coordinate-systems
Testing & QualityUse when working with row or column indexes in Handsontable - translating between physical, visual, and renderable coordinates, using IndexMapper, or debugging index-related bugs where rows or columns appear in wrong positions
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Coordinate Systems
Handsontable uses three coordinate systems because the position of a row or column can differ depending on whether you are looking at the raw data, the logical grid after filtering/trimming, or the actual DOM. Mixing them up is one of the most common sources of bugs.
The three systems
| System | What it represents | Key behavior |
|---|---|---|
| Physical | Position in the source data array (0 to N) | Never changes regardless of filtering, sorting, trimming, hiding, or moving. Always 0 to N. |
| Visual | Position in what Handsontable has processed | Changes when data is filtered, sorted, trimmed, or columns/rows are moved. Hidden columns/rows still have visual indexes - hiding does not remove from visual space. |
| Renderable | Position in the DOM | Only matters for Walkontable. Very rarely used in public API and Handsontable. |
The public Handsontable API mainly uses visual indexes, sometimes physical, and very rarely renderable (if any).
In Walkontable (the rendering engine), the data is already filtered, sorted, trimmed (etc.) by Handsontable, so Walkontable renders it as-is from 0 to N. Walkontable also uses "source index" and "render index" internally for virtualization - calculating what needs to be rendered at the current scroll position.
HidingMap vs TrimmingMap
- HidingMap - The index stays in the DataMap (visual space) but is not rendered in the DOM. Used by
HiddenColumnsandHiddenRows. Important: hidden columns/rows still have visual indexes. The data is still accessible viagetDataAtCell()with visual coordinates. - TrimmingMap - The index is removed from the DataMap entirely. Used by
TrimRowsandFilters. Trimmed rows do not exist in visual space at all.
IndexMapper API
Access via hot.rowIndexMapper or hot.columnIndexMapper. Key methods:
// Translate between systems
mapper.getPhysicalFromVisualIndex(visualIndex)
mapper.getVisualFromPhysicalIndex(physicalIndex)
mapper.getPhysicalFromRenderableIndex(renderableIndex)
mapper.getRenderableFromVisualIndex(visualIndex)
// Register a new map
mapper.createAndRegisterIndexMap(name, type, initialValue)
// type: 'hiding' | 'trimming'
When to use which coordinate
| You are doing | Use |
|---|---|
| Reading or writing source data | Physical |
Working with user-facing row/column positions, selection, or getDataAtCol() | Visual |
| Accessing DOM nodes, cell elements, or Walkontable APIs | Renderable |
| Storing persistent state (e.g., sorting order, filter conditions) | Physical |
Common gotcha: Filters + ManualColumnMove
The conditionCollection and conditionUpdateObserver in the Filters plugin operate on physical indexes, while getDataAtCol() requires visual indexes. When manualColumnMove is active, physical and visual column order diverge. Always convert with getVisualFromPhysicalIndex() / getPhysicalFromVisualIndex() before crossing the boundary.
Quick plugin reference
| Plugin | Map type | Coordinate it manages |
|---|---|---|
HiddenColumns / HiddenRows | HidingMap | Visual to renderable |
TrimRows / Filters | TrimmingMap | Physical to visual |
ManualColumnMove / ColumnSorting | IndexesSequence | Physical to visual |
Source files
Implementation lives in src/translations/ - see indexMapper.ts, maps/, and mapCollections/. For the deep subsystem reference (map types, translation methods, cache, observers, registration lifecycle), see handsontable/.ai/INDEX-MAPPING.md; for wider system context, handsontable/.ai/ARCHITECTURE.md.