a fixed 10 % head start.

Builds on #717 (Excel 2010 conditional formats, @neilcawse). That PR moves the x14 data bar reader and writer this one extends, so this branch starts from its head (6f0f747) and contains its four commits until it merges. Please merge #717 first; I'll rebase this one onto main then.

Problem

• Bounds (Conditional formatting: data bar bounds Automatic and Lowest/Highest Value are read and written as one #1159). Excel writes both Automatic and Lowest/Highest Value as <cfvo type="min"/> / max in the main section; only the x14 rule tells them apart (autoMin/autoMax). GridCraft read both as Min/Max and evaluated Min as Automatic. It wrote its own bars without x14 bounds, which Excel reads as Lowest/Highest Value. So a bar made in GridCraft looked different in Excel, and an Excel bar with Lowest Value looked different in GridCraft.
• Lengths (Conditional formatting: data bars with a fixed minimum (number, percent, percentile, formula, lowest value) are drawn from 0 #1158). CfCache::look pulled every positive minimum to 0 and drew frac × 0.9 + 0.1. A bar with a fixed minimum (Number, Percent, Percentile, Formula, Lowest Value) was too long, and a value at the minimum got half a bar instead of none. The bar lengths in the file (minLength/maxLength) were ignored.

Fix

• Model (features.rs):
  • CfValueKind::AutoMin and AutoMax, documented as data-bar only.
  • CfRule::DataBar gets min_length and max_length (percent of the cell). The serde defaults are 10 and 90, a file's defaults.
• Evaluation (cf.rs):
  • Automatic minimum: 0, or the lowest value when that is negative, as before. Every other minimum is used as it is.
  • The bar is minLength + frac × (maxLength − minLength) of the cell, with frac = (value − min) / (max − min) clamped to 0…1.
• XLSX read (sheet_read.rs):
  • autoMin/autoMax become AutoMin/AutoMax.
  • The x14 rule a main-section bar links to now gives its bounds and lengths as well as its fill. The main section's minLength/maxLength are read too.
  • Only borders, the axis and negative bar colours still give the "partly skipped" warning.
• XLSX write (sheet_write.rs):
  • Automatic is written as min/max in the main section and autoMin/autoMax in the x14 rule, as Excel does.
  • A bar gets its x14 rule when it needs one: solid fill, an Automatic bound, or lengths other than 10–90. Lengths go in both sections.
  • XLSX: read, evaluate and write Excel 2010 conditional formats #717's solid_bar_* helpers become bar_x14_*.
• Command: home.conditionalFormat data bars default to Automatic and 0–100 %, as Excel's Data Bars gallery makes them. min/max also take autoMin/autoMax. The ribbon gallery and the sample workbooks get Automatic bars.

Measured in Excel for Microsoft 365

A file written by this branch, opened in its own Excel instance. Bounds, fill and lengths come from COM (Databar.MinPoint.Type, BarFillType, PercentMin/PercentMax). Bar length is a fraction of the full bar, from a capture of Excel's window (solid bars).

Rule (GridCraft command)	Excel reads	Excel draws
{"type": "dataBar"} over 10…20	Automatic Min/Max (6/7), 0–100	10 → 0.50, 15 → 0.76, 20 → 1.0
min/max over 10…20	Lowest/Highest Value (1/2), 0–100	10 → 0, 11 → 0.09, 15 → 0.51, 20 → 1.0
Number 3 – Number 8 over 0…10	Number (0/0), 0–100	3 → 0, 4 → 0.21, 6 → 0.60, 8 → 1.0
Gradient, min/max, 10–90 (no x14 rule)	Lowest/Highest Value, gradient, 10–90	(2007 bar, as before)

These are the values data_bar_lengths_as_in_excel expects, with #1158's table for Percent, Percentile and Formula.

Bar lengths and the axis. The lengths behave as above only without an axis. Measured over 0…10, Lowest to Highest, solid:

minLength–maxLength	No axis (axisPosition="none")	Automatic axis (the default)
0–50	not measured	0 → 0, 10 → 0.51
50–100	0 → 0.51, 10 → 1.0	0 → 0.26, 10 → 0.76
20–100	0 → 0.21, 10 → 1.0	0 → 0.09, 10 → 0.91
40–60	0 → 0.40, 10 → 0.60	0 → 0.21, 10 → 0.40

With Excel's automatic axis, a nonzero shortest bar is halved: minLength/2 + frac × (maxLength − minLength). A bar without an x14 rule (Excel 2007, other writers; 10–90) is drawn like the no-axis column.

GridCraft draws no axis, which is #781's work, so it draws every bar like the no-axis column. That matches Excel for:

• every bar Excel's dialogs can make, since they are always 0–100;
• every bar this command makes;
• bars without an x14 rule.

Only a bar with a nonzero minLength from VBA or another writer, on Excel's automatic axis, still differs. For that reason home.conditionalFormat takes no length parameters.

Testing

• data_bar_lengths_as_in_excel (engine): the command's default bar and Number, Percent, Percentile, Formula and Lowest/Highest bounds, against the measured values (tolerance 0.02).

• data_bar_lengths_from_a_file (engine): lengths 10–90, 50–100, 20–100 and 40–60, against the no-axis measurements.

• data_bar_bounds_and_lengths (xlsx), from Excel-shaped XML:

  • an Automatic gallery bar with border, axis and negative colours (→ AutoMin/AutoMax, 0–100, one "partly skipped" warning);
  • a solid Lowest/Highest bar;
  • a bar without an x14 rule (→ 10–90);
  • a main-section bar with lengths 20–80.

  Writing it back gives three x14 rules with the expected bounds and lengths, no autoMin in the main section, and the same rules on reading, without warnings.

• XLSX: read, evaluate and write Excel 2010 conditional formats #717's x14_conditional_formats_are_read: its x14 bar (Automatic, 0–100, solid) now reads with those bounds and lengths. It no longer warns, since the model holds all of its settings.

• full_roundtrip: its data bar carries lengths 5–95.

• cargo xtask ci: fmt, clippy, test, assets, layers and wasm pass.

  • parity and keytips report their generated files out of date on this Windows checkout (core.autocrlf).
  • Regenerating them changes only line endings: git diff is empty, as on main.
  • After rebasing onto XLSX: read, evaluate and write Excel 2010 conditional formats #717's latest commit, gridcraft-xlsx (176 tests) and the engine's cf:: tests pass again.

Conflicts:

• Conditional formatting: icon thresholds with ">" (gte="0") #1199 also edits the home.conditionalFormat parameter line and the icon-set arm next to the data bar arm in insert.rs.
• x14 conditional-format extensions: import, render, round-trip (data-bar fill/border/negative/axis/limits, custom + 2010 icon sets) #781 adds data bar fields of its own.

The merges are mechanical.

🤖 Generated with Claude Code

https://claude.ai/code/session_01SAgnkqJiy3v24Hp25dQLRj

[iluebbe]

Closing this pull request. #1158 and #1159 describe the problem; their new comments add the bar-length measurements (with and without Excel's axis) and the fix approach. A fix fits on top of #717.