Insert > Line or Area and the All Charts list offer 100% Stacked Area,
and insert.chart and chart.set take it as type area with subtype
stacked100. Each series' area stacks on the ones before it as its
share of the category's total. When every series on the value axis is
100% stacked and no value is negative, the axis runs from 0% to 100%.
A blank cell counts as zero, and a category whose total is zero stays
on the baseline.
An XLSX area chart with percentStacked grouping now opens as 100%
stacked and is saved back as percentStacked. It used to open as a
stacked area and was saved as stacked.
Checked black-box in Excel for Windows (Microsoft 365) with synthetic
workbooks: a bare name in <c:f> draws the whole chart blank, without a
repair prompt, for workbook- and sheet-scoped names alike, while
`[0]!Name` and `Sheet1!Name` plot.
- Write: a sheet-scoped name is written `Sheet!Name` (quoted when
needed) instead of bare; an already qualified name keeps its sheet;
an undefined name gets `[0]!`. A reference to an unknown sheet is
kept as written. A qualified series name is written as a strRef.
- Resolve: a series name `Sheet1!Name` is looked up on that sheet, as
the evaluator does, instead of being shown as literal text.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Excel writes a workbook-scoped defined name in a chart reference as
`[0]!Name`. The reader kept that text, the lexer took `[0]` for a
structured reference, and the series evaluated to #NAME?: a chart over
dynamic (OFFSET) names opened blank with one #NAME? category.
- Read: `[0]!Name` becomes `Name` in c:f (cat, val, xVal, yVal,
bubbleSize, tx), chartex cx:f and _xlchart names. External books
([1]Sheet1!...), quoted sheet names and strings are untouched.
- Write: a bare workbook-scoped name is written back as `[0]!Name`; a
sheet-scoped name stays bare. A series name that is a defined name is
written as a strRef instead of literal text.
- Resolve: a series name that is a defined name is evaluated.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A category range two or more columns wide beside a column of values (year beside month, Excel's
multiLvlStrRef) was read as one flat list: 36 rows in two columns became 72 categories, the
series sat in the left half of the plot and the years and months shared one row of labels.
Saving wrote the range as a plain strRef, so Excel lost the two-level axis too.
- gridcraft_core::category_levels: the shape of a category range beside its values (levels are
columns when the points run down the rows, rows when they run along the columns; up to three
outer levels), shared by the chart and xlsx crates.
- ChartData.category_levels: the outer levels, nearest the labels first, one entry per category,
non-empty where a group starts. resolve fills it; a single column is unchanged.
- render: the outer levels in rows under the labels, a group's name centred under its categories
with a separator at each boundary; in bar charts in columns beside the labels.
- xlsx: <c:cat> written as multiLvlStrRef with the level caches (innermost first), so the axis
survives a round trip.
Tests in core (shapes), chart (resolve and layout for columns, bars and a row of values) and
xlsx (written XML, read-back, stability, a single column stays strRef). chart-parity, gaps § 4
and the ROADMAP progress log updated.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Model: Series.trendlines (Vec<Trendline>, serde default) with kind
(linear, exponential, logarithmic, polynomial 2..6, power, moving
average 2..255), name, forward/backward forecast, set intercept,
equation / R² display and line colour, width and dash.
XLSX: read and write <c:trendline> in CT_Trendline child order, placed
after dLbls and before the data references in line, bar, area, scatter,
bubble and stock series; unknown types are skipped.
Chart: least-squares fits (transformed for exp/log/power, skipping
non-positive values; polynomials via normal equations on centred,
scaled x with partial pivoting), moving averages, forecasts that widen
the category or x axis, clipping to the plot, equation and R² labels and
legend entries ("Linear (Sales)"). Degenerate data draws nothing.
Engine: chart.addElement element="trendline" adds (type, series, order,
period, forward, backward, displayEquation, displayRSquared) or removes
trendlines; document.inspect lists each chart's trendlines.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A chart linked to a PivotTable: series are built from the report
(innermost row items x column items/value fields, totals excluded) and
rebuilt on every refresh or layout change; c:pivotSource round trip;
chart series accept union references.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A combo chart whose series have no kind of their own (as insert.chart
makes them) was written as one column group, and a stock chart as
clustered columns, so both reopened as clustered columns. Combo series
are now written as drawn (the first as columns, the others as lines),
and stock charts as a stockChart group (as lines when they don't have
the 3 or 4 series a stock chart needs).
Add support for Excel's "smoothed line" chart style. The smooth flag flows
model -> resolve -> chart render, persists through XLSX (<c:smooth val="1"/>),
and is toggled via the chart.addElement "smooth" element.
Rendering interpolates each gap-free run with a uniform Catmull-Rom spline
(0.5 tangent scale, 100 sub-segments per data segment), so the curve passes
through every data point and rounds the vertices — matching Excel's observed
behaviour. Long runs are still decimated before smoothing.
- model: Series.smooth (#[serde(default)], so old workbooks load unchanged)
- chart: SeriesData.smooth; smooth_run + catmull in render; wired through
resolve and the sanitize() copy; draw_runs takes the flag (line + scatter)
- engine: chart.addElement element="smooth"
- xlsx: read/write <c:smooth val> instead of hard-coding val="0"
- tests: smooth_line_adds_interpolated_points_and_keeps_endpoints,
smooth_line_splits_at_gaps, smooth_line_setting_round_trips
- examples/smooth_demo.rs: generates a straight+smooth side-by-side workbook
cargo xtask ci: all 7 steps pass.
dotCooCoo