A custom mark type that turns one measure + one date into an interactive metric card, bound to the Marks card (so it travels with the worksheet).
Shared viz-extension techniques (reading encodings, live updates, responsive/no-scroll degradation, etc.) are not repeated here, they live globally in
reference/viz-extensions.md. This file covers only what's specific to the KPI Card.
#What it is
- Current value (latest period) + ▲/▼ period-over-period delta pill.
- Chart type: line, area, or bars, or hide the chart entirely. With the chart hidden the card centers as a big-number tile.
- Comparisons, stackable: MoM (the delta pill), YoY (vs. a point ~1 year back, when the data spans that far), vs Goal (vs. 1.15× the active range's average).
- Overlays: a dashed goal line on the chart, min/max/avg/total, the trend pill (rising/falling/flat), and bar value labels (bars chart type, wide-enough bars only).
- Fills: solid accent, a two-color gradient (accent → second color), or, with a second measure bound to Color and the bars chart type, the bars ramped by that second measure (bar length = measure 1, bar color = measure 2, e.g. length = Sales, color = Profit).
- Number format: currency, plain number, or percent, applied everywhere a value shows (the headline, stats, tooltips).
- Play / replay / compare buttons (top right; Configure can hide them): play draws the chart in while the headline counts up; compare overlays the previous period (the window before a brush, or the latest half vs the half before) with both totals in a legend.
- Scrub the sparkline to retarget the value + delta to a period; brush a date window to recompute over just that range; click / double-click resets.
- Scales to fill any pane and sheds detail near the limits down to number-only (see the global responsive pattern).
- Configure (the ⚙ gear, top-right) also live-previews every change on the card as you make it, Save still persists to the workbook, same as any extension.
#Encodings (Marks card)
| Tile | Required | Accepts |
|---|---|---|
| Measure | yes | one continuous measure (e.g. SUM(Sales)), this is the bar length / line value |
| Date | yes | one date, use a continuous date (e.g. MONTH(Order Date)) |
| Color | no | an optional second measure (e.g. SUM(Profit)), ramps the bar fill when "color bars by the 2nd measure" is on |
#Run it locally
From the repo root: python scripts/kitserve.py (serves every extension on 8765).
It answers on both IPv4 and IPv6 and resolves lib/ to _shared/lib; a plain
python -m http.server does neither, which is what makes a local extension load
as a blank or errored zone.
In Tableau, on a worksheet’s Marks card → mark-type dropdown → Add Extension… → Access Local Extensions →
manifest.local.trex. Drag a measure onto Measure and a continuous date onto Date.