Charts

Native Excel chart (c:chartSpace) support: read, render, create, edit, and save charts, round-tripping through .xlsx. The chart definition's source of truth is the Excel-native OOXML model, so charts interoperate with Excel/WPS and need no proprietary migration.

Architecture

xl/charts/chartN.xml (c:chartSpace)          ← source of truth, in the .xlsx
  ├─ crates/workbook            parse + serialize + lossless round-trip
  ├─ crates/controller          ChartManager (in Status; undo/redo via snapshot)
  │    ├─ payloads              CreateChart / MoveChart / DeleteChart
  │    └─ get_charts()          → ChartInfo (live values re-read from source ranges)
  ├─ crates/wasms/server        GetCharts RPC + payload dispatch
  └─ packages/engine            ChartLayer in Spreadsheet.svelte, rendered with ECharts

• Source values are read live. get_charts resolves each series' reference (e.g. Sheet1!$B$2:$E$2) to current cell values, so editing data updates the chart. The OOXML numCache is only a fallback.
• Anchored by stable CellId. Charts shift with row/column insert/delete, like images.
• Rendering library: ECharts, bundled in logisheets-engine as an external dependency + tree-shaken (echarts/core + use()), rendered as a DOM overlay (.chart-layer) positioned from the grid.

What works

Capability	Status	Verified by
Read & display charts from .xlsx	✅	user + tests
Chart follows data edits (live values)	✅	chart_reflects_live_data
Select (click)	✅	user
Move (drag)	✅	move_chart_updates_anchor + user
Resize (corner handles)	✅	reuses MoveChart + user
Delete (Delete/Backspace)	✅	delete_chart_removes_it
Create from selection (toolbar 📊)	✅	create_chart_from_scratch + user
Save round-trips (incl. moved/created/deleted)	✅	tests
Lossless round-trip of chart part bytes	✅	chart_round_trips
Chart types: column, bar, line, area, pie, doughnut, scatter	✅	parser/serializer tests
Series colors match the workbook theme (scheme + RGB)	✅	chart_reflects_live_data
Reconfigure a chart's type/title (selection dropdown)	✅	update_chart_changes_type_and_title

Undo/redo works for all chart edits (snapshot-based).

Series fill colors are resolved from the OOXML: direct RGB passes through, and scheme colors (accent1..6, tx/bg/dk/lt, hyperlink) map to the workbook theme, so a loaded chart matches Excel's colors. A selected chart shows a type-picker dropdown (top-left) that reconfigures it in place via UpdateChart (keeping the anchor and data references); Engine.updateChart(id, {chartType, title}) is the programmatic entry point.

What's remaining

Fidelity gaps

• Category labels are not read live (values are); category axis uses the cached strCache labels.
• Color modifiers (lumMod/lumOff tints on scheme colors) and per-data-point pie slice colors are not applied — base scheme/RGB colors are.
• numCache is not written on save. Compliant readers recompute from the refs; a reader that only trusts the cache would show empty until recalculated.
• Style/color/font detail beyond type + title + legend position + axis titles is not modeled.

Coverage gaps

• Only column/bar/line/area/pie/doughnut/scatter. Combo, stock, radar, bubble, surface, 3-D, etc. are unsupported.
• Non-chart graphicData (SmartArt, OLE embeds) does NOT round-trip — the drawing graphicFrame model is chart-only, so such objects are dropped on save. (Plain charts and text-box shapes are preserved.)

Editing gaps

• Reconfiguring covers type and title; changing the legend position, axis titles, or the data range of an existing chart still needs UI.
• The insert button only creates a column chart; no chart-type picker on insert (you can switch type after, via the selection dropdown).

Minor UX

• The mouse wheel does not scroll the grid while the cursor is over a chart (the transparent drag-capture cover swallows it); could re-dispatch wheel to the canvas like the React overlay layers do.

Key files

• crates/workbook/src/ooxml/chart.rs — parse (parse_chart) + generate (build_chart_xml).
• crates/workbook/src/ooxml/drawing_part.rs — graphicFrame anchor model.
• crates/controller/src/chart_manager/ — ChartManager + executor.
• crates/controller/src/api/worksheet.rs — get_charts (live-value resolution).
• packages/engine/src/lib/chart/ — ECharts setup + model + renderer.
• packages/engine/src/lib/components/Spreadsheet.svelte — ChartLayer, select/move/resize/delete, insertChart.
• src/components/toolbar/index.tsx — Insert Chart button.